B lymphocyte function in B cell chronic lymphocytic leukaemia.

B-enriched lymphocyte populations from patients with chronic lymphocytic leukaemia (CLL) were compared to B-enriched lymphocyte populations from normal age-matched controls for their ability to stimulate a proliferative response and to generate cytotoxic cells in allogeneic mixed lymphocyte cultures (MLC). The proliferative responses of MLCs were less than normal when the stimulating cells originated from B cells of patients with CLL. The degree of stimulation provided by the B cells from the patients with CLL inversely correlated with the peripheral white cell count. Lymphocytes from patients providing a poor stimulatory signal in the MLC tended to have less "Ia-like" antigen than lymphocytes giving a moderate level of stimulation. B lymphocytes from patients with CLL which stimulated poorly in the MLC also failed to generate specific cytotoxic cells even when provided with a normal proliferative trigger. These data suggest that B lymphocytes from cases of CLL with markedly elevated leucocyte counts may have a diminished concentration of both "Ia-like" and serum defined antigens.