|Home | About | Journals | Submit | Contact Us | Français|
The whole serum complement and its components were studied in 24 recipients of 27 renal homografts. In 12 of 13 instances in which homograft rejection was diagnosed, it was accompanied by significant declines in CH50, IA50, C4, and C3 levels, and to a lesser degree in C1 and C2 levels. Fourteen patients had normal graft function during the postoperative course of study, and in 13 of the 14 the complement levels were within the normal range throughout. In two recipients with systemic lupus erythematosus, very low initial complement levels increased to normal levels following removal of the native kidneys, splenectomy, and the provision of a well-functioning homograft. Anticomplement activity and elevated titers of C1 and C3 inactivators were observed in some patients, but these did not correlate with the changes in CH50. The findings confirm that the complement system participates in renal homograft rejection.
There is accumulating evidence that serum complement participates in the rejection of transplanted tissues and organs. 2, 4, 8, 9, 11 In human recipients of renal homografts, Guiney and associates9 and Austen and Russell2 described a drop in CH50 and particularly C2 levels coincident with rejection. Levine and associates11 have confirmed falls in whole complement with graft repudiation. Austen and Russell2 and Carpenter and associates4 have demonstrated that decreases in either whole complement or its components may be delayed until sometime after clinically evident rejection.
In the present study, we have analyzed the whole complement and its components after human renal transplantation in order to clarify further how various parts of the complement system are affected during convalescence, with and without rejection episodes.
The ages of the 24 patients ranged from 11 to 46 years, and were in terminal renal failure due to chronic glomerulonephritis (16 instances), chronic pyelonephritis (2), polycystic kidney disease (2), systemic lupus erythematosus (SLE) (2), familial medullary cystic disease (1), and cystinosis (1). Immunosuppressive therapy was provided by a triple-drug regimen consisting of azathioprine, prednisone, and antilymphocyte globulin (ALG).18
There were 27 transplantations in the 24 recipients. Fifteen of the grafts were from related donors, and the other 12 were from cadavers. The patients were a complicated group in that six were receiving second homografts after having rejected their first ones. One recipient underwent both first and second transplants during the period of study. Another underwent a second and third transplantation. A third recipient was given his third and fourth kidneys. In about two thirds of the cases, the native patients’ kidneys were removed in conjunction with splenectomy, and in the other third, the diseased kidneys were not disturbed.
Blood samples were permitted to clot at room temperature for approximately one hour. Serum was separated by centrifugation at 3,000 rpm for 15 minutes at 0° to 4° C. and stored at –70° C. until used. All sera from an individual patient or control subject were analyzed simultaneously.
Total complement activity was measured as hemolytic complement activity (CH50) according to Mayer12 and with the immune adherence hemagglutination (IA50) method of Nishioka.14 The C1, C4, and C2 components were assayed by stoichiometric tube titration with the use of EAC4hu, EAC1gp, and EAC1hu C4hu cells at a concentration of 1.5 × 108 cells per milliliter, respectively.2, 13 The C3 activity was assayed by immune adherence15 with the use of EAC1hu 4hu 2hu cells.
Complement (CH50 and IA50) was measured in 250 normal people; the C1, C4, C2 and C3 were analyzed in 100 of them. In addition, three normal volunteers were studied weekly at the same time of day for six months, as it was demonstrated by Arata1 that daily fluctuations within 8 CH50 units might occur in an individual. The results are presented in Table I and Fig. 1.
Rejection was defined by elevations in blood urea nitrogen and serum creatinine or by falls in creatinine clearance or urine sodium concentration. Three of these findings on two consecutive days were required to establish the diagnosis.
Fourteen patients including one with SLE always had good renal function after transplantation with no sign of rejection. In this group, the pre- and postoperative complement levels were essentially within normal limits (Fig. 2), and in all but one patient, the fluctuations were no larger than in the normal volunteers. In the single exceptional case, transient moderate decreases in complement occurred two and six weeks after transplantation.
Seven of the patients including one with SLE had initially well-functioning grafts that suffered from rejection episodes. During these times, there was always a significant decrease in CH50 and IA50 titers (Fig. 3). The first four complement components showed different behavior patterns. The C1, C4, and C3 levels all dropped to subnormal values during the rejection episode with the most pronounced changes occurring for C4 and C3. The C2 also decreased but did not reach values below the normal range (Fig. 3).
Rejection episodes occurred in two patients at the same time as liver dysfunction, which was so severe that it ultimately caused death. Drops in the complement measures occurred to an extent not seen during rejection episodes without liver complications. Another patient developed severe rejection with marked complement changes six weeks after transplantation (Fig. 4). Following massive prednisone treatment, death ensued from encephalomyelitis two weeks later. At autopsy, it was interesting that the swollen homograft had virtually no histopathologic findings of rejection. In the remaining four patients, recovery of homograft function was accompanied by the complement levels returning to normal.
