A possible role for the lymphocyte in the mechanism of eosinopoiesis has been examined. Procedures known to deplete or inactivate the pool of recirculating lymphocytes such as neonatal thymectomy, administration of antilymphocyte serum, and prolonged thoracic duct drainage, either singly or in combination, resulted in a highly significant reduction in the eosinophil response to trichinosis. Irradiated animals exposed to parasitic challenge did not develop eosinophilia unless reconstituted with lymphocytes as well as bone marrow cells. When "memory" cells were used instead of normal lymphocytes, a "secondary" type of eosinophil response was observed. Transfer of a primary eosinophilia was achieved adoptively with a population of living large lymphocytes from thoracic duct lymph and peripheral blood, but not with blood plasma or cell-free lymph. The potency of the active lymphocytes was not impaired by enclosing them in cell-tight diffusion chambers, indicating that they exerted an effect on bone marrow by agency of a diffusible factor. The demonstration of a role for lymphocytes in induction of the eosinophil response to this kind of stimulus supports the conclusion that eosinophilia belongs in the category of immunologic phenomena.
The phenomenon of eosinophilia was studied in rats using inoculation with Trichinella larvae as the experimental stimulus. Comparisons were made between the eosinophil response accompanying active infestation via the gastrointestinal tract and that resulting from parenteral inoculation of larvae or their products. A vigorous eosinophilia could be provoked by a single intravenous injection of intact parasites. In this circumstance the larvae lodged in the lungs causing an acute inflammatory reaction which led to their disintegration within 24 hr. Intraaortic injection also produced a significant response, whereas inoculation of the same number of parasites by the intramuscular, intraperitoneal, or subcutaneous routes did not cause eosinophilia. Eosinophilia likewise failed to develop if parasites were homogenized before intravenous injection, so that they were not arrested in the lungs. Antibody levels, as measured by a hemagglutination technique, using whole larval extract as antigen, did not correlate closely with the eosinophil response. The findings are interpreted as suggesting that increased eosinophil production is induced under some circumstances as a consequence of interaction between intact parasites and certain host cells in blood and tissue. No evidence was found for the existence of a specific constituent of the parasite capable of stimulating eosinophil production. Attention is directed to features of eosinophilia which fit with the concept that this phenomenon belongs in the category of immunologic reactions.
In studying the problem of the peculiar susceptibility of the kidney to coliform bacterial infection it was found that kidney tissue, unlike that of other organs, interferes with the ability of normal serum to destroy these organisms. The effect was attributable to strong anticomplementary activity, 5 to 15 times greater than that of other organs. Inactivation of complement by kidney tissue was found to have characteristics of a chemical reaction, the active principle being heat-labile, non-dialysable, and difficult to separate from tissue particles. Attempts to purify it or to obtain it in a soluble form usually resulted in great loss in activity. The component of complement affected was the fourth; i.e., that which is characterized by susceptibility to injury by ammonia. Similarities were found to exist between the conditions of ammonia formation and complement inactivation by kidney homogenates, the most notable being enhancement by phosphate and glutamine. The possibility is suggested that these findings may help to explain the vulnerability of the kidney to certain infections, especially those due to bacteria which are destroyed by the combined action of complement and antibody.
