title: Differential effects of transferrin receptor blockade on the cellular mechanisms involved in graft rejection.
abstract: Since transferrin receptor (TfR) appears on activated T cells following the interaction of the antigen-major histocompatibility complex (MHC) with the T cell receptor (TCR) and the appearance of interleukin (IL)-2R, we therefore hypothesize that in vivo blockade of TfR prolongs allograft survival by altering the cellular mechanisms involved in graft rejection. Previous results in our laboratory have demonstrated that anti-TfR monoclonal antibody (mAb) at 100 microg on days 0 and 1 of transplantation significantly prolonged allograft survival to 25.7 +/- 0.9 days in a murine heterotopic, nonvascularized cardiac allograft model. In the current studies, administration of anti-TfR mAb at the time of maximal TfR expression, on days 2 and 3 post-transplantation, failed to prolong allograft survival (13.0 +/- 0.0 days) compared to the isotype controls (10.5 +/- 0.5 and 10.7 +/- 0.4 days) (p < 0.01, Wilcoxon rank sum). A 4-day course of anti-TfR mAb significantly prolonged allograft survival compared to the isotype controls, but was no more effective than a 2-day course of the mAb. Anti-TfR mAb suppressed the mixed lymphocyte response to donor-specific and third-party alloantigen by 78.7% (p < 0.05) and 80.8% (p < 0.05), respectively, while stimulating the CTL response to donor-specific (16.3%, p < 0.05) and third party (49.3%, p < 0.01) alloantigen. Anti-TfR mAb suppressed IL-15 and increased IL-4 intragraft mRNA expression when compared to the isotype controls. Examination of cell surface receptors important during T cell activation revealed alterations in expression following anti-TfR mAb treatment. Anti-TfR mAb is an effective immunosuppressant prolonging allograft survival by altering cell-mediated immune responses and the intragraft cytokine micro-environment.
authors.affiliation: Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, USA.
authors.forename: A L
authors.initials: AL
authors.lastname: Bayer
authors.forename: P
authors.initials: P
authors.lastname: Baliga
authors.forename: J E
authors.initials: JE
authors.lastname: Woodward
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D016207:Cytokines / Q000235:genetics; D005260:Female; D006084:Graft Rejection / Q000209:etiology* / Q000276:immunology / Q000378:metabolism; D016027:Heart Transplantation / Q000276:immunology; D007165:Immunosuppression Therapy; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011990:Receptors, Transferrin / Q000037:antagonists & inhibitors* / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014184:Transplantation, Homologous
chemical_list: D000911:Antibodies, Monoclonal; D016207:Cytokines; D012333:RNA, Messenger; D011990:Receptors, Transferrin