Immunostimulatory activity of Picrorhiza kurroa leaf extract.

A 50% ethanolic extract of Picrorhiza kurroa Royle ex Benth. (Scrophulariaceae) leaves (PKLE) was found to stimulate the cell-mediated and humoral components of the immune system as well as phagocytosis in experimental animals. PKLE elicited a dose-related increase in SRBC, induced 4 h (early) and 24 h (delayed) hypersensitivity reactions in mice and rats, and horse serum induced Arthus reaction in guinea pigs. It also enhanced the humoral immune responses in mice and rats and phagocytic function of the cells of the reticuloendothelial system in mice. PKLE exhibited no mitogenic activity but augmented the responsiveness of murine splenocytes to T cell mitogens phytohaemagglutinin (PHA) and concanavalin A (Con A) and B cell mitogen lipopolysaccharide (LPS E. coli).