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1.  Effects of preinduced Candida-specific systemic cell-mediated immunity on experimental vaginal candidiasis. 
Infection and Immunity  1994;62(3):1032-1038.
It has been postulated that systemic cell-mediated immunity (CMI) is an important host defense factor against recurrent vaginal infections caused by Candida albicans. Using an estrogen-dependent murine model of vaginal candidiasis, we have previously shown that mice inoculated vaginally with C. albicans acquire a persistent vaginal infection and develop Candida-specific Th1-type systemic CMI. In the present study, experimental vaginitis was monitored in the presence of preinduced systemic Candida-specific CMI. Mice immunized systemically with C. albicans culture filtrate antigens (CaCF) in complete Freund's adjuvant (CFA) had Th1-type reactivity similar to that of vaginally infected mice. CaCF given to mice intravenously induced Candida-specific suppressor T (Ts) cells. Mice preimmunized with CaCF-CFA and given a vaginal inoculum of C. albicans had positive delayed-type hypersensitivity (DTH) reactivity from the time of vaginal inoculation through 4 weeks. Conversely, mice infected in the presence of Ts cells had significantly reduced DTH responses throughout the 4-week period in comparison with naive infected mice. However, the presence of Th1-type Candida-specific DTH cells or Ts cells, either induced in mice prior to vaginal inoculation or adoptively transferred at the time of inoculation, had no effect on the vaginal Candida burden through 4 weeks of infection. A similar lack of effects was obtained in animals with lower Candida population levels resulting from a reduction in or absence of exogenous estrogen. These results suggest that systemic Th1-type CMI demonstrable with CaCF is unrelated to protective events at the level of the vaginal mucosa.
PMCID: PMC186220  PMID: 8112837
2.  Candida-specific Th1-type responsiveness in mice with experimental vaginal candidiasis. 
Infection and Immunity  1993;61(10):4202-4207.
The role of systemic cell-mediated immunity (CMI) as a host defense mechanism in the vagina is poorly understood. Using a murine pseudoestrus model of experimental vaginal candidiasis, we previously found that animals given a vaginal inoculum of viable Candida albicans blastoconidia acquired a persistent vaginal infection and developed Candida-specific delayed-type hypersensitivity (DTH) responses. The present study was designed to characterize the peripheral CMI reactivity generated from the vaginal infection in mice and to determine whether pseudoestrus is a prerequisite for the induction of peripheral CMI reactivity. Mice treated or not treated with estrogen and given a vaginal inoculum of C. albicans blastoconidia were examined for 4 weeks for their vaginal Candida burden and peripheral CMI reactivity, including DTH responsiveness and in vitro Th1 (interleukin-2 [IL-2], gamma interferon [IFN-gamma]/Th2 (IL-4, IL-10)-type lymphokine production in response to Candida antigens. Results showed that although mice not treated with estrogen before being given a vaginal inoculum of C. albicans blastoconidia developed only a short-lived vaginal infection and harbored significantly fewer Candida CFU in the vagina compared with those given estrogen and then infected; DTH reactivity was equivalent in both groups. In vitro measurement of CMI reactivity further showed that lymph node cells from both estrogen- and non-estrogen-treated infected mice produced elevated levels of IL-2 and IFN-gamma in response to Candida antigens during the 4 weeks after vaginal inoculation. In contrast, lymph node cells from the same vaginally infected mice showed no IL-10 production and only small elevations of IL-4 during week 4 of infection. These results suggest that mice with experimental vaginal candidiasis develop predominantly Th1-type Candida-specific peripheral CMI reactivity and that similar patterns of Th1-type reactivity occur in mice regardless of the persistence of infection and the estrogen status of the infected mice.
PMCID: PMC281145  PMID: 8406809
3.  Mice immunized by primary vaginal Candida albicans infection develop acquired vaginal mucosal immunity. 
Infection and Immunity  1995;63(2):547-553.
It has been postulated that systemic cell-mediated immunity (CMI) is an important host defense mechanism against Candida infections of the vagina. However, in an estrogen-dependent murine model of experimental vaginal candidiasis, we recently showed that systemic Candida-specific Th1-type CMI induced by immunization with Candida culture filtrate antigen had no effect on vaginal Candida population levels during the course of a vaginal infection. In the present study, mice given a second vaginal inoculation in the presence of peripheral Candida-specific Th1-type CMI induced by prior vaginal infection had anamnestic-type increased delayed-type hypersensitivity (DTH) responses, concomitant with significantly fewer Candida organisms in the vagina than in primary-infected mice. In addition, organisms in secondary-infected mice were fragmented and superficial penetration into the epithelium was reduced. The systemic presence of Candida-specific T suppressor (Ts) cells that significantly suppressed the infection-derived anamnestic DTH reactivity did not abrogate the protective effect in the vagina. Additional experiments showed that vaginally immunized mice were not protected from gastrointestinal or systemic candidiasis and, in contrast to mice with a second vaginal infection, did not demonstrate anamnestic DTH reactivity. These results suggest that a moderate level of local protection against a Candida vaginal infection can be achieved by vaginal immunization but that the protective role of acquired peripheral Candida-specific Th1-type reactivity at the vaginal mucosa appears to be limited.
PMCID: PMC173030  PMID: 7822020
4.  Candida-Specific Antibodies during Experimental Vaginal Candidiasis in Mice  
Infection and Immunity  2002;70(10):5790-5799.
