In this study, the plant based biopolymeric fraction RLJ-NE-205 isolated from Picrorhiza kurroa were evaluated for its potential ability as an adjuvant effect on the immune responses to Ovalbumin (specific antigen) in mice. Immunization in Balb/C mice with variable doses of RLJ-NE-205 (10 – 80 g) with optimized dose of Ovalbumin (100 g) dissolved in phosphate buffered saline or containing alum (200 g) on Days 1 and 15. After two weeks of the challenging dose, OVA specific antibodies in serum, spleen cell proliferation assay, estimation of Th1 (IL-2/IFN-gamma) and Th2 (IL-4) cytokines in serum, CD3/CD4/CD8/CD19 surface markers of T and B cell, costimulatory molecules (CD80/CD86) in spleen cells and safety studies were observed. The results suggest that OVA mediated specific antibody levels (IgG, IgG1 and IgG2a) in serum were significantly enhanced by RLJ-NE-205 (20 g) containing 100 g OVA compared with OVA control group. Moreover, RLJ-NE-205 (20 g) containing 100 g OVA on IgG, IgG1, and IgG2a antibody responses to OVA in mice were more significant than those of alum. RLJ-NE-205 (20 g) significantly enhanced the OVA induced spleen cell proliferation and estimation of Th1 and Th2 cytokines in the OVA immunized mice. However, no significant differences were observed among the OVA group and OVA/alum group. At the dose of 100 g OVA containing 20 g RLJ-NE-205, there was a significant increase in the Th1 and Th2 cytokines in serum and CD3/CD4/CD8/CD19 surface markers and costimulatory molecules (CD80/CD86) in the spleen cell by flow cytometry were observed
