Immunoregulatory factors controlling terminal differentiation of malignant B-lymphocytes

B-lymphocytes of patients with chronic lymphocytic leukemia differentiate in vitro towards plasma cells upon activation with Pokeweed mitogen (PWM) and Cowan. The level of response is much lower than that of normal cells and so is the helper T-cell function. However, concanavalin A-activated suppressor T-cell function of Ig synthesis is normal. Malignant B-cells have a normal capacity to stimulate Ig synthesis in the mixed lymphocyte cultures, but they respond poorly to an allogeneic stimulus. Thymosin (TFX) causes a marked enhancement of PWM-driven differentiation of malignant B-cells.