Mitogenic Activity of a Water‐Soluble Adjuvant (Bu‐WSA) Obtained from Bacterionema matruchotii

Butanol‐extracted water‐soluble adjuvant (Bu‐WSA) obtained from Bacterionema matruchotii was cultured with peripheral blood mononuclear cells (PBM) in the presence of sub‐ and/or supra‐optimal mitogenic concentrations of concanavalin A (Con A). The addition of Bu‐WSA resulted in increased tritiated thymidine incorporation above that produced by Con A alone. Bu‐WSA by itself is not mitogenic for PBM and in fact produced a decrease in thymidine uptake compared to the control. We investigated the response of subpopulation(s) of PBM to Bu‐WSA, Con A and a mixture of Bu‐WSA and Con A. Separation of PBM into purified T cells, B cells and macrophages showed that cell‐cell cooperation of T cells with B cells or macrophages is necessary for the observed synergistic effect of Bu‐WSA with Con A. A marked increase in thymidine incorporation by the mixture of T and B cell populations occurred, while only a small amount of thymidine was incorporated when the B cell population was absent. Mitomycin treatment revealed that the response could be ascribed to the T‐cell response with a B‐cell helper effect. Moreover, Con A and Bu‐WSA appeared to act on the same T cell population. This model may provide unique information about the activation of human peripheral blood T cells compared with the activation of these cells by other mitogens.