A NEW MURINE LYMPHOCYTOTOXIC MONOCLONAL-ANTIBODY RECOGNIZING HLA-A2, HLA-A28 AND HLA-A9

Monoclonal antibodies recognizing polymorphic as well as monomorphic e pitopes on HLA antigens are important tools for understanding the immu nobiology of HLA molecules. We immunized BALB/c mice with a HLA-A2 tra nsfectant and screened for hybridomas which reacted with a HLA-A2 tran sfectant but not with a HLA-B75 transfectant. After subcloning by limi ting dilution four times, a hybridoma secreting a monoclonal antibody (mAb) (IgG 2a, kappa) designated 1-145 was established. 1-145 reacted with Epstein-Barr virus transformed B lymphoblastoid cell lines (B cel l lines) which expressed HLA-A2, -A28, -A23 and -A24. The titer of 1-1 45 in culture supernatant against HLA-A2 and -A28 antigens was similar and the titer against HLA-A23 was lower. 1-145 reacted with cells exp ressing HLA-A24 but the titer against HLA-A24 antigens was even lower than that againt HLA-A23 antigens. The HLA-A24 antigens on the periphe ral blood lymphocytes were not detected by 1-145 possibly due to the l ower expression compared to the B cell lines. These differences of the titers were reflected to microlymphocytotoxicity assay in which 1-145 culture supernatant lysed all PBLs expressing HLA-A2, -A28 and -A23 b ut did not lyse PBLs expressing HLA-A24. Published deduced amino acid sequence data of HLA class I molecules indicate that Lys in position 1 27 may be critical for 1-145 binding.