Autoantibody against B lymphocytes.

The sera of 20 out of 99 (20%) normal males and females were shown to have antibodies that kill their own B lymphocytes. The sera were specifically cytotoxic to B lymphocytes and not T lymphocytes. Allogeneic B lymphocytes were also killed by these autocytotoxins. Maximum killing of B lymphocytes occurred when the incubation temperature in serum was 5 degrees C and complement incubation temperature was 20 degrees C. Under these cold conditions, some sera reacted up to a dilution of 1/16. These results suggest that positive B-lymphocyte crossmatches found in kidney transplantation do not detect alloantibodies. Since the B-cell autoantibodies tend to appear at the time of immunisation, their role as autoregulators of the antibody response is an intriguing possibility.