Responses of guinea-pig lymphocytes to mitogens, an antigen, and mixed leucocyte culture in media with and without mercaptoethanol and foetal calf serum.

The ability of guinea-pig spleen and lymph node cells to undergo a proliferative response in vitro in the presence of mitogens (concanavalin A and lipopolysaccharide), a specific antigen (oxidized ferredoxin), and allogeneic cells was assessed under a variety of conditions. Time and dose dependency of the responses was measured in RPMI 1640, RPMI 1640 plus mercaptoethanol (ME), RPMI 1640 plus foetal calf serum (FCS), and RPMI 1640 with ME and FCS. Mitogen responses were also measured after treatment of the cells with sheep antiguinea pig immunoglobulin (SaGPIg) and complement (C') or after passage through nylon wool columns. Lipopolysaccharide (LPS) stimulated the cells under all media conditions over a wide range of concentrations but over a narrow time period. Nylon wool treatment of the cells eliminated the LPS response while SaGPIg and C' reduced it. Concanavalin A (con A) stimulated the cells under all test conditions and demonstrated a dose-time interrelationship in terms of maximum response. Pre-treatment of cells with SaGPIg and C' enhanced the response to con A while nylon wool fractionation diminished it somewhat. Only lymph node cells responded in vitro to oxidized ferredoxin (OFd). In serum-free media the OFd responses were maximal at 48 hours whereas in media containing FCS proliferative responses were supported for a prolonged period and appeared to be bimodal. Except for an early response with RPMI 1640 and ME, only media containing FCS supported stimulation in the mixed leucocyte culture.