Staphylococcal Enterotoxin A Induced Interferon (IFN)-γ Production in Spleen Cells from BCG-Immunized Mice: The IFN Production is Dependent on Leukotriene C 4 but not Dependent on Interleukin 2

Abstract

In our previous paper, we showed that IFN was induced in sera by injection of staphylococcal enterotoxin A (SEA) in Bacillus Calmette-Guérin (BCG) immunized C57BLl6 (B6) mice. In analyzing the phenomenon in vitro, we showed that SEA induced IFN-γ in the supernatant of the spleen cell culture from BCG immunized B6 mice and that leukotriene C 4 (LTC 4) from BCG activated macrophages in the spleen was involved in the IFN production from Ly 1 + T cells. On the other hand, interleukin-2 (IL-2) has reported to play an important role in the regulation of synthesis of IFN-γ by T cells. In the present study, we examined whether IL-2 is involved in SEA-induced IFN production. The result showed that the SEA-induced IFN-γ production was observed in spite of suppression of SEA-induced IL-2 production in spleen cells from BCG-immunized B6 mice. On the contrary, the depressed IFN production was observed in spite of high SEA-induced IL-2 production in spleen cells from their control mice. On the other hand, LTC 4 production was 8 times higher in spleen cells from BCG-immunized B6 mice, high producer of SEAinduced IFN, than in that from BCG-immunized C3H mice, the low producer. We also observed that the IFN and the LTC 4 production of spleen cells from BCGimmunized B6 mice was suppressed in the presence of caffeic acid and nordihydroguaiaretic acid, non-specific lip oxygenase inhibitors, and that LTC 4 augmented the IFN production of normal B6 mouse spleen cells in the presence of 2-mercaptoethanol. Therefore, involvement of LTC 4 rather than of IL-2 was supported in our experimental system.