Immune mechanisms in organ allograft rejection. VI. Delayed-type hypersensitivity and lymphotoxin in experimental renal allograft rejection.
The cellular requirements for renal allograft rejection have been reassessed in a rat adoptive transfer model, preceding studies having shown that transplanted kidneys may be rejected in the absence of cytotoxic T cells or specific antibody. Unilaterally nephrectomized, sublethally irradiated (780 rads) LEW recipients of renal allografts from irradiated WF donors, were selectively reconstituted with spleen cells from sensitized syngeneic donors and subjected to delayed nephrectomy of the residual native kidney 3 days posttransplantation. In some experiments the reconstituting inocula were depleted of SIg+ cells (anti-Ig column) or additionally depleted of cytotoxic T cells and their precursors reactive with monoclonal OX8 (rosette depletion). Depleting the reconstituting inocula of SIg+ cells as well as cells reactive with monoclonal OX8 failed (n = 4) to alter the tempo of rejection, as demonstrated by a mean serum creatinine +/- SD on day 8 of 5.4 +/- 3.8 vs. 6.4 +/- 4.2 in recipients (n = 8) reconstituted with unfractionated inocula. These data support a link between DTH and graft rejection, so additional studies were performed to characterize rat lymphotoxin (LT), one of the potential mediators of DTH-induced tissue injury, and to demonstrate the presence of LT in rejecting rat renal allografts. Rat LT, generated in vitro by stimulating spleen cells from specifically sensitized rats with keyhole limpet hemocyanin (100 micrograms m/ml), was shown on gel filtration to have an MW of approximately 50,000. In-vitro-generated rat LT was shown to be heat stable (70 degrees C for 15 min) and soluble in 40% (NH4)2SO4. Rat LT eluted as a single peak on DEAE anion exchange chromatography (0-0.15 M, NaCl osmotic gradient), supporting the existence of but a single molecular form. LT was isolated from rejecting renal allografts on day 6 after renal transplant but undetected (less than 1 unit) in residual native kidneys. This study, therefore, provides substantial support for a link between DTH and renal allograft rejection. Lymphotoxin, one of the potential mediators of tissue injury in this model system, has been partially characterized and demonstrated to be present in rejecting rat renal allografts.
D000818:Animals; D006084:Graft Rejection; D006968:Hypersensitivity, Delayed; D007116:Immunization, Passive; D066298:In Vitro Techniques; D007668:Kidney / Q000276:immunology; D016030:Kidney Transplantation; D008212:Lymphocyte Depletion; D008233:Lymphotoxin-alpha / Q000096:biosynthesis / Q000302:isolation & purification; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011947:Receptors, Antigen, B-Cell; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014184:Transplantation, Homologous
D008233:Lymphotoxin-alpha; D011947:Receptors, Antigen, B-Cell