ACTIVATION OF HUMAN B-LYMPHOCYTES .3. CONCANAVALIN A-INDUCED GENERATION OF SUPPRESSOR CELLS OF PLAQUE-FORMING CELL RESPONSE OF NORMAL HUMAN B-LYMPHOCYTES

Abstract

Con A[concanavalin A]-induced suppression of the direct PFC [plaque-forming cell] response to polyclonal stimulation in human B [bone marrow-derived] cells was described. Two types of experiments were presented. Con A was added directly to PWM[pokeweed mitogen]-stimulated PB [peripheral blood] or tonsil cells resulting in a dose-dependent suppression of the PFC response, with maximal suppression occurring at a Con A concentration of 10 .mu.g/ml. This suppression is completely removed by the simultaneous addition of .alpha.MM [methyl-.alpha.-D-mannopyranoside]to the cultures. Con A stimulation of tonsil or PB lymphocytes generated a population of cells which when added to autologous lymphocyte cultures indiced a marked and reproducible suppression of the PFC response. The generation of suppressor cells was dependent on cell division and was blocked by .alpha.MM. Once generated the process of suppression was independent of the presence of Con A itself and was mediated by an activated lymphocyte population. These studies demonstrated a simple and reproducible model for the generation of a population of suppressor cells capable of inhibiting the direct PFC response to PWM-induced polyclonal activation of normal human B lymphocytes.