IMMUNOCHEMOTHERAPY OF TRANSPLANTED KMT-17 TUMOR IN WKA RATS BY COMBINATION OF CYCLOPHOSPHAMIDE AND IMMUNOSTIMULATORY PROTEIN-BOUND POLYSACCHARIDE ISOLATED FROM BASIDIOMYCETES

Abstract

The protein-bound polysaccharide Kureha (PS-K) isolated from Basidiomycetes was used in combination with cyclophosphamide (CY) for the treatment of a 3-methylcholanthrene-induced KMT-17 fibrosarcoma in WKA/Mk rats. A single administration of PS-K exhibited no inhibitory effect on the growth of s.c.-inoculated KMT-17 tumor at any timing and dose. PS-K exhibited a marked antitumor effect when it was combined with CY. The effect of PS-K depended on the combination timing of PS-K CY. A marked antitumor effect was observed when PS-K was administered before CY but not if it was given after CY or before tumor inoculation. When PS-K was administered on day 1 followed by CY on day 3, the highest survival rate of 78.5% (11 of 14) was obtained. Delayed hypersensitivity response of rats to KMT-17 was investigated by radioisotopic footpad assay. On day 12, the hypersensitivity response in rats treated with PS-K on day 1 and CY on day 3 was significantly higher than that in nontreated rats, indicating an enhanced specific immunity to KMT-17 possibly resulting in a marked antitumor effect.