Protective host defense mechanisms against vaginal Candida albicans infections are poorly understood. Although cell-mediated immunity (CMI) is the predominant host defense mechanism against most mucosal Candida infections, the role of CMI against vaginal candidiasis is uncertain, both in humans and in an experimental mouse model. The role of humoral immunity is equally unclear. While clinical observations suggest a minimal role for antibodies against vaginal candidiasis, an experimental rat model has provided evidence for a protective role for Candida-specific immunoglobulin A (IgA) antibodies. Additionally, Candida vaccination-induced IgM and IgG3 antibodies are protective in a mouse model of vaginitis. In the present study, the role of infection-induced humoral immunity in protection against experimental vaginal candidiasis was evaluated through the quantification of Candida-specific IgA, IgG, and IgM antibodies in serum and vaginal lavage fluids of mice with primary and secondary (partially protected) infection. In naïve mice, total, but not Candida-specific, antibodies were detected in serum and lavage fluids, consistent with lack of yeast colonization in mice. In infected mice, Candida-specific IgA and IgG antibodies were induced in serum with anamnestic responses to secondary infection. In lavage fluid, while Candida-specific antibodies were detectable, concentrations were extremely low with no anamnestic responses in mice with secondary infection. The incorporation of alternative protocols—including infections in a different strain of mice, prolongation of primary infection prior to secondary challenge, use of different enzyme-linked immunosorbent assay capture antigens, and concentration of lavage fluid—did not enhance local Candida-specific antibody production or detection. Additionally, antibodies were not removed from lavage fluids by being bound to Candida during infection. Together, these data suggest that antibodies are not readily present in vaginal secretions of infected mice and thus have a limited natural protective role against infection.
PMCID: PMC128320  PMID: 12228309
5.  Circulating CD4 and CD8 T cells have little impact on host defense against experimental vaginal candidiasis. 
Infection and Immunity  1995;63(7):2403-2408.
The etiology of recurrent vulvovaginal candidiasis in otherwise healthy women of child-bearing age remains an enigma. To date, results from both clinical studies and a murine model of vaginal candidiasis indicate that Candida vaginitis can occur in the presence of Candida-specific Th1-type cell-mediated immunity expressed in the peripheral circulation. The present study was designed to determine the role of circulating CD4 and CD8 cells in primary and secondary vaginal infections with Candida albicans. Vaginal fungal burden, Candida-specific delayed-type hypersensitivity (DTH), and lymph node cell Th1/Th2 cytokine production were monitored in CD4 and/or CD8 cell-depleted mice during persistent primary vaginal infections and secondary vaginal infections against which partial protection was observed. Treatment of mice with anti-CD4 or anti-CD8 antibodies resulted in 90% or greater depletion of the respective cell populations. Mice depleted of CD4 cells had significantly reduced Candida-specific DTH and lymph node cell Th1-type cytokine production during a primary vaginal infection, as well as reduced anamnestic DTH during a secondary vaginal infection. In contrast, mice depleted of CD8 cells showed only reduced gamma interferon production during a primary infection; no alterations in DTH were observed. Despite reductions in DTH and cytokine production, however, CD4 and/or CD8 cell depletion had no effect on vaginal C. albicans burden in mice after a primary or secondary vaginal inoculation. Taken together, these results suggest that while circulating CD4 and CD8 cells contribute to systemic Candida-specific cell-mediated immunity in vaginally infected mice, neither CD4 nor CD8 circulating T cells appear to provide significant host defenses against C. albicans at the vaginal mucosa.
PMCID: PMC173321  PMID: 7790050
6.  Immunoregulation in experimental murine candidiasis: specific suppression induced by Candida albicans cell wall glycoprotein. 
Infection and Immunity  1985;49(1):172-181.
Immune regulation in candidiasis is inferred from studies of both human and animal infection, with a suppressive role suggested for cell wall polysaccharide. To study the immunosuppressive potential of Candida albicans in a murine model, whole blastoconidia or purified cell wall components of C. albicans were tested for their effects on the development of acquired immune responses by superimposing a pretreatment regimen upon an established immunization protocol. CBA/J or BALB/cByJ mice were pretreated twice intravenously with 100 micrograms of mannan (MAN), 100 or 200 micrograms of glycoprotein (GP), or 5 X 10(7) heat-killed C. albicans blastoconidia, followed 1 week later by an immunization protocol of two cutaneous inoculations of viable C. albicans blastoconidia given 2 weeks apart. Delayed hypersensitivity (DTH) to GP or to a membrane-derived antigen, B-HEX, was tested 7 days after the second inoculation, and lymphocyte stimulation was tested with mitogens and Candida antigens after 12 days. To assess protection, mice were challenged intravenously with viable C. albicans blastoconidia 14 days after the second cutaneous inoculation and sacrificed 28 days later for quantitative culture of kidneys and brains. Sera were obtained for enzyme-linked immunosorbent assays at selected intervals. Pretreatment with GP resulted in specific in vivo suppression of DTH to GP but not to B-HEX antigen and specific in vitro suppression of lymphocyte stimulation to GP but not to other Candida antigens or mitogens. MAN and heat-killed C. albicans blastoconidia had no such effects. GP pretreatment also diminished the protective effect of immunization against challenge, demonstrable in the brain, while not altering significantly the production of antibody in response to infection. Contrary to clinical evidence, MAN was not immunosuppressive in this model, and in fact, the immunosuppressive potential of GP, which is composed largely of MAN, was found to be dependent upon the presence of its heat-labile protein moiety.
PMCID: PMC262075  PMID: 4008047
7.  Induction of antigen-specific T suppressor cells by soluble Paracoccidioides brasiliensis antigen. 
Infection and Immunity  1988;56(4):734-743.
