QUANTITATION OF HLA CLASS-II ANTIGENS ON B-CELL LINES

By quantitation of elutable immunoglobulin G in a recently described E LISA, the number of HLA class I and II molecules on B-cell lines was d etermined using monomorphic monoclonal antibodies. An average number o f 183 000 binding sites per cell for HLA class I-, 99000 for HLA-DR-, 63000 for DQ- and 42000 for DP-specific monoclonal antibodies were det ermined. The small amount of HLA class II molecules can in part explai n the difficulties observed in HLA class II typing or in detection of class II antibodies using the lymphocytotoxicity text.