Expression of Major Histocompatibility Complex in Mouse Peritoneal Macrophages Increasingly Depends on Plasma Corticosterone Levels : Stimulation by Aconitine

Abstract

Influence of aconite extract and a main component of aconite, aconitine were investigated on the plasma corticosterone level for the expression of major histocompatibility complex class II (Ia antigen) of macrophage. In peritoneal macrophage exposed to corticosterone (2.9-87 μM) in vitro the interferon (IFN)-γ (0.1 unit/ml)-induced Ia antigen expression was inhibited in a dose-dependent manner. Ia antigen expression in macrophages harvested from the corticosterone (1.25 mg/mouse/d, i.m., 4d)-excessive mice and aconitine (3 μg/kg, i.p., 7d)-treated mice was significantly stimulated, whereas that of adrenalectomized (7d) mice was inhibited. In macrophage exposed to aconitine up to 46.5 μM in culture Ia antigen expression was not affected. Administration of aconite extract (3mg/kg, i.p., 7d) and aconitine (3 μg/kg, i.p., 7d) increased plasma corticosterone levels. These results demonstrate that high levels of corticosterone increase the macrophage response to IFN-γ on Ia antigen expression and that low levels of corticosterone decrease it. Aconite extract and aconitine stimulate the response to IFN-γ-activated expression of Ia antigen by macrophages which is caused by increasing the plasma corticosterone level.