In naturally acquired paracoccidioidomycosis, patients have depressed in vivo and in vitro cell-mediated immune (CMI) responses to Paracoccidioides brasiliensis antigen. In addition, it has been reported that these patients have significant levels of circulating paracoccidioidal antigen in their sera. The primary purpose of this investigation was to assess the effects of P. brasiliensis antigen on the CMI responses in a mouse model. On the basis of findings with other fungal agents, we predicted that circulating paracoccidioidal antigen may be inducing suppressor cells which modulate the CMI response. In this study, we show (i) that a soluble P. brasiliensis culture filtrate antigen (Pb.Ag) emulsified in complete Freund adjuvant and injected subcutaneously into mice induces reasonably high levels of delayed-type hypersensitivity (DTH) in CBA/J mice; (ii) that Pb.Ag elicits DTH reactions specific for P. brasiliensis when injected into footpads of immunized mice; and (iii) that an intravenous injection of Pb.Ag induces a population of lymph node and spleen cells which, upon adoptive transfer, suppress the afferent limb of the DTH response to paracoccidioidal antigen. The afferent suppressor cells can be detected in spleens as early as 5 days after Pb.Ag treatment, are present in significant numbers by 7 days in both spleens and lymph nodes, and are virtually absent by 14 days. In contrast, at 14 days after antigen injection, efferent suppressor cells were detected in spleens and lymph nodes. The Pb.Ag-induced afferent suppressor cells specifically inhibit the antiparacoccidioidal DTH response. They are nylon wool-nonadherent cells, and their activity is abrogated by anti-Thy-1 and complement treatment, indicating that they are T lymphocytes. The phenotype of these afferent suppressor T cells is L3T4+ Lyt-1+2- I-J+. The Pb.Ag-specific suppressor cells described in this paper are similar to the Ts1 cells in the azobenzenearsonate, 4-hydroxy-3-nitrophenyl acetyl, and cryptococcal models of suppression of the DTH response and to the afferent suppressor cells in the dinitrofluorobenzene contact sensitivity system.
PMCID: PMC259363  PMID: 2964411
8.  Increased Levels of Candida albicans Mannan-Specific T-Cell-Derived Antigen Binding Molecules in Patients with Invasive Candidiasis 
Clinical and Vaccine Immunology  2006;13(4):467-474.
In addition to cytokines, CD4+ T cells have been found to secrete soluble, T-cell-derived antigen binding molecules (TABMs). These antigen-specific immunoproteins are thought to have immunoregulatory properties in the suppression of cell-mediated immunity (CMI) because they often associate with interleukin-10 (IL-10) and transforming growth factor beta. Decreased CMI causes susceptibility to infections caused by organisms which are normally nonpathogenic. In this situation, e.g., Candida albicans saprophytism may develop into invasive candidiasis. The difficult diagnosis of invasive candidiasis is based on the findings obtained from blood cultures and with tissue biopsy specimens, with some additional diagnostic value gained by the detection of Candida albicans mannan antigenemia and antimannan antibodies. In the present study, Candida albicans mannan-specific TABM (CAM-TABM) levels in the sera of patients with invasive candidiasis (n = 11), Candida colonization (n = 11) and noncolonization (n = 10), recurrent vulvovaginal candidiasis (n = 30), and atopic eczema dermatitis syndrome (n = 59) and healthy controls (n = 30) were analyzed. For 14 participants, the effect of mannan stimulation on TABM production and gamma interferon (IFN-γ) and IL-4 mRNA expression by peripheral blood lymphocytes was also studied. It was demonstrated that CAM-TABM production was the highest in patients with invasive candidiasis and that CAM-TABM levels could distinguish Candida-colonized patients from noncolonized patients. In addition, the CAM-TABM level was directly related to mRNA expression for IL-4 but not IFN-γ. These results reinforce the view that TABMs are associated with decreased CMI, immunoregulation, and the T-helper cell 2-type immune response.
PMCID: PMC1459633  PMID: 16603614
9.  Mannan as an antigen in cell-mediated immunity (CMI) assays and as a modulator of mannan-specific CMI. 
Infection and Immunity  1989;57(3):693-700.
Mannan (MAN) extracted from Candida albicans 20A was investigated for its potential as an antigen in the detection of cell-mediated immunity (CMI) in vivo and in vitro and for its ability to modulate CMI when administered intravenously (i.v.). CBA/J mice were either immunized as adults by the cutaneous inoculation of 10(6) viable blastoconidia or colonized as infants (primed) and then boosted cutaneously as adults. When immunized animals were footpad tested with MAN, highly significant delayed-type hypersensitivity (DH) responses were detected. The DH responses to MAN were of a greater magnitude than those noted with the same quantity of cell wall glycoprotein (GP), an ethylenediamine extract of the cell wall which contains both glucan and MAN. In contrast, GP was a better antigen for the detection of CMI responses in an in vitro lymphoproliferative assay with either spleen or lymph node cell suspensions. Mice treated with MAN i.v. prior to the initiation of immunization or between priming and secondary inoculations developed significantly suppressed DH reactions when tested with either MAN or GP. The lowest effective dose of MAN was 250 micrograms, maximum suppression occurred with 500 micrograms, and either dose given 1 week prior to immunization was suppressive. The suppression by MAN was specific for MAN or the MAN-containing GP. Responses to another unrelated candidal antigen, a membrane extract designated BEX, were relatively unaffected. MAN, therefore, was an effective antigen for the detection of CMI in vivo, and its administration i.v. created what appeared to be a MAN-specific suppression since it could be detected with both MAN and a MAN-containing extract from the cell wall. Caution must be exercised in the interpretation of these data, however, since the protein component of each of these extracts has not been characterized with respect to its potential role in the phenomena observed.
PMCID: PMC313164  PMID: 2917780
10.  Role of L3T4+ lymphocytes in protective immunity to systemic Candida albicans infection in mice. 
Infection and Immunity  1989;57(11):3581-3587.
