PUBLIC B CELL ALLOANTIGEN DETERMINANTS (Ia) AND ACTIVE ENHANCEMENT OF RENAL ALLOGRAFTS IN THE RAT

Abstract

Experimental renal transplantation in the rat model has established that immunity to certain donor B cell Ia antigenic determinants is associated with enhanced graft survival. Preimmunization of LEW [rat] hosts with BUF [rat] lymphoid cells produced a significant prolongation (P < 0.005 by log rank analysis) of survival of renal allografts taken from a 3rd party (LEW .times. BN)F1. Serological analysis demonstrated that BN and BUF share an MHC[major histocompatibility complex]-encoded public Ia specificity, expressed on B cells, which was called Ia.15. Hyperimmune sera directed at this specificity are cytotoxic to 20 .+-. 3% of lymph node cells, significantly inhibit the formation of EA [ox erythrocyte, antibody] rosettes by Fc receptor-bearing cells (EAI), and inhibit mixed lymphocyte reaction (MLR) by 50-60% when directed at the stimulatory but not when directed at the responder strain cells. A study of a large number of hyperimmune sera raised between inbred rat strains, by EAI and complement-dependent cytotoxicity (CDC) vs. B cells, revealed broad patterns of cross-reactivity, suggesting that public Ia determinants are complex and highly immunogenic. Immunity restricted to a public Ia antigen plays a role in allograft enhancement.