A study has been made of the effect of ureteral ligation on the susceptibility of the kidney to pyogenic infection. In most experiments a strain of E. coli was employed as the test organism, being injected intravenously in varying quantity either before or after ureteral ligation. A few experiments were also carried out with S. marcescens. Preliminary observations were made on the distribution and persistence of E. coli following its inoculation into the blood stream of normal rats. Rapid reduction in number of bacteria in the circulation occurred during the first 30 minutes, but bacteriemia persisted at a comparatively low level for at least 48 hours. Large proportions of the inoculated bacteria were arrested and apparently destroyed in the liver, spleen, and lungs. Comparatively small numbers were deposited in the kidneys; nevertheless, these continued to be demonstrable during the 1st week, without notable tendency to increase or decrease, then disappeared during the 2nd week. There was no acceleration in rate of disposal of the bacteria in the kidney when a second injection was made 1 week after the first. In rats with one ureter ligated the number of bacteria lodging in the kidneys after intravenous inoculation did not differ from that found in normal animals. It appears, therefore, that the increased susceptibility of the obstructed kidney to infection via the blood stream is not attributable to an increased trapping of circulating bacteria. 4 to 6 hours after the intravenous injection, however, an increased number of bacteria could be demonstrated in the obstructed kidney, apparently due to local multiplication, and by the end of 24 hours purulent infection was usually obvious. A comparatively large number of bacteria was required to cause infection, even in the kidney with obstruction. This appeared to be related to the small proportion of the intravenous inoculum which lodged in the kidney initially. Although bacteria could be demonstrated in the normal kidney for a week or more following intravenous injection it was not possible to induce active infection with equal regularity by ligating the ureter throughout this time. During the first 3 days the majority of obstructed kidneys developed infection, but after 5 or more days this occurred in only a small proportion of animals so treated. The reason for the difference, in relation to interval between intravenous injection and time of ligation, is not apparent. When the ureter was ligated but no intravenous injection of bacteria was given, staphylococcal infection developed in the obstructed kidney within 2 weeks in about one-third of the animals. Reasons are given for the belief that this was blood-borne infection, and not the result of contamination at the time of operation. Staphylococci were not recovered from the normal rat kidney. These "spontaneous" staphylococcal infections seldom developed when E. coli was injected intravenously at the time of ureteral ligation.
Injection of extracts or suspensions of various rabbit tissues was found to be without effect upon the body temperature of normal rabbits. Occasionally, extracts of bone marrow produced transient fever, and saline extracts of acute inflammatory lesions of the Shwartzman and Arthus types were found to produce fever when injected intravenously. Suspensions or extracts of polymorphonuclear leukocytes collected from sterile peritoneal exudates contain a heat-labile substance which produced fever whereas those of erythrocytes, macrophages, and lymphocytes failed to do so. The cell-free supernatant fluid of sterile peritoneal exudates obtained at the stage when polymorphonuclear leukocytes predominate also proved capable of producing fever.
Further studies on fever production by injection of leukocyte extracts or cell-free supernatant fluids from peritoneal exudates in rabbits are reported. Granulocytes collected from peripheral blood or from pleural exudates contain a heat-labile pyrogenic substance. The material in extracts of leukocytes and in peritoneal fluids, which causes fever, is destroyed by heating for 30 minutes at 90°C. at pH 7.2 and at 70°C. at pH 4.5. It is active in producing fever over a pH range of 2.0 to 10.5 and maintains potency for as long as 6 months at 4°C. The fever-producing substance in leukocyte extracts is not dialyzable. Its activity is not destroyed by trypsin, chymotrypsin, or ribonuclease. No evidence of plasma activator or inhibitor was detected. Significant temperature elevation in the rabbit was effected by a quantity of leukocyte extract containing 0.76 mg. protein and 0.054 mg. polysaccharide. The febrile response produced by the material under study was compared with that of Menkin's pyrexin as well as with that of bacterial pyrogens. Several significant differences were noted. The properties of pyrexin are similar to those of bacterial pyrogens. Amidopyrine suppressed the febrile response to injection of leukocyte extracts, whereas neither amidopyrine nor cortisone influenced the appearance of pyrogenic material in induced peritoneal exudates. Peritoneal fluids collected from rabbits made leukopenic by HN2 were found to contain a fever-promoting substance. Its character has yet to be determined. It is concluded that there is present in polymorphonuclear leukocytes of rabbits a heat-labile factor capable of producing fever in rabbits and that the leukocyte is probably not the only source of such a factor.
In experiments designed to elucidate the mechanism by which tolerance to bacterial pyrogens is developed, the following observations were made: 1. Animals whose febrile reactions to bacterial pyrogens were markedly diminished, as a result of repeated injections, showed increases in response following R-E blockade. 2. Pyrogenic substances disappeared from the circulating blood more rapidly in rabbits rendered pyrogen-tolerant than in normal animals. Lack of specificity was shown by the fact that rabbits previously injected with Eberthella typhosa bacterial vaccine were able to remove the pyrogens of Serratia marcescens and Pseudomonas aeruginosa from their blood more rapidly than normal animals. 3. R-E blockade-retarded the speed of disappearance of pyrogens from the circulating blood of animals which had been rendered relatively tolerant by previous injections of these substances. A possible mechanism for the development of unresponsiveness to bacterial pyrogens is suggested.