Protective immunity to lethal Candida albicans challenge in vivo and activation of splenic macrophages with highly candidacidal activity in vitro were detected in mice infected with low-virulence agerminative yeast cells of the variant strain PCA-2, at a time when a strong delayed-type hypersensitivity (DTH) reaction to C. albicans occurred in the footpads of PCA-2-treated mice. The DTH reaction was transferable with spleen cell populations from these animals, and enrichment of splenic lymphocytes in L3T4+ cells significantly increased the footpad swelling. The reactivity transferred by L3T4+ cells was a radiosensitive (2,500 rads in vitro) phenomenon that required collaboration with radioresistant, silica-sensitive syngeneic cells in the host and was inhibited by treatment of recipient mice with antibodies to the L3T4 antigen or murine gamma interferon. In vitro, the PCA-2-immune L3T4+ cells produced various lymphokine activities upon incubation with C. albicans, including gamma interferon and granulocyte-macrophage colony-stimulating factor. Anti-L3T4 monoclonal antibody treatment of PCA-2-infected mice significantly impaired their footpad reaction and resistance to C. albicans, as shown by increased recovery of yeast cells from the kidneys of anti-L3T4-treated mice. These results suggested that the mechanisms of anti-Candida resistance induced by PCA-2 may involve specific induction of a DTH response mediated by inflammatory L3T4+ T cells and lymphokine-activated phagocytic effectors. However, the survival rate of the PCA-2-immune mice challenged with C. albicans was not significantly modified by administration of the anti-L3T4 antibody, thus allowing for the conclusion that compensatory mechanisms lead to considerable anti-Candida resistance when the activity of L3T4+ cells is deficient.
PMCID: PMC259871  PMID: 2572556
11.  A mannoprotein constituent of Candida albicans that elicits different levels of delayed-type hypersensitivity, cytokine production, and anticandidal protection in mice. 
Infection and Immunity  1994;62(12):5353-5360.
To identify major immunogenic constituents of Candida albicans, the effect of a mannoprotein fraction (MP-F2) on the elicitation of a delayed-type hypersensitivity (DTH) reaction, cytokine production, and protection from a virulent Candida challenge in a mouse candidiasis model was studied. In mice immunized with whole cells of a low-virulence strain of C. albicans and thus protected against a challenge with a highly virulent strain of this fungus, MP-F2 was able to elicit a strong DTH response that was accompanied by splenocyte proliferation in vitro in the presence of Candida antigen. The supernatants of MP-F2-stimulated splenocyte cultures contained gamma interferon (IFN-gamma, a typical CD4+ T helper-1 (Th1) cytokine, but no interleukin-4, (IL-4), a typical CD4+ Th2 cytokine. IFN-gamma was produced by CD4+ cells, and its level could be greatly increased by the addition of anti-IL-4 or, mostly, anti-IL-10 antibodies to the CD4+ cell cultures. Upon a suitable schedule of immunization, MP-F2 was also able to induce a vigorous DTH response in Candida-uninfected mice, a response that could be efficiently transferred into naive recipients by CD4+ cells from the spleens of MP-F2-immunized mice. The immunization described above also conferred to mice a low degree of protection against a virulent Candida challenge, both in terms of median survival time and in the number of Candida cells in the kidney. However, while DTH induction by MP-F2 was as strong as that induced by whole cells, MP-F2-induced protection was significantly weaker than that conferred by Candida whole-cell immunization. Mice immunized with either MP-F2 or Candida whole cells had an inverted ratio between the number of CD4+ splenocytes producing IFN-gamma and that of cells producing IL-4, compared with nonimmunized animals. However, the number of IL-4-producing CD4+ cells was significantly higher in MP-F2-vaccinated, weakly protected mice than in Candida whole-cell-vaccinated, highly protected animals. Overall, our data suggest that the MP-F2 fraction contains one or more major immunogens of C. albicans which are capable of interfering with the balance of CD4+ Th1 and Th2 responses that is so critical in the outcome of host-Candida relationship and are thus potentially relevant in the mechanisms of Candida-specific DTH regulation and protection.
PMCID: PMC303275  PMID: 7960114
12.  Local Production of Chemokines during Experimental Vaginal Candidiasis 
Infection and Immunity  1999;67(11):5820-5826.
Recurrent vulvovaginal candidiasis, caused by Candida albicans, is a significant problem in women of childbearing age. Although cell-mediated immunity (CMI) due to T cells and cytokines is the predominant host defense mechanism against C. albicans at mucosal tissue sites, host defense mechanisms against C. albicans at the vaginal mucosa are poorly understood. Based on an estrogen-dependent murine model of vaginal candidiasis, our data suggest that systemic CMI is ineffective against C. albicans vaginal infections. Thus, we have postulated that local immune mechanisms are critical for protection against infection. In the present study, the kinetic production of chemokines normally associated with the chemotaxis of T cells, macrophages (RANTES, MIP-1α, MCP-1), and polymorphonuclear neutrophils (MIP-2) was examined following intravaginal inoculation of C. albicans in estrogen-treated or untreated mice. Results showed significant increases in MCP-1 protein and mRNA in vaginal tissue of infected mice as early as 2 and 4 days postinoculation, respectively, that continued through a 21-day observation period, irrespective of estrogen status. No significant changes were observed with RANTES, MIP-1α, or MIP-2, although relatively high constitutive levels of RANTES mRNA and MIP-2 protein were observed. Furthermore, intravaginal immunoneutralization of MCP-1 with anti-MCP-1 antibodies resulted in a significant increase in vaginal fungal burden early during infection, suggesting that MCP-1 plays some role in reducing the fungal burden during vaginal infection. However, the lack of changes in leukocyte profiles in vaginal lavage fluids collected from infected versus uninfected mice suggests that MCP-1 functions to control vaginal C. albicans titers in a manner independent of cellular chemotactic activity.
PMCID: PMC96961  PMID: 10531235
13.  Immunopathogenesis of recurrent vulvovaginal candidiasis. 
Clinical Microbiology Reviews  1996;9(3):335-348.
