ACTIVATION OF HUMAN B-LYMPHOCYTES .5. KINETICS AND MECHANISMS OF SUPPRESSION OF PLAQUE-FORMING CELL RESPONSES BY CONCANAVALIN A GENERATED SUPPRESSOR CELLS

Abstract

The kinetics and mechanisms of suppression of the PWM[pokeweed mitogen]-induced PFC [plaque-forming cell] response of human PB [peripheral blood] lymphocytes by Con A[concanavalin A]-activated suppressor cells were investigated. It was necessary that Con A suppressor cells be present early in the process of activation of human B [bone marrow-derived] cells toward antibody synthesis, but maximal suppression of the PFC response occurred later in the culture period. Con A-activated cells, although suppressing the PFC response to PWM greater than 90% of control, did not significantly suppress the blastogenic response to PWM after 3 or 5 days in culture. After 3 days in culture, background 3H-thymidine incorporation as well as 3H-thymidine incorporation to PWM stimulation was increased when Con A suppressor cells are added to fresh autologous peripheral blood lymphocytes. This increased blastogenic response after 3 days most likely represented an autologous mixed lymphocyte reaction (MLR) of Con A suppressor cells against fresh autologous non-T [thymus-derived] cells. The induction of autoreactive cells may be 1 of several modes of suppression of PFC responses by Con A activated suppressor cells.