George J. Busch

Identity and Cytotoxic Capacity of Cells Infiltrating Renal Allografts

To determine the identity and cytotoxic capacity of lymphoid cells involved in allograft rejection, we studied viable, monodispersed cells recovered from 10 rejected human renal allografts. A heterogeneous population of cells including macrophages and both bone-marrow (B) and thymus-derived (T) lymphocytes accumulate in rejected grafts. Infiltrating lymphocytes exerted a specific cytolytic effect on 51Cr-labeled peripheral blood lymphocytes bearing donor antigens, ranging from 7 to 44 per cent specific lysis in nine of 10 cases. Cytolysis was closely correlated (r equal 0.91, p less than 0.05) with the histologica grade of cellular rejection but not with humoral rejection, suggesting that cytotoxic lymphocytes are an important element in cellular rejection. Limited fractionation studies showed that both T cells (in early rejection) and non-T cells (in late rejection) may produce cytotoxicity. Since as many as 50 per cent of cells recovered bore Fc receptors, the rejection process may also involve antibody-dependent target-cell lysis.

Treatment of acute renal allograft rejection with monoclonal anti-T12 antibody.

Nineteen patients with acute rejection of a renal allograft were treated with the monoclonal antibody anti-T12, directed against a determinant present on all post-thymic T cells. Seven patients had a good response, four had an equivocal response, and eight failed to respond. Histologic studies demonstrated that the good responders had primarily cellular rejection. The nonresponders included 4 patients with moderate-to-severe humoral rejection, one patient with an inadequate dose of antibody, one patient who withdrew before completing the study, and one patient with late end-stage rejection. All eleven patients with good or equivocal responses have functioning kidneys in a follow-up of 1-15 months (mean 7 months). Only one patient has had a subsequent acute rejection episode, which responded to a steroid pulse. No significant complications of anti-T12 therapy occurred.

Human renal allografts: Glomerular deposits of horse immunoglobulin G and nephritis following administration of antilymphocyte globulin

Abstract The administration of horse antilymphocyte globulin (ALG) containing glomerular basement membrane (GBM) cross-reactive antibody has the potential for inducing nephritis of the anti-GBM (linear) type. Similarly, a hostantihorse antibody response to the ALG may result in antigen-antibody complex (granular) nephritis. GBM cross-reactive antibody is more likely to be present in ALG derived from horses immunized with suspensions of lymph modes or thymus than with washed lymphoid cell suspensions, possibly because of the presence of other tissue antigens. However, ALG derived from some of our horses immunized with washed human thoracic duct lymphocytes also contained antibody cross-reactive with human GBM. Such antibody was found to be intermittently present in subsequent bleeds (ALG lots) following its demonstration in initial or early ALG lots. An ALG lot submitted for our evaluation of its possible GBM cross-reactivity was strongly positive but showed a marked reduction in cross-reactivity during extended storage at −20°C. Therefore, each lot of ALG should be tested for the presence of GBM cross-reactive antibody immediately after preparation. Of 58 renal allograft recipients treated intramuscularly with ALG and other immunosuppressants, allograft biopsies were taken for specific indications in 32. Examination of these biopsies for deposits of horse immunoglobulin G (IgG) showed that two contained linear deposits, suggesting that the cross-reactive antibody had not been completely absorbed locally following intramuscular administration. One of the latter two immunosuppressed recipients developed nephritis, probably a result of GBM cross-reactive antibody, from which he subsequently recovered. Although not all patients who received ALG containing GBM cross-reactive antibody develop clinically significant nephritis, until more data are available regarding the nephrotoxic effects of ALG, only lots found not to contain such antibody should be used clinically.

Rejected human renal allografts: recovery and characteristics of infiltrating cells and antibody.

Viable infiltrating host leukocytes have been isolated from 10 rejected human renal allografts, removed 1 to 67 months after transplantation. The cell populations have been identified by surface characteristics and their cytotoxic capacities were assessed. A heterogenous population of cells of host origin accumulated in the grafts, including T and B lymphocytes, Fc+ cells, and macrophages. Using a 51Cr release assay, specific cytotoxicity against donor alloantigens was determined. Cytotoxicity of the infiltrating cells was almost invariably greater than cytotoxicity mounted by recipient peripheral blood lymphocytes. Deletion studies confirmed previous work and suggested that T cells were primarily responsible for cytolysis in early acute rejection; non-T cells more often in late chronic rejection. Antibodies eluted from the grafts demonstrated both specific antidonor and nonspecific activity as well as cross-reacting anti-HLA activity. Allograft morphology was examined and cellular and humoral host responses were assessed. These studies emphasize the complexities of immune responses produced by the host against transplanted tissues.

Definition, genetics, and possible significance of a newly defined endothelial antigen in the rat

The purpose of the present experiments was to define a non-major-histocompatibility-complex (MHC) endothelial antigen system in the rat and to study the genetics of these antigens as well as their significance in renal transplantation. Several MHC-identical rat strain combinations underwent reciprocal inmunization using spleen and lymph node cells and complete Freunds adjuvant. In one combination (MAXX anti-BN) alloantibodies were found against antigens on peritubular and venous endothelium of the kidney from the immunizing strain as well as from two other strains. Preliminary results suggested that the endothelial antigen is present on monocytes but not on nonstimulated T and B lymphocytes. With kidneys from 7 MHC-congenic lines it was shown that the endothelial antigens are encoded outside the MHC-region. The antigen seems to be expressed as a dominant trait. In an F2 population of 32 animals, segregation of the endothelial antigen or antigens appeared to be independent of the MHC, AgF, and tubular basement membrane antigens—as well as the locus for albinism. Transplantation of MHC-identical but endothelial-antigen-incompatible kidneys into nonimmunized recipients did not provoke acute rejection. Pretransplant immunity against donor endothelial antigens was, however, associated with accelerated acute rejection. The rejection was donor-specific because third-party MHC-incompatible but endothelial-antigen-compatible kidneys were rejected like first-set grafts. This model shows that graft rejection in presensitized recipients of an MHC-identical kidney can be mediated through immunity against non-MHC antigens.

THE MONKEY SKIN GRAFT MODEL AS AN ASSAY OF HUMAN ANTILYMPHOCYTE GLOBULIN

SUMMARY Thirteen lots of horse antihuman lymphocyte globulin (ALG), produced using several different antigen sources and methods of preparation, were tested in the primate skin allograft assay system. Each ALG tested showed significant prolongation of skin allograft survival (range, 15-44+ days; average, 22.79 ± 8.93 days) compared to the control (9.95 ± 1.46 days). No antigen source, method of preparation, or route of administration produced consistently longer survival and none prevented the formation of specific antibody against the skin graft donors. I.v. administered ALG did not lead to the fixation of antiglomerular basement membrane (GBM) antibody as assessed by conventional immunofluorescent techniques and resulted in a lower incidence of antihorse IgG antibody production than that following administration by the s.c. route. One lot of ALG, however, caused fatal disseminated intravascular coagulation in four monkeys, only when administered i.v. A positive correlation between primate skin allograft survival and rosette inhibition (RI) titers was not demonstrated.

Hyperimmune F(ab′)2 antibody: Role in canine hyperacute renal allograft rejection☆

An attempt to obtain protection of the renal allograft in a sensitized recipient by ex vivo perfusion with F(ab′)2-modified antibody was unsuccessful. The major contributing factor to this failure appeared to be related to the species differences in IgG and their mode of degradation. The canine IgG molecule proved to be very hard to degrade to F (ab′)2 as tested by the loss of the lymphocytotoxic titer at the end of 20 hr of pepsin digestion.