Endogenous Production of Cytotoxic Factor in Normal Mice by PSK Combined with OK-432

Abstract

Intravenous administration of the protein-bound polysaccharide, PSK, significantly stimulated OK-432-elicited endogenous cytotoxic factor (CF) production in ICR mouse serum fractions. The level of CF elicited after OK-432 administration peaked after 3 hr and declined to the basal level within 7 hr. The CF producibility depended greatly on both the dose and intervals of PSK and OK-432 administration. Among the four different PSK subfractions, the lowest molecular weight fraction (MW<50kD) had the most potent stimulation activity, but it did not exceed that of unf ractionated PSK. This is the first demonstration of the stimulation of endogenous CF production by PSK combined with an eliciting agent.