A NEW-TYPE OF BIOLOGICAL RESPONSE MODIFIER FROM CHLORELLA-VULGARIS WHICH NEEDS PROTEIN MOIETY TO SHOW AN ANTITUMOR-ACTIVITY

An immunopotentiator obtained from Chlorella vulgaris strain CK22, sho wed antitumour effects against various lines of syngeneic tumours, esp ecially by intratumour administration. The immunopotentiator exhibited far greater antitumour activity against a rechallenged tumour than ag ainst 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 s treptococcal preparation, OK-432, which has been widely used for clini cal immunotherapy, The active compound was fractionated by anion-excha nge and affinity chromatography monitoring by the Meth A rechallenge s ystem. The most active fraction, Q2C2, consisted of galactose-rich car bohydrate (56.1%) and protein (36.3%), Antitumour activity disappeared after protease digestion, but was stable for extreme treatments of ac id, alkali, heat and carbohydrate degradation. These facts indicate th at the protein moiety of the glycoprotein is mainly related to express the antitumour activity. (C) 1998 John Wiley & Sons, Ltd.