Adjuvant effect of Panax notoginseng saponins on the immune responses to ovalbumin in mice

In this study, the haemolytic activities of Panax notoginseng saponins (PNS) and its adjuvant potentials on the cellular and humoral immune responses of ICR mice against ovalbumin (OVA) were evaluated. We determined the haemolytic activity of PNS using 0.5% rabbit red blood cell. PNS showed a slight haemolytic effect, with its haemolytic percents being 11.59 and 3.60% at the concentrations of 500 and 250 mug/ml, respectively. Furthermore, the adjuvant potential of PNS at three dose levels on the cellular and humoral immune responses of ICR mice against ovalbumin were investigated. ICR mice were immunized subcutaneously with OVA 100 mug alone or with OVA 100 jig dissolved in saline containing aluminum hydroxide gel (Alum) (200 mug), Quil A (10 and 50 mug) or PNS (50, 100 or 200 mug) on days I and 15. Two weeks later (day 28), concanavalin A (Con A)-, pokeweed (PWM)- and OVA-stimulated splenocyte proliferation and OVA-specific antibodies in serum were measured. PNS significantly enhanced the Con A-, PWM-, and OVA-induced splenocyte proliferation in the OVA-immunized mice at a dose of 100 mug (P < 0.05 or P < 0.025). OVA-specific IgG, IgG I and IgG2b antibody levels in serum were significantly enhanced by PNS compared with OVA control group (P < 0.025). Moreover, enhancing effect of PNS on the OVA-specific IgG2b antibody responses to OVA in mice were more significant than that of Quil A (P < 0.025). In conclusion, the results suggest that PNS could be safely used as adjuvant with low or non-haemolytic effect. (C) 2004 Elsevier Ltd. All rights reserved.