Effect of Ocimum sanctum extract on the induction of IFN-γ and IL-10 cytokines and their m-RNA expression

Ocimum sanctum (family -Labiatae) is the most sacred plant in India. Since ancient time it has been used by Ayurvedic practioners and laypersons for many health ailments and it has both medicinal and spiritual significance in Ayurveda. The effect of oral treatment with aqueous leaves extract of Ocimum sanctum on immune responses, concanavalin-A (ConA) stimulated spleen cell proliferation and cytokines (IFN-γ & IL-10) were analyzed. The wistar albino rats' model was used during the study. Feeding of Ocimum sanctum enhanced both types of immune responses: antibody titre against Salmonella Typhimurium ‘0’ antigen and cell mediated immune response using DNCB as an antigen. Daily uptake of 250mg/kg for 20 days by rats did not show any sign of toxicity. Spleen cells harvested from the treated rats in the presence of ConA showed increased proliferation. Wi star albino rats' spleen cells treated in vitro with different concentrations (25–500μg/ml) of Ocimum sanctum in presence of ConA also exhibited increase in their proliferation. A significant increase in IFN-γ production was also observed from the mitogen stimulated splenocytes obtained from treated rats while the IL-10 production was not significantly affected. But in vitro experiments the IL-10 production was significantly increased and the IFN-γ production was not markedly enhanced. Enhanced expression of IFN-γ m-RNA in spleen cells of rats after oral administration of Ocimum sanctum extract was also evaluated by the RT-PCR analysis and it demonstrated the increase in production of IFN-γ where as IL-10 m-RNA expression was not with a significant change.