Studies on Thermophile Products. XI. Biological Effect of Antigen Presenting Inhibitor, Isofatty Acid-Containing Phosphatidylethanolamine, on Mouse Macrophages

抄録

A new fraction, Fr. 8-A, which consists of a phosphatidylethanolamine with C_{14 : 0}-C_{18 : 0} isofatty acids was obtained from Bacillus stearothermophilus UBT8038. The fraction inhibited major histocompatibility complex class II (Ia) antigen expression and antigen presentation on mouse macrophages. The effect of Fr. 8-A on macrophage functions related to antigen presentation was investigated. Fr. 8-A increased arachidonate release, prostaglandin (PG) E₂ release and nitrite production from peritoneal macrophages. It increased further the levels of PGE₂, nitrite and tumor necrosis factor in the culture supernatant of the macrophages induced by the supernatant from concanavalin A-stimulated spleen cell cultures. Fr. 8-A augmented the activity of peritoneal macrophages to suppress Con A-stimulated T cell proliferation. Addition of either indomethacin or N^G-methyl-L-arginine had no effect on the augmentation of suppressor macrophage activity or the inhibition of antigen presentation by Fr. 8-A, while simultaneous addition of both inhibitors abrogated the effect of the fraction. These results indicate that Fr. 8-A inhibits Ia expression and antigen presentation, and augments suppressor macrophage activity at least partly via the activation of both cyclooxygenase and nitric oxide synthase pathways.