Lymphocyte transformation induced by autologous cells. XVI: Distinctive role of discrete regions of class I MHC antigens in the autologous mixed leucocyte reaction.

The role of Class I major histocompatibility complex (MHC) molecules in the autologous (AMLR) and allogeneic mixed lymphocyte reactions was investigated by using monoclonal antibodies (MoAb) directed to polymorphic MHC determinants. The AMLR from subjects with the HLA-A2 phenotype was consistently inhibited by the anti-HLA-A2 MoAb, CR11-351, and the inhibition was dose-dependent and complete even at low antibody concentrations. The allogeneic MLR was inhibited by CR11-351 less than 30% when HLA-A2-bearing cells were used either as stimulator or responder cells. Addition of interleukins 1 and/or 2 to the AMLR in the presence of the inhibiting MoAbs did not restore the proliferative response. These studies suggest that Class I MHC polymorphic determinants, or closely related structures, participate in the induction of the AMLR.