Tonsillar and peripheral blood lymphocytes from 20 patients with tonsillitis were examined for production of Epstein-Barr virus (EBV) and antinuclear antibodies within 2 weeks after EBV transformation. All established lymphoblastoid cell lines (LCLs) contained more than 90% EBV nuclear antigen-positive cells. However, no LCLs produced biologically active virus. On the other hand, 10 (50%) out of 20 tonsillar LCLs and 4 (20%) out of 20 peripheral blood LCLs produced autoantibodies. These results showed that there are differences in an EBV-induced lymphocyte autoantibody response between tonsillar lymphocytes and peripheral blood lymphocytes.