Adjuvant effect of aqueous extract of Rhodiola imbricata rhizome on the immune responses to tetanus toxoid and ovalbumin in rats.

In the present study we have evaluated the immunopotentiating activity of Rhodiola aqueous extract (RAE) in rats. The efficacy of RAE was determined by using strong antigen tetanus toxoid (TT) and weak antigen Ovalbumin (OVA). The dynamic changes in humoral and cell-mediated immune response were measured. The results indicated that the TT specific immunoglobulin levels were significantly enhanced by RAE and were at par with complete Freund's adjuvant (CFA). The level of OVA induced antibody response was also enhanced by RAE. It was observed that TT and OVA in combination with CFA or RAE could evoke a significant delayed type hypersensitivity (DTH) response, confirming its potential to generate strong cell-mediated immunity (CMI). The anti-inflammatory or immunosuppressive effect of RAE was evaluated in adjuvant-induced arthritis model (AIA). RAE could not suppress the swelling response. Therefore, this study suggests that RAE has adjuvant/immunopotentiating activity in terms of humoral as well as cell-mediated immune response against strong antigen like TT and weak antigen like OVA.