Adjuvant effects of salidroside from Rhodiola rosea L. on the immune responses to ovalbumin in mice

Salidroside, a major component of Rhodiola rosea L., was evaluated for its adjuvant effects on the immune responses in mice by ovalbumin (OVA) stimulation. BALB/c mice were immunized subcutaneously with OVA 100 mu g or OVA 100 mu g dissolved in saline containing alum (100 mu g) or salidroside (12.5, 25, or 50 mu g) on Days 1 and 15. Two weeks later (Day 28), blood samples were collected to analyze OVA-specific IgG, IgG1, and IgG2b antibodies. Meanwhile, splenocytes were harvested to assess lymphocyte proliferation, cytokines (IL-2, IL-4, and IFN-gamma) production, and CD4(+), CD8(+) lymphocyte subsets. The results indicated that co-administration of salidroside with OVA significantly enhanced the ConA-, LPS-, and OVA-induced splenocyte proliferation, produced more IL-2, IL-4, IFN-gamma, and IgG, IgG1, and IgG2b antibody levels, and increased the percentage of CD4(+), CD8(+) lymphocyte subsets than OVA alone. Thus, salidroside possess immunological adjuvant activity by regulating humoral and cellular immune responses in mice.