In a study of the febrile responses of rabbits to repeated intravenous injections of pyrogenic substances from Eberthella typhosa, Serratia marcescens, and Pseudomonas aeruginosa, the following observations were made: 1. A characteristic pattern of response to daily injections of the same dose of pyrogenic material was noted. This consisted of a progressive diminution in febrile response during the 1st week or 10 days, after which an animal responded to each injection with approximately the same degree of fever, even when the injections were continued for several weeks. 2. Animals given injections of the same amount of pyrogenic material at semiweekly or weekly intervals showed some diminution in febrile reaction but the alteration was less pronounced than that in animals injected every day. 3. Pyrogen tolerance appeared to be lost quickly. Animals allowed to rest for approximately 3 weeks reacted to readministration of pyrogen with fever comparable with that which occurred after the first injection. 4. By gradually increasing the size of the daily dose of pyrogen a tolerance could be established such that a reduced, but still considerable, amount of pyrogen caused no fever whatever. 5. Rabbits that had been injected with S. marcescens or Ps. aeruginosa pyrogens showed a diminished febrile response to E. typhosa vaccine. 6. Passive transfer of the unresponsiveness to pyrogens could not be demonstrated. 7. Prevention of temperature elevations during the course of immunization by use of an antipyretic drug did not interfere with the development of tolerance to pyrogens. 8. A series of mechanically induced bouts of fever did not reduce the responsiveness to bacterial pyrogens.
In 6 patients with bacterial endocarditis studies were made of the bacterial content of arterial and venous blood. Paired samples were collected, approximately simultaneously, from two different locations in the circulatory system, and colony counts were determined. As many as 48 specimens were taken for culture during a single period of study. Venous blood was drawn not only from different locations in the extremities, but also from the superior and inferior venae cavae, the right auricle, and the hepatic and renal veins. As would be expected, colony counts were highest in arterial blood. Blood from the antecubital veins gave colony counts only slightly lower than arterial blood. In the femoral veins, on the other hand, there were appreciably fewer organisms. This difference is attributed to the type of tissues drained by the two veins. Colony counts in blood from the superior and inferior venae cavae were also lower than arterial counts, the ratio being comparable to that found in femoral vein blood. In the renal veins colony counts were only slightly below the arterial level indicating that few organisms are removed from the blood during passage through the kidneys. The greatest reduction in bacterial content was found in hepatic vein blood. In 3 of the 6 subjects this reduction amounted to more than 95 per cent, and in all subjects the difference was very considerable. Mixed venous blood in the right auricle of the heart gave colony counts which were usually one-half to two-thirds as high as in corresponding samples of arterial blood. An interesting finding in these studies was a remarkable constancy of the bacterial content of arterial blood, during periods of 1 or 2 hours. Despite the fact that a considerable portion of the bacteria which leave the heart in arterial blood appear to be removed during a single circuit of the body, the number of bacteria in successive samples of arterial blood shows little change. This indicates that in bacterial endocarditis organisms are discharged into the blood from the endocardial vegetations at a comparatively even rate, rather than in a haphazard fashion as a result of the breaking off of infected particles.
1. The agglutination of human erythrocytes and the precipitation of the blood group A substance by Type XIV antipneumococcus horse serum are properties of the specific anticarbohydrate immune bodies in the serum. 2. Absorption of Type XIV antipneumococcus horse serum with the homologous bacterial polysaccharide removes the agglutinins for human erythrocytes as well as the precipitins for the group A substance. 3. Absorption of Type XIV antipneumococcus horse serum with the group A substance markedly diminishes the ability of the serum to agglutinate erythrocytes of all groups. 4. Absorption of Type XIV antipneumococcus horse serum with human erythrocytes causes a marked diminution in the precipitation with group A substance. 5. The chemical and immunological relationship between the specific substances of blood group A and the Type XIV Pneumococcus is discussed.