Inhibition of immediate-type allergic reactions by Prunella vulgaris in a murine model.

We studied the effect of aqueous extract of Prunella vulgaris (Labiatae) (PVAE) on immediate-type allergic reactions. PVAE (0.005 to 1 g/kg) dose-dependently inhibited systemic anaphylactic shock induced by compound 48/ 80 in rats. When PVAE was given as pretreatment, at concentrations ranging from 0.005 to 1 g/kg, the serum histamine levels induced by compound 48/ 80 were reduced in a dose-dependent manner. PVAE (0.001 to 1 g/kg) inhibited the passive cutaneous anaphylaxis activated by anti-dinitrophenyl (DNP) IgE antibody dose dependently. PVAE also inhibited the histamine release induced by compound 48/80 or anti-DNP IgE from the rat peritoneal mast cells (RPMC). The level of cyclic AMP in RPMC, when PVAE was added, significantly increased, compared with that of normal control. Moreover, PVAE (0.01 and 0.1 mg/ml) had a significant inhibitory effect on anti-DNP IgE-mediated tumor necrosis factor-alpha production from RPMC. These results indicate that PVAE inhibits immediate-type allergic reactions in rats.