AUGMENTATION OF HOST-DEFENSE MECHANISMS AGAINST TUMOR BY SPERABILLIN POLYMERS, NEW BASIC PEPTIDYL BIOPOLYMERS, IN MICE

Sperabillin polymers, which have been shown recently to have antitumor activity, are new basic peptidyl polymers composed of a pseudo-peptid e antibiotic, sperabillin A. The polymers, HP-2 (MW 9990), AP-2 (MW 20 ,100) and AB-2 (MW 35,000), were found to potently activate murine per itoneal macrophages The phagocytosis-dependent respiratory burst and F cgamma receptor expression of peritoneal macrophages from C57BL/6 mice were enhanced after in vitro cultivation with these polymers. When HP -2, a representative of these polymers, was intraperitoneally injected into mice, the number of peritoneal exudate cells increased and phago cytosis-dependent respiratory burst and class II (I-A) antigen express ion of peritoneal macrophages were augmented. These macrophages showed strong inhibitory activity against the growth of murine tumor cell li nes such as EL4 lymphoma and B16 melanoma. Nitrogen oxide, tumor necro sis factor (TNF) and interleukin 1 (IL-1) might be required for this i nhibitory activity. Moreover, in mice treated with HP-2, splenocyte co unts also increased and non-specific killer activity of the splenocyte s was augmented. These results indicate that sperabillin polymers are new macrophage activators.