Haemolytic activities and adjuvant effect of Bupleurum chinense saponins on the immune responses to ovalbumin in mice

In this study, the haemolytic activities of Bupleurum chinense saponins (BCS) and its adjuvant potentials on the immune responses of ICR mice against ovalbumin (OVA) were evaluated. BCS showed a slight haemolytic effect, with its haemolytic percents being 3.32% and 1.19% at the concentrations of 500 and 250 μg/ml, respectively. ICR mice were immunized subcutaneously with OVA 100 μg alone or with OVA 100 μg dissolved in saline containing aluminium hydroxide gel (Alum, 200 μg), QuilA (10 and 20 μg) or BCS (50, 100 or 200 μg) on Days 1 and 15. Two weeks later (Day 28), concanavalin A (Con A)-, lipopolysaccharide (LPS)- and OVA-stimulated splenocyte proliferation and OVA-specific antibodies in serum were measured. BCS significantly enhanced the Con A-, LPS-, and OVA-induced splenocyte proliferation in the OVA-immunized mice especially at a dose of 100 μg (P < 0.05 or P < 0.001). OVA-specific IgG, IgG1 and IgG2b antibody levels in serum were also significantly enhanced by BCS compared with OVA control group (P < 0.01 or P < 0.001). Moreover, no significant differences (P > 0.05) were observed between enhancing effect of BCS and QuilA on the OVA-specific IgG2b antibody responses to OVA in mice. In conclusion, the results suggest that BCS could be safely used as adjuvant with low or non-haemolytic effect.