Immunologic Enhancement Activity Of A Polysaccharide Isolated From The Fruit Of Physalis Alkekengi L.

Physalis alkekengi L. of the family of Solanaceae is a traditional Chinese herbal plant distributed abundantly in the northeast region of China. It has been reported to have many ethnopharmacological properties including anti-inflammatory, anti-cold, anti-cough and anti-fungal activities. Some active components from P. alkekengi, such as physalin, alkaloids, and flavone, have been investigated. However, no specific studies on polysaccharides isolated from P. alkekengi fruit have been carried out. The studies were conducted to investigate immunologic enhancement of a polysaccharide (designated PPSB) purified from the mature fruit of P. alkekengi L. .PPSB used for detecting the immunological enhancement in mice was isolated with hot water from the fruit of P. alkekengi, fractionated with different concentration of ethanol and purified by Sepharose CL-6B gel filtration chromatography.Male ICR mice were immunized subcutaneously with ovalbumin (OVA) alone, OVA/PPSB or OVA/Alum (positive control), and humoral and cellular immune responses against OVA were detect to evaluate the immunological enhancement of PPSB.The results showed PPSB (at dose of 100μg/mouse) significantly enhanced OVA-specific antibody titers (IgG, IgG1, IgG2b), ConA, LPS or OVA-induced splenocyte proliferation, proportion of CD4+ and CD8+ T lymphocytes in spleen, delayed-type hypersensitivity (DTH) response when compared with mice injected with OVA alone. Importantly, PPSB (at dose of 100μg/mouse) augmented greatly IgG1, IgG2b antibody titers, ConA, LPS or OVA-induced splenocyte proliferation, DTH response, and the induction of CD4+ and CD8+ T lymphocytes, while alum induced only IgG1 antibody titer and the proportion of CD4+T lymphocytes.These findings indicate that PPSB can evoke the stronger humoral and cellluar immunity in mice immunized with OVA which is more effective than alum adjuvant. Thus, PPSB is considered as a promising adjuvant eliciting both Th1 and Th2 responses to improve the efficacy of vaccine.