EVIDENCE FOR A ROLE OF Ir-ASSOCIATED ALLOANTIGENS IN MIXED LYMPHOCYTE CULTURE STIMULATION

A variety of / r -associa ted routine lymphoid cell surface antigens (Ia antigens), at least some of which are preferentially expressed on B cells, have recently been reported (1-3). They are determined by genetic information mapping in the Ir region of the mouse major histocompatibili ty complex (MHC). In this laboratory one such Ia antigen has been demonstrated on B cells of an H-2a,H-2 b recombinant congenic strain (B10.A(2R)) (2). No corresponding antigen has yet been demonstrated on B10.A(4R) cells. I t has therefore been suggested that this Ia alloantigen of B10.A(2R) mice may be responsible for the "one-way" mixed lymphocyte culture (MLC) reaction between these two recombinant strains (2, 4). In this paper we further assess the possible role of Ia alloantigens in the MLC.