Participation of Interleukins in Synergistic Effect of Bu‐WSA on Concanavalin A‐Induced DNA Synthesis in Mouse Splenic Lymphocytes

Abstract

Butanol‐extracted water‐soluble adjuvant (Bu‐WSA) obtained from Bacterionema matruchotti was mitogenic to murine splenic B lymphocytes, but not T lymphocytes. When murine splenic cells were cultured in the presence of Bu‐WSA and concanavalin A (Con A) together. [3H|thymidine uptake of the culture cells synergically increased. The mechanism of the synergy of Con A and Bu‐WSA and the participation of interleukin (IL) 1 and 2 in the synergy were studied. The proliferation cells in the synergy were I yt‐1− 23− lymphocytes.’la‐positive accessory cells were required for the response. When separated cell populations and Marbrook‐type culture vessels were used, a mixed cell population of T lymphocytes and B lymphocytes or macrophages (Mφ) produced some active factor(s) after co‐stimulation by Con A and Bu‐WSA, and the factors enhanced DNA synthesis of another Con A‐activatcd T lymphocyte population. Supernatants obtained from the spleen cell cultures or the mixed cell cultures with T lymphocytes and Mφ in the presence of Con A and Bu‐WSA contained greater amounts of IL‐1 and IL‐2 than those from cultures containing Con A or Bu‐WSA alone. An addition of exogenous IL‐1 or IL‐2 to spleen cell cultures with Con A resulted in a proliferative response like that obtained through co‐stimulation by Con A and Bu‐WSA. These results suggest that the synergistic effect of Con A and Bu‐WSA on the proliferative response in murine splenic cells is sustained by the enhancement of production of these T‐lymphocyte growth factors.