Antitumor activity of polygalactosamine isolated from Paecilomyces sp. I-1 strain

The inhibitory effect of polygalactosamine (PF102), which was isolated from Paecilomyces sp. I-1 strain, on a syngeneic murine solid tumor and its antitumor mechanism were studied. After an intravenous injection of PF102, 1 microgram/kg, an increase in cell mediated and humoral immunities in mice was observed and the growth inhibition of MM46 solid tumor in vivo was also evident. Macrophages induced by PF102 into the peritoneal cavity inhibited deoxyribonucleic acid synthesis of target cells. Moreover, PF102 caused a significant increase in the incorporation of 3H-thymidine into the thymic cells and the culture supernatant of T lymphocytes, stimulated with PF102, exhibited a marked activation of the cytostatic effect of the peritoneal macrophages. Furthermore, this culture supernatant fluid was found to contain interferon (IFN). Therefore, the antitumor activity of PF102 might be due in part to the activation of the macrophage lineage cells by macrophage activating factor and/or IFN produced from T lymphocytes stimulated by PF102.