PEPTIDE DEPENDENCE OF MAJOR HISTOCOMPATIBILITY COMPLEX CLASS-II SPECIFIC ALLOREACTIVE RESPONSES

Splenic cells from transgenic mice, in which a single peptide is compl exed to all major histocompatibility complex (MHC) class II molecules, are found to be incapable of triggering primary allogeneic mixed lymp hocyte/leucocyte reactions (MLR) when co-cultured with lymphocytes fro m MHC class II congenic mouse strains. In addition, a single HLA-DR-bl ocking peptide can completely abrogate the capacity of splenocytes fro m chimeric HLA-DR/H2-E transgenic mice to stimulate primary MLR of T c ells from wild-type mice. These results indicate that the primary allo reactive response is directed against a multitude of peptides presente d by allogeneic MHC molecules.