Abstract
A mouse monoclonal antibody of IgM class (TÜ165) was produced using Epstein‐Barr virus (EBV)‐infected mutant cells derived from the human BJAB‐B95.8.6 cell line as immunogen. Binding studies with several HLA deletion mutant cell lines indicated that TÜ165 recognized the HLA‐B35 molecule. In a panel of 89 EBV‐transformed lymphoblastoid cell lines, all HLA‐B35+ cells (n = 24) reacted with TÜ165 while all but two HLA‐B35^−^ lines (n = 65) were unreactive (r = 0.95). Surprisingly, peripheral blood lymphocytes of HLA‐B35+ donors were unreactive; however, strong enhancement of TÜ165 recognition was observed with B cells of one of these individuals after transformation with EBV (B95.8 strain). Transfection of both HLA‐B35 and human ß‐microglobulin genomic DNA into mouse P815 cells led to high expression of HLA‐B molecules; yet, expression of the TÜ165 epitope was not observed. Furthermore, the EBV‐negative cell line BJAB as well as the EBV‐infected (P3HR1 strain) line BJAB‐HR1K were only weakly reactive, whereas the BJAB‐B95.8 cell line was strongly positive. These results indicate that EBV‐encoded or ‐controlled peptide(s) must be bound by HLA‐B35 antigens to create the epitope which allows efficient binding of TÜ165.