Three kidneys never functioned and probably underwent hyperacute rejection. Two of these grafts were transplanted consecutively to the same patient. Both recipients had preformed antibodies, although not against their donors. Two more transplants functioned well for a few hours but then shut down for 10 to 14 days before resuming significant urine excretion. A sixth graft became anuric two weeks after transplantation and was removed; the organ was edematous and had tubular necrosis but with little cellular infiltration.
After five of the foregoing six transplantations, there were definite and fluctuating decreases in CH50, IA50, C4, C3, and, to a lesser extent, C2 values. The C1 level remained essentially unchanged, sometimes with small variations. In one of the patients who experienced a hyperacute rejection episode, the complement levels remained unchanged.
The native kidneys and spleen were removed prior to renal transplantation. The lowest titers of CH50, IA50, C4, C3, and C2 were recorded before the bilateral nephrectomy. These titers slightly increased in the anephric state, and following successful transplantation, they rose to normal levels. Antibodies to DNA and heat-denatured DNA were detectable both before and after the bilateral nephrectomies. However, they disappeared within a few days after transplantation. At the same time, the LE test turned from slightly positive to negative.
After operation, one of the recipients had neither rejection nor complement depression (Fig. 5). The other patient suffered a rejection episode during which the CH50, IA50, and C4 levels decreased significantly and returned to normal concomitantly with reversal of the rejection; this course is included in Fig. 4.
Thirteen of the 24 patients became Australia (Au)-antigen positive after transplantation, and in 11, an increased ACA was demonstrated. The data of ACA were plotted against CH50 titers in Fig. 6. There was no correlation, suggesting that the ACA had no measurable effect on the in vivo complement system in these cases.
C1 and C3 inactivators were measured in six patients during normal renal homograft function and rejection. There was no correlation between CH50 and C1 and C3 inactivators under either circumstance (Fig. 6).
Complement and its components in the 14 homograft recipients who maintained good renal function remained continuously within normal range and were comparable to that of the normal volunteers. This stability, which has been noted in renal recipients by Austen and Russell2 and Gewurz and associates8 indicates that immunosuppressive therapy as such has no influence on the complement system.
In contrast, the development of postoperative rejection was invariably reflected by changes within the complement system. These occurred simultaneously with the development of the rejection rather than afterward, as has been reported by others.2, 4 There were depressions of CH50, IA50, C4, C3, and, to a lesser degree, C1 and C2. With reversal of rejection, the CH50 and the decreased components returned to normal levels.
It was previously reported by Austen and Russell2 that the C2 titers fell to half their preoperative values during rejection, Gewurz and co-workers,8 Carpenter and associates,4 and Levine and colleagues11 demonstrated a similar decrease of C2 β1C globulin and whole complement, respectively. None of these authors stressed the most impressive decrease of serum C4 complement component, although Carpenter and associates5 described a moderate hypercatabolism of radioactive C4 and C3 intravenously injected into renal allograft recipients undergoing rejection.
In addition to those instances in which the diagnosis of classical rejection was unequivocal, there were six cases of transient or permanent homograft failure in which the role of immunologic mechanisms was less clear as the result of the features of the clinical course. In five of the latter recipients, there were decreased levels of CH50, IA50, C4, and C3 during the period of graft nonfunction. In addition to an accelerated cell-mediated immunologic reaction, other possibilities for the complement depletion could be either by deposition in the glomeruli of antibodies to glomerular basement membrane or by deposition of circulating antigen-antibody complexes. Both of the latter reactions are complement-consuming.6, 7
The two patients with SLE were of special interest because the disease that destroyed their native kidneys was accompanied by complement changes similar to those of rejection. When first evaluated, both potential recipients had extremely low levels of CH50, IA50, C4, C2, and C3. Following bilateral nephrectomy, there was a slight elevation of complement but by no means to normal level. After provision of well-functioning renal homografts, the complement returned to normal level, at which it remained in one instance and became secondarily and transiently depressed in the other with the onset of rejection. The explanation for complement restoration by virtue of the homotransplantation is unclear.
An additional group of interesting patients was made up of the 13 who developed evidence of Australia antigenemia after transplantation. In 11 of these recipients, increases of anticomplementary activity (ACA) was found. In spite of the significant titers of ACA, these had no correlation with CH50. In addition, the C1 and C3 inactivators which were measured in six patients during normal graft function and rejection did not have any correlation with the complement levels.
Aided by research grants from the Vetcra ns Administration, by Grants No. RR-00051 and RR-00069 from the General Clinical Research Centers Program of the Division of Research Resources, National Institutes of Health, and by Grants No. AI-10176-01, AI-AM-08898, AM-07772, GM-01686, and HE-09110 of the United States Public Health Service.
*Hyland Laboratories. Los Angeles, Calif.