Recurrent vulvovaginal candidiasis (RVVC) is a prevalent opportunistic mucosal infection, caused predominantly by Candida albicans, which affects a significant number of otherwise healthy women of childbearing age. Since there are no known exogenous predisposing factors to explain the incidence of symptomatic vaginitis in most women with idiopathic RVVC, it has been postulated that these particular women suffer from an immunological abnormality that prediposes them to RVVC. Because of the increased incidence of mucosal candidiasis in individuals with depressed cell-mediated immunity (CMI), defects in CMI are viewed as a possible explanation for RVVC. In this review, we attempt to place into perspective the accumulated information regarding the immunopathogenesis of RVVC, as well as to provide new immunological perspectives and hypotheses regarding potential immunological deficiencies that may predispose to RVVC and potentially other mucosal infections by the same organism. The results of both clinical studies and studies in an animal model of experimental vaginitis suggest that systemic CMI may not be the predominant host defense mechanism against C. albicans vaginal infections. Rather, locally acquired mucosal immunity, distinct from that in the peripheral circulation, is now under consideration as an important host defense at the vaginal mucosa, as well as the notion that changes in local CMI mechanism(s) may predispose to RVVC.
PMCID: PMC172897  PMID: 8809464
14.  Characterization of cellular infiltrates and cytokine production during the expression phase of the anticryptococcal delayed-type hypersensitivity response. 
Infection and Immunity  1993;61(7):2854-2865.
Cryptococcosis, an increasingly important opportunistic infection caused by the encapsulated yeast-like organism Cryptococcus neoformans, is limited by an anticryptococcal cell-mediated immune (CMI) response. Gaining a thorough understanding of the complex anticryptococcal CMI response is essential for developing means of controlling infections with C. neoformans. The murine cryptococcosis model utilizing footpad swelling to cryptococcal antigen (delayed-type hypersensitivity [DTH]) has proven to be a valuable tool for studying the induction and regulation of the anticryptococcal CMI response, but this technique has limitations with regard to evaluating the role of the final effector cells recruited by an ongoing CMI response. The purpose of this study was to assess the types of cells and cytokines induced into the site of cryptococcal antigen deposition in C. neoformans-infected and -immunized mice compared with those for control mice. We used a gelatin sponge implant model to examine the cells and cytokines present at the site of an anticryptococcal DTH response. Sponges implanted in infected mice and injected with cryptococcal culture filtrate antigen (CneF) 24 h before assessment had significantly increased numbers of infiltrating leukocytes compared with saline-injected sponges in the same animals. Exaggerated influxes of neutrophils and mononuclear cells were the major contributors to the increase in total numbers of cells in the DTH-reactive sponges. The numbers of CD4+ and LFA-1+ cells were found to be significantly increased in the CneF-injected sponges of infected and immunized mice over the numbers in control sponges. The numbers of large granular lymphocytes were also increased in DTH-reactive sponges compared with control sponges. Gamma interferon, interleukin 2 (IL-2), and IL-5 are clearly relevant cytokines in the anticryptococcal CMI response, since they were produced in greater amounts in the CneF-injected sponges from C. neoformans-infected and -immunized mice than in control sponges. IL-4 was not associated with the expression of DTH to cryptococcal antigen. The gelatin sponge model is an excellent tool for studying cells and cytokines involved in specific CMI responses.
PMCID: PMC280931  PMID: 8514388
15.  Differences in Components at Delayed-Type Hypersensitivity Reaction Sites in Mice Immunized with Either a Protective or a Nonprotective Immunogen of Cryptococcus neoformans 
Infection and Immunity  2002;70(2):591-600.
Cell-mediated immunity is the major protective mechanism against Cryptococcus neoformans. Delayed swelling reactions, i.e., delayed-type hypersensitivity (DTH), in response to an intradermal injection of specific antigen are used as a means of detecting a cell-mediated immune (CMI) response to the antigen. We have found previously that the presence of an anticryptococcal DTH response in mice is not always indicative of protection against a cryptococcal infection. Using one immunogen that induces a protective anticryptococcal CMI response and one that induces a nonprotective response, we have shown that mice immunized with the protective immunogen undergo a classical DTH response characterized by mononuclear cell and neutrophil infiltrates and the presence of gamma interferon and NO. In contrast, immunization with the nonprotective immunogen results in an influx of primarily neutrophils and production of tumor necrosis factor alpha (TNF-α) at the DTH reaction site. Even when the anticryptococcal DTH response was augmented by blocking the down-regulator, CTLA-4 (CD152), on T cells in the mice given the nonprotective immunogen, the main leukocyte population infiltrating the DTH reaction site is the neutrophil. Although TNF-α is increased at the DTH reaction site in mice immunized with the nonprotective immunogen, it is unlikely that TNF-α activates the neutrophils, because the density of TNF receptors on the neutrophils is reduced below control levels. Uncoupling of DTH reactivity and protection has been demonstrated in other infectious-disease models; however, the mechanisms differ from our model. These findings stress the importance of defining the cascade of events occurring in response to various immunogens and establishing the relationships between protection and DTH reactions.
PMCID: PMC127722  PMID: 11796587
16.  Vaginal and Oral Epithelial Cell Anti-Candida Activity  
Infection and Immunity  2002;70(12):7081-7088.
