A new type of biological response modifier from Chlorella vulgaris which needs protein moiety to show an antitumour activity

Abstract

An immunopotentiator obtained from Chlorella vulgaris strain CK22, showed antitumour effects against various lines of syngeneic tumours, especially by intratumour administration. The immunopotentiator exhibited far greater antitumour activity against a rechallenged tumour than against the primary-inoculated tumour in Meth A and BALB/c or CDF1 mouse systems. The antitumour effect was at least comparable to that of a streptococcal preparation, OK-432, which has been widely used for clinical immunotherapy. The active compound was fractionated by anion-exchange and affinity chromatography monitoring by the Meth A rechallenge system. The most active fraction, Q2C2, consisted of galactose-rich carbohydrate (56.1%) and protein (36.3%). Antitumor activity disappeared after protease digestion, but was stable for extreme treatments of acid, alkali, heat and carbohydrate degradation. These facts indicate that the protein moiety of the glycoprotein is mainly related to express the antitumour activity.