POLYSACCHARIDE PEPTIDE (PSP) RESTORES IMMUNOSUPPRESSION INDUCED BY CYCLOPHOSPHAMIDE IN RATS

Polysaccharide peptide (PSP) is a protein-bound polysaccharide extract ed from an edible mushroom, Coriolus versicolor. Effects of PSP (2g/kg /day) on cyclophosphamide (CPA, 40 mg/kg/2 days)-induced immunosuppres sion were investigated by determining lymphocyte proliferation. Natura l Killer (NK) cell function, IgG and IL-2 concentration, WBC count and the weight of organs after rats were treated with or without CPA in t he presence or absence of PSP. The results demonstrated that PSP posse ssed immunopotentiating effect, being effective in restoring CPA-induc ed immunosuppression such as depressed lymphocyte proliferation, Natur al Killer cell function, production of white blood cell and the growth of spleen and thymus in rats as well as in increasing both IgG and IL -2 production on which CPA did not have significant effects under the conditions of our experiments. PSP can partly restore CPA-induced immu nosuppression. Based on our findings and the data accumulated so far, it was suggested that PSP should be considered as an useful adjuvant e specially combined with CPA or other chemotherapy in clinical treatmen t of cancer patients. The mechanism by which PSP restores the immunosu ppression induced by CPA is unclear.