Lymphocyte activation with release of soluble mediators induced by Thermoactinomyces vulgaris in vitro

Murine spleen lymphocytes stimulated in vitro with a hypersensitivity pneumonitis-associated bacterium, Thermoactinomyces vulgaris, were found to secrete interleukin-2 up to 7 days after mitomycin C blockade. They exerted helper effect in secondary mitogen or antigen-induced lymphocyte proliferation. Cyclosporin A, an inhibitor of interleukin-2 synthesis, caused a complete abrogation of the helper effect, suggesting that the effect was mainly due to interleukin-2. Indomethacin, an inhibitor of prostaglandin synthesis, enhanced the helper effect in some inbred strains of mice, indicating prostaglandin-dependent downregulation. The strain variation in the prostaglandin-induced downregulation was not H-2 linked.