Candida albicans is the causative agent of acute and recurrent vulvovaginal candidiasis (VVC), a common mucosal infection affecting significant numbers of women in their reproductive years. While any murine host protective role for cell-mediated immunity (CMI), humoral immunity, and innate resistance by neutrophils against the vaginal infection appear negligible, significant in vitro growth inhibition of Candida species by vaginal and oral epithelial cell-enriched cells has been observed. Both oral and vaginal epithelial cell anti-Candida activity has a strict requirement for cell contact to C. albicans with no role for soluble factors, and oral epithelial cells inhibit C. albicans through a cell surface carbohydrate moiety. The present study further evaluated the inhibitory mechanisms by murine vaginal epithelial cells and the fate of C. albicans by oral and vaginal epithelial cells. Similar to human oral cells, anti-Candida activity produced by murine vaginal epithelial cells is unaffected by enzymatic cleavage of cell surface proteins and lipids but sensitive to periodic acid cleavage of surface carbohydrates. Analysis of specific membrane carbohydrate moieties, however, showed no role for sulfated polysaccharides, sialic acid residues, or glucose and mannose-containing carbohydrates, also similar to oral cells. Staining for live and dead Candida in the coculture with fluorescein diacetate (FDA) and propidium iodide (PI), respectively, showed a clear predominance of live organisms, suggesting a static rather than cidal action. Together, the results suggest that oral and vaginal epithelial cells retard or arrest the growth rather than kill C. albicans through an as-yet-unidentified carbohydrate moiety in a noninflammatory manner.
PMCID: PMC133056  PMID: 12438389
17.  Enhanced immune responses in mice treated with penicillin-tetracycline or trimethoprim-sulfamethoxazole when colonized intragastrically with Candida albicans. 
Immune consequences of gastrointestinal colonization of CD-1 and CBA/J mice with Candida albicans in the presence or absence of continuous antibiotic treatment with penicillin-tetracycline or trimethoprimsulfamethoxazole were investigated. Intubation with C. albicans in the absence of antibiotics resulted in the induction of low but detectable delayed-type hypersensitivity (DTH), demonstrable by footpad testing with a C. albicans wall glycoprotein (GP), and in the stimulation of a moderate level of protective immunity, demonstrable by intravenous (i.v.) challenge. DTH to a membrane extract, BEX, could not be detected in such animals. However, animals colonized in the presence of antibiotics and then inoculated cutaneously prior to being tested for DTH or protective immunity developed significantly enhanced levels of DTH to GP and BEX and were protected to an even greater extent than animals colonized in the absence of antibiotics who were not inoculated cutaneously. The priming effect of colonization, particularly with respect to the antigen GP, was also obvious from an enzyme-linked immunosorbent assay for GP-specific antibody with sera of mice surviving the i.v. challenge, in that GP-specific antibody was present in the highest titers in colonized animals that had been inoculated cutaneously prior to i.v. challenge. While the antibiotics promoted higher levels of colonization, as evidenced by stomach and fecal cultures of intubated mice, antibiotic administration was not necessary for the induction of C. albicans-specific responses. Moreover, contrary to reports in the literature, antibiotic administration had no adverse effect on the immune responses measured. Females were innately more resistant than males to i.v. challenge with C. albicans, but each sex was capable of developing protective immunity of equal intensity in response to colonization or immunization by cutaneous challenge.
PMCID: PMC174816  PMID: 3300536
18.  Effectiveness of a Vaccine Composed of Heat-Killed Candida albicans and a Novel Mucosal Adjuvant, LT(R192G), against Systemic Candidiasis 
Infection and Immunity  1999;67(2):826-833.
The incidence of fungal infections caused by the opportunistic yeast Candida albicans has increased significantly in recent years. The ability to vaccinate selected patients against the organism would be advantageous. In this paper we describe a potential anti-C. albicans vaccine consisting of heat-killed C. albicans (HK-CA) in combination with the novel mucosal adjuvant LT(R192G), a genetically detoxified form of the heat-labile toxin of enterotoxigenic Escherichia coli. Groups of male CBA/J mice were immunized intranasally on three occasions at weekly intervals with 2 × 107 HK-CA per dose, alone or in conjunction with 10 μg of LT(R192G) per dose. Two weeks following the last application of antigen, some animals were challenged intravenously (i.v.) with 104, 105, or 106 viable C. albicans to assess protection as measured by survival and/or culture. Some groups of animals were footpad tested with C. albicans mannan to assess delayed-type hypersensitivity (DTH), and all the animals were bled for antibody assays. In two independent studies, all the animals immunized with HK-CA plus LT(R192G) were able to eradicate 104 C. albicans completely, as determined by kidney culture 4 weeks after challenge. Animals immunized with HK-CA only had reduced levels of C. albicans compared to the adjuvant or saline-only control. Greatly enhanced survival was observed when mice immunized with HK-CA plus LT(R192G) were challenged with 105 live C. albicans as well. Animals immunized with HK-CA plus LT(R192G) developed a significant DH response, while those given HK-CA alone developed only marginal DH responses. High immunoglobulin G (IgG) levels to cytoplasmic antigens developed in mice immunized with HK-CA plus LT(R192G), but they were found only after i.v. challenge. Addition of adjuvant shifted the antibody isotype production in i.v.-challenged animals to a response dominated by IgG2a. Clearly, intranasal immunization with killed C. albicans in conjunction with LT(R192G) afforded significant levels of protection. This novel approach offers new possibilities for the development of an effective vaccine against candidiasis for use in humans.
PMCID: PMC96393  PMID: 9916097
19.  Effects of Tumor Necrosis Factor Alpha on Dendritic Cell Accumulation in Lymph Nodes Draining the Immunization Site and the Impact on the Anticryptococcal Cell-Mediated Immune Response  
Infection and Immunity  2003;71(1):68-74.
