Mitogenic stimulation of malignant B cells. Chronic lymphocytic leukaemia: relationship between stimulation and surface phenotype.

Peripheral blood lymphocytes (PBL) from 14 patients with chronic lymphocytic leukaemia (CLL) were stimulated with pokeweed mitogen (PWM), formalinized Staphylococcus aureus (Sta) and a combination of both mitogens. The leukaemic B cells were characterized by rosetting techniques (using mouse erythrocytes and complement coated erythrocytes) and immunofluorescence for membrane bound immunoglobulin (mIg). No clear correlation between phenotype and the reactivity with PWM could be found. Results of stimulation with Sta however, indicate that lymphocytes carrying membrane bound IgM (mIgM) and IgD (mIgD) and the receptor of the third complement component (C3R) can be induced to differentiate into immunoglobulin (Ig) containing cells. Addition of PWM to these cultures often enhanced this response. Some leukaemic B cells are able to differentiate after challenge with the appropriate stimulus.