Benaxibine

The enhancement of tumor cell susceptibility to macrophage binding and cytolysis by the pretreatment of tumor cells by p-aminobenzoic acid-N-xyloside sodium salt (K-247) was investigated in the C3H/He mouse-syngeneic tumor system. Binding and cytolytic activities of Corynebacterium parvum-activated macrophages were significantly enhanced when target MM-102 and MH-134 cells were pretreated with K-247 at doses of 200 or 400 micrograms/ml, while thioglycollate-elicited macrophages showed much lower binding and lytic activities against K-247 pretreated target cells. No enhancement of these activities were observed when target cells were pretreated with D-xylose, which had no anti-tumor activity. Furthermore, in a binding assay a significant reduction of macrophage binding to target cells by the K-247 pretreated cold competitors was observed. It is suggested that target cell susceptibility to macrophage cytolytic activity might be enhanced by pretreatment with K-247, involving an initially increased target binding.

A strain of SHR which develops hypertension spontaneously is marked by a selective depression of T-cell functions associated with an early appearance of natural thymocytotoxic autoantibody and a deficiency of thymic hormone. Present results demonstrate that various immunopotentiators (IPs) such as thymostimulin (TS), PS-K, SPG, neurotropin (NSP), and K-247 partially or almost completely reversed the T-cell depression in these SHR as detected by a rosette forming test, plaque-forming assay and blastogenesic response to PHA and Con A. In contrast, these IPs had no effect on the immune responsiveness of WKA rats with normal T-cell functions. Among the IPs, NSP, which had an almost complete restorative effect on the T-cell functions of SHR, induced significant transplantation resistance to the syngeneic tumor challenge. A new synthetic product K-247 also induced a significant suppression of lethal tumor growth in SHR, though its restorative effect on T-cell functions was weak. The fact that K-247 had a suppressive effect on tumor cell growth in vitro indicates that biochemical modifications rather than immunological ones may be involved. However, none of the IPs induced antitumor resistance in normal WKA rats. These results suggest that this strain of SHR provides a useful animal model for evaluation of various IPs.