EXPRESSION OF MAJOR HISTOCOMPATIBILITY COMPLEX IN MOUSE PERITONEAL-MACROPHAGES INCREASINGLY DEPENDS ON PLASMA-CORTICOSTERONE LEVELS - STIMULATION BY ACONITINE

Influence of aconite extract and a main component of aconite, aconitin e were investigated on the plasma corticosterone level for the express ion of major histocompatibility complex class II (Ia antigen) of macro phage. In peritoneal macrophage exposed to corticosterone (2.9-87 mu M ) in vitro the interferon (IFN)-gamma (0.1 unit/ml-induced la antigen expression was inhibited in a dose-dependent manner, Ia antigen expres sion in macrophages harvested from the corticosterone (1.25 mg/mouse/d , i.m., 4d)-excessive mice and aconitine (3 mu g/kg, i.p., 7 d)-treate d mice was significantly stimulated, whereas that of adrenalectomized (7d) mice was inhibited. In macrophage exposed to aconitine up to 46.5 mu M in culture Ia antigen expression was not affected. Administratio n of aconite extract (3 mg/kg, i.p., 7d) and aconitine (3 mu g/kg, i.p ., 7d) increased plasma corticosterone levels, These results demonstra te that high levels of corticosterone increase the macrophage response to IFN-gamma on Ia antigen expression and that low levels of corticos terone decrease it, Aconite extract and aconitine stimulate the respon se to IFN-gamma-activated expression of Ia antigen by macrophages whic h is caused by increasing the plasma corticosterone level.