Effect of Nocardia rubra cell wall skeleton on murine interferon production in vitro.

Nocardia rubra cell wall skeleton (N-CWS) induced alpha- plus beta-interferons (IFN-alpha/beta) in resident peritoneal cells and bone marrow cells from normal mice. N-CWS also induced IFN-alpha/beta and IFN-gamma in the cultures of thioglycollate-elicited peritoneal cells. When induced with N-CWS, the mixed cultures of thioglycollate-elicited macrophages and spleen cells produced high titered IFN-gamma. Both macrophages and lymphocytes present in spleen cells (non-T, non-B, asialo-GM1-positive) were essential for the production. Immunofluorescence staining with anti-IFN-gamma antiserum showed the presence of IFN-gamma in lymphocytes but not in macrophages, suggesting that lymphocytes were producer cells and macrophages were accessory cells. Because IFN-gamma is an important lymphokine in immune response, the ability of N-CWS to stimulate IFN-gamma production may account for a significant portion of the antitumor activity of this agent.