The influence of mitogen costimulation on the human lymphocyte blastogenic response to Actinomyces viscosus ultrasonicates.

Human peripheral blood lymphocytes were cultured for 48 hr in the presence of an ultrasonicate supernatant fraction of A~~tinonr.vces r~i~c~os~,s (AV-SUP). After washing to remove AV-SUP, the lymphocytes were cultured in the presence of concanavalin A or pokeweed mitogen for an additional 72 hr. Measurement of [,‘H]thymidine incorporation into DNA indicated that AV-SUP preculture resulted in an amplified or elevated response to mitogen stimulation compared to mock precultured cells and unstimulated controls. Addition of fresh cells prior to mitogen activation resulted in an additional incremental increase over controls. The modulated cell appeared to reside in the AVSUP precultured population, since treatment of these cells with mitomycin C prior to coculture with fresh cells totally abrogated the effect. However, mitomycin C treatment of the fresh population had no effect on mitogen-induced amplification. Results of these experiments suggest that mitogen stimulation activates a helper function which allows the precultured cells to respond to AV-SUP stimulation.