Cell-mediated immune (CMI) responses and tumor necrosis factor alpha (TNF-α) have been shown to be essential in acquired protection against Cryptococcus neoformans. Induction of a protective anticryptococcal CMI response includes increases in dendritic cells (DC) and activated CD4+ T cells in draining lymph nodes (DLN). During the expression phase, activated CD4+ T cells accumulate at a peripheral site where cryptococcal antigen is injected, resulting in a classical delayed-type hypersensitivity (DTH) reaction. Induction of a nonprotective anticryptococcal CMI response results in no significant increases in the numbers of DC or activated CD4+ T cells in DLN. This study focuses on examining the role of TNF-α in induction of protective and nonprotective anticryptococcal CMI responses. We found that neutralization of TNF-α at the time of immunization with the protective immunogen (i) reduces the numbers of Langerhans cells, myeloid and lymphoid DC, and activated CD4+ T cells in DLN and (ii) diminishes the total numbers of cells, the numbers of activated CD4+ T cells, and amount of gamma interferon at the DTH reaction site. Although TNF-α neutralization during induction of the nonprotective CMI response had little effect on cellular and cytokine parameters measured, it did cause a reduction in footpad swelling when mice received challenge in the footpad. Our findings show that TNF-α functions during induction of the protective CMI response by influencing the accumulation of all three DC subsets into DLN. Without antigen stimulated DC in DLN, activated CD4+ T cells are not induced and thus not available for the expression phase of the CMI response.
PMCID: PMC143367  PMID: 12496150
20.  Chlamydia trachomatis Infection Does Not Enhance Local Cellular Immunity against Concurrent Candida Vaginal Infection 
Infection and Immunity  2001;69(5):3451-3454.
Although Th1-type cell-mediated immunity (CMI) is the predominant host defense mechanism against mucosal Candida albicans infection, CMI against a vaginal C. albicans infection in mice is limited at the vaginal mucosa despite a strong Candida-specific Th1-type response in the draining lymph nodes. In contrast, Th1-type CMI is highly effective against an experimental Chlamydia trachomatis genital tract infection. This study demonstrated through two independent designs that a concurrent Candida and Chlamydia infection could not accelerate or modulate the anti-Candida CMI response. Together, these results suggest that host responses to these genital tract infections are independent and not influenced by the presence of the other.
PMCID: PMC98310  PMID: 11292774
21.  Vaginal yeast colonisation, prevalence of vaginitis, and associated local immunity in adolescents 
Objectives: To evaluate point prevalence vaginal yeast colonisation and symptomatic vaginitis in middle adolescents and to identify relation of these yeast conditions with reproductive hormones, sexual activity, sexual behaviours, and associated local immunity.
Methods: Middle adolescent females (n = 153) were evaluated for sexually transmitted infections (STIs), asymptomatic yeast colonisation, and symptomatic vulvovaginal candidiasis (VVC) by standard criteria. Also evaluated were local parameters, including vaginal associated cytokines, chemokines, and antibodies, vaginal epithelial cell antifungal activity, and Candida specific peripheral blood lymphocyte responses. Correlations between yeast colonisation/vaginitis and local immunomodulators, reproductive hormones, douching, sexual activity, condom use, and STIs were identified.
Results: Rates of point prevalence asymptomatic yeast colonisation (22%) were similar to adults and similarly dominated by Candida albicans, but with uncharacteristically high vaginal yeast burden. In contrast with the high rate of STIs (18%), incidence of symptomatic VVC was low (<2%). Immunological properties included high rates of Candida specific systemic immune sensitisation, a Th2 type vaginal cytokine profile, total and Candida specific vaginal antibodies dominated by IgA, and moderate vaginal epithelial cell anti-Candida activity. Endogenous reproductive hormones were in low concentration. Sexual activity positively correlated with vaginal yeast colonisation, whereas vaginal cytokines (Th1, Th2, proinflammatory), chemokines, antibodies, contraception, douching, or condom use did not.
Conclusion: Asymptomatic vaginal yeast colonisation in adolescents is distinct in some ways with adults, and positively correlates with sexual activity, but not with local immunomodulators or sexual behaviours. Despite several factors predictive for VVC, symptomatic VVC was low compared to STIs.
PMCID: PMC1758371  PMID: 14755036
22.  Role for Dendritic Cells in Immunoregulation during Experimental Vaginal Candidiasis  
Infection and Immunity  2006;74(6):3213-3221.
Vulvovaginal candidiasis (VVC) caused by the commensal organism Candida albicans remains a significant problem among women of childbearing age, with protection against and susceptibility to infection still poorly understood. While cell-mediated immunity by CD4+ Th1-type cells is protective against most forms of mucosal candidiasis, no protective role for adaptive immunity has been identified against VVC. This is postulated to be due to immunoregulation that prohibits a more profound Candida-specific CD4+ T-cell response against infection. The purpose of this study was to examine the role of dendritic cells (DCs) in the induction phase of the immune response as a means to understand the initiation of the immunoregulatory events. Immunostaining of DCs in sectioned murine lymph nodes draining the vagina revealed a profound cellular reorganization with DCs becoming concentrated in the T-cell zone throughout the course of experimental vaginal Candida infection consistent with cell-mediated immune responsiveness. However, analysis of draining lymph node DC subsets revealed a predominance of immunoregulation-associated CD11c+ B220+ plasmacytoid DCs (pDCs) under both uninfected and infected conditions. Staining of vaginal DCs showed the presence of both DEC-205+ and pDCs, with extension of dendrites into the vaginal lumen of infected mice in close contact with Candida. Flow cytometric analysis of draining lymph node DC costimulatory molecules and activation markers from infected mice indicated a lack of upregulation of major histocompatibility complex class II, CD80, CD86, and CD40 during infection, consistent with a tolerizing condition. Together, the results suggest that DCs are involved in the immunoregulatory events manifested during a vaginal Candida infection and potentially through the action of pDCs.
PMCID: PMC1479243  PMID: 16714548
23.  T lymphocytes in the murine vaginal mucosa are phenotypically distinct from those in the periphery. 
Infection and Immunity  1996;64(9):3793-3799.
