Augmentation of cytotoxicity of regional lymph node lymphocytes of gastric cancer after intratumoral injection of OK-432

Although regional lymph node lymphocytes (LNL) are thought to be a barrier of the immunological surveillance, their natural cytotoxicity is strongly suppressed. In this study, an immunopotentiator OK-432 (10K.E.) was injected into gastric cancer lesions under endoscopy 1 week before operation, and the effects on the cytotoxicity of LNL were examined by single cell assay. This assay is characterized by assessment of killer cell frequency in preventing the killer cells from recycling by their fixation in agarose, and by direct microscopic observation of both binding and killing phases. NK sensitive cell line K562 was used as target cells. By intratumoral injection of OK-432, the killer cell frequency of LNL in 8 out of 20 cases was elevated to almost equal level as that of peripheral blood lymphocytes. In clinical stages these 8 cases belonged to early stages (stage I 7 cases, stage II 1 case). In LNL subsets of OK-432 injected cases, the percentage of OKT8 positive cells was decreased and the ratio of OKT4 and OKT8 was significantly increased compared with non-injected group.