THE MECHANISM OF LOCALLY ENHANCED PRODUCTION OF TUMOR-NECROSIS-FACTOR-ALPHA IN TUMOR-TISSUES BY THE ADMINISTRATION OF A NEW SYNTHETIC LIPID-A ANALOG, ONO-4007, IN HEPATOMA-BEARING RATS

ONO-4007 is a new synthetic lipid A analog with low endotoxic activiti es. We previously found that ONO-4007 induced the production of tumor necrosis factor (TNF)-alpha in rat hepatoma KDH-8 tumor tissues and br ought about the regression of transplanted KDH-8 cells. By contrast, O NO-4007 did not induce TNF-alpha production in spleens and sera 90 min after treatment. In the present study we attempted to elucidate how O NO-4007 induces TNF-alpha production in tumor tissues locally. We foun d that extracellular matrix including gelatin, fibronectin and Matrige l(TM) did not induce TNF-alpha production in splenocytes treated with ONO-4007 in vitro. However, splenocytes co-cultured with cKDH-8/11 tum or cells in the presence of ONO-4007 produced more TNF-alpha than sple nocytes cultured by themselves in the presence of ONO-4007. The stimul ation of cKDH-8/11 cells in the presence of ONO-4007 for splenocytes t o produce TNF-alpha depended on the type of contact between the cells. The cKDH-8/11 cells fixed in formalin were not able to induce TNF-alp ha production of splenocytes even in the presence of ONO-4007. However , syngeneic fibrosarcoma cell line KMT-17/A3, allogeneic hepatocellula r carcinoma cell line LDH and rat lung endotherial cell line RLE induc ed TNF-alpha production in splenocytes, but their stimulation was weak er than that of cKDH-8/11. The soluble form of the cKDH-8/11 cell memb rane did not stimulate splenocytes to produce TNF-alpha in the presenc e of ONO-4007. cKDH-8/11 cells did not stimulate the splenocytes devoi d of macrophages to produce TNF-alpha in the presence of ONO-4007.