The results from both clinical studies of women with recurrent vulvovaginal candidiasis and a murine model of experimental vaginitis indicate that systemic cell-mediated immunity may not represent a dominant host defense mechanism against vaginal infections by Candida albicans. Recent experimental evidence indicates the presence of local vaginal immune reactivity against C. albicans. The present study was designed to examine T-lymphocyte subpopulations in the vaginal mucosae of naive CBA/J mice. Vaginal lymphocytes (VL) were isolated by collagenase digestion of whole vaginal tissues. Cell populations were identified by flow cytometry, and the results were compared with those for both lymph node cells (LNC) and peripheral blood lymphocytes (PBL). The results of flow cytometry showed that 45% +/- 10% of lymphocytes in the vaginal mucosa are CD3+ compared with 75% +/- 5% in LNC and 50% +/- 5% in PBL. The majority (85%) of CD3+ VL are CD4+ and express the alpha/beta T-cell receptor (TCR), similar to the results for LNC and PBL. In contrast to LNC and PBL, VL contain a significantly higher percentage (15 to 20%) of gamma/delta TCR+ cells, 80% or more of which appear to express CD4. In addition, while CD4-CD8 cell ratios in LNC and PBL were 3:1 and 6:1, respectively, only 1% of VL expressed CD8, resulting in a CD4-CD8 cell ratio of > 100:1. Finally, while LNC and PBL recognized two epitope-distinct (GK 1.5 and 2B6) anti-CD4 antibodies, VL recognized only 2B6 anti-CD4 antibodies. Further analysis of VL showed that Thy-1 cells, but not CD4 cells, were reduced after intravaginal injection of complement-fixing anti-Thy-1.2 and GK 1.5 anti-CD4 antibodies, respectively. Taken together, these data suggest that T lymphocytes in the vaginal mucosae of mice are phenotypically distinct from those in the periphery and that CD4+ VL have an uncharacteristic or atypical expression of the CD4 receptor.
PMCID: PMC174295  PMID: 8751931
24.  CTLA-4 Down-Regulates the Protective Anticryptococcal Cell-Mediated Immune Response 
Infection and Immunity  2000;68(8):4624-4630.
Cell-mediated immune (CMI) responses defined by delayed-type hypersensitivity (DTH) reactivity to cryptococcal culture filtrate antigen (CneF) can be either protective or nonprotective against an infection with Cryptococcus neoformans. The protective and nonprotective anticryptococcal DTH responses are induced by different immunogens and have differing activated-T-cell profiles. This study examined the effects of blockade of the interaction between cytotoxic T lymphocyte antigen 4 (CTLA-4) and its ligands B7-1 (CD80) and B7-2 (CD86) on the anticryptococcal DTH responses and protection. We found that CTLA-4 blockade at the time of immunization with the immunogen that induces the protective response, CneF, in complete Freund's adjuvant (CFA) or the immunogen that induces the nonprotective response, heat-killed cryptococcal cells (HKC), enhanced anticryptococcal DTH reactivity. In contrast, blocking CTLA-4 after the immune response was induced failed to enhance responses. Blockade of CTLA-4 in an infection model resulted in earlier development of the anticryptococcal CMI response than in control mice. Concomitant with increases in DTH reactivity in mice treated with anti-CTLA-4 Fab fragments at the time of immunization, there were decreases in cryptococcal CFU in lungs, spleens, and brains compared to controls. Blockade of CTLA-4 resulted in long-term protection, as measured by significantly increased survival times, only in mice given the protective immunogen, CneF-CFA. Anti-CTLA-4 treatment did not shift the response induced by the nonprotective immunogen, HKC, to a long-term protective one. Our data indicate that blockade of CTLA-4 interactions with its ligands may be useful in enhancing host defenses against C. neoformans.
PMCID: PMC98393  PMID: 10899865
25.  Effects of Cryptococcus neoformans-specific suppressor T cells on the amplified anticryptococcal delayed-type hypersensitivity response. 
Infection and Immunity  1991;59(1):29-35.
Cell-mediated immunity is an important host resistance mechanism against Cryptococcus neoformans, the etiological agent of cryptococcosis. Previous studies from our laboratory have shown that the anticryptococcal cell-mediated immune response as measured by delayed-type hypersensitivity (DTH) is down-regulated by a cascade of antigen-specific T suppressor (Ts) cells. Recently, we have identified a population of CD4 T cells that up-regulate the anticryptococcal DTH response (Tamp cells). The Tamp cells are found in the spleens of donor mice at 6 days after immunization with cryptococcal antigen, and they amplify the anticryptococcal DTH response when transferred to syngeneic recipients at the time of immunization of the recipients. In this study, we determined the effects of C. neoformans-specific Ts cells on the induction of the Tamp cells in the Tamp cell-donor mice and on the induction and expression of the amplified anticryptococcal DTH response in the Tamp cell-recipient mice. When cryptococcal-specific Ts1 cells were given at the time of immunization of the Tamp cell-donor mice, induction of Tamp cells was inhibited. In contrast, when Ts1 cells were given at the time of adoptive transfer of Tamp cells, the recipients displayed amplified DTH responses, indicating that Ts1 cells do not affect the Tamp cells' function once the Tamp cells have been produced. C. neoformans-specific Ts2 cells given at the time of either immunization or footpad challenge of the Tamp cell-recipient mice did not alter, to any measurable extent, the amplified DTH response. These results indicate that in addition to amplifying the anticryptococcal DTH response, Tamp cells may protect the anticryptococcal TDH cells from suppression by C. neoformans-specific Ts cells, much like contrasuppressor cells do in other systems. However, further characterization of the Tamp cells revealed that they are not adherent to Viscia villosa lectin, indicating that the anticryptococcal Tamp cells do not have this characteristic in common with contrasuppressor cells of other antigen systems.
PMCID: PMC257701  PMID: 1824761

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