A cross-reactive idiotype on anti-DNA and lymphocytotoxic antibodies.

The possibility that shared idiotypes may be present on antibodies of different specificities was explored using sera from 13 patients with systemic lupus erythematosus. Eleven sera had anti-DNA and seven carried the 16/6 idiotype (ID). Two of the sera with 16/6 ID also had lymphocytotoxic antibodies, the activity of which was blocked by antibody to the 16/6 ID. Our studies reveal that 16/6 ID is present on two antibodies with different binding specificities.