Interactions of Thermoactinomyces vulgaris and mouse alveolar macrophages. Loss of mitogenic activity and release of suppressive prostaglandins and interleukin 1

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.

Immunomodulating properties of lymphocytes activated by farmer's lung associated bacterium Thermoactinomyces vulgaris in vitro

Thermoactinomyces vulgaris, one of the aetiological agents of farmer's lung, was analysed for its ability to activate non-immune spleen lymphocytes from 10- to 14- week-old mice. The lymphocytes were found to exert both enhancing and suppressing signals after activation, depending on the secondary stimulation used. The enhancing effect is due to interleukin-2 secreted mainly by L3T4+ lymphocytes. The suppressive action is associated with Lyt2+ lymphocytes, which are probably activated by prostaglandins or histamine; but the suppression inducer action of L3T4+ lymphocytes may also be important. Genetic regulation, independent of H-2K and D, was also detected between different inbred strains of mice in response to T. vulgaris. The genetic regulation appeared associated with the different responsiveness of Lyt-2 positive lymphocytes between different strains. These results emphasize the importance of nonspecific activation in hypersensitivity disorders induced by microbiol antigens.