The antitumor effects of locally injecting human peripheral blood mononuclear cells treated with OK-432 into the tumor site: the possible role of a tumor growth inhibitory factor (TGIF).

The production of a tumor growth inhibitory factor (TGIF) was induced in human peripheral blood mononuclear cells (PBMC) by a streptococcal preparation, OK-432, in vitro. The antitumor effect of locally injecting PBMC treated with OK-432 into the tumor site was studied. PBMC were collected from patients with gastric cancer 5 to 12 days before their operation, and cultured with OK-432 for 24 hr in vitro. After the culture, the PBMC were washed thoroughly to eliminate the OK-432. The washed PBMC went on producing TGIF for more than 72 hr in vitro in the absence of OK-432. A small number of TGIF-producing PBMC, approximately 10(7) cells, were injected around the lesion under endoscopic observation. A remarkable antitumor effect was observed in 2 out of 10 cases of resectable gastric cancer. Histological examinations indicated that the antitumor effect is due to antitumor cytokines such as TGIF produced by PBMC rather than to the OK-432-activated PBMC themselves.