Immunological evidence of a surface structure common to Streptococcus pyogenes preparation OK-432 and mouse ascites tumor cells

The presence of a common antigen between human gastric cancer cells and OK-432

Twenty two surgical specimens of gastric cancer resected after administration of OK-432 for the skin reaction test were examined to determine whether the cancer cells had the same antigens as OK-432, a product of hemolytic streptococcus cells. When the tissues were stained by the PAP method with anti-Su streptococcus antibody used as the primary antibodies, the common antigens were demonstrated in 10 (45.5%) of the 22. The presence or absence of the common antigens was independent of the degree of skin reaction to OK-432, and the relations of the common antigens to other host responses were not clear in this study. This is the first report for the presence of such common antigens between human gastric cancer and OK-432.

Antibody production useful for cytotoxicity against mouse MM2 tumor cells by peritoneal macrophages

We applied an antibody-dependent macrophage-mediated cytotoxicity (ADMC) test in order to analyze the effector mechanism of the host-mediated antitumor effects induced by OK-432. Adherent peritoneal exudate (PE) cells were obtained from each of high (C3H/He) and low (B10) responder mice treated with OK-432, and 51Cr-labeled MM2 tumor cells were used as target cells. The cytotoxic activity in vitro coincided well with the results obtained in in vivo antitumor experiments. When adherent PE cells from C3H/He mice reacted with anti-MM2 serum from B10 mice, the degree of ADMC was significantly lower than that obtained with the anti-MM2 serum from C3H/He mice. The removal of IgG1 from the anti-MM2 serum induced in B10 mice resulted in the enhancement of ADMC activity. Then mean level of IgG2 in each of anti-MM2 sera from C3H/He and B10 mice was higher than in normal serum, and the IgG1 level in the antiserum from B10 mice was also higher than that in the serum from normal B10 mice. The present work suggested that the active component(s) in anti-MM2 serum participating in ADMC was a specific antibody of the IgG2 subclass, and that the inhibiting factor(s) was the IgG1 subclass.

Biological response modifier enhances the activity of natural killer cell against human cytomegalovirus-infected cells

Peripheral blood lymphocytes (PBL) from two human cytomegalovirus (CMV)-seronegative donors and eight CMV-seropositive donors were cultured for 3 days with or without the biological response modifier OK-432 and examined for lysis of K562 cells and CMV-infected MRC-5 cells. OK-432-stimulated PBL exhibited significantly greater natural killer (NK) activity than did unstimulated PBL. There was no difference in activity of NK cells in PBL prepared from CMV-seronegative and -seropositive donors. Antibody-complement depletion studies suggested that OK-432-stimulated NK activity was associated with Leu-7-positive cells. The ability of OK-432 to sustain the NK activity in PBL was decreased when the CD4-positive population of lymphocytes was eliminated by antibody-complement depletion prior to OK-432 stimulation. The ability of OK-432 to sustain the NK activity of PBL was also significantly decreased in the presence of monoclonal antibody against recombinant human interleukin-2. The results suggest that the activity of human NK cells against K562 and CMV-infected MRC-5 target cells can be sustained in vitro by OK-432-stimulated T-helper cells and that the effect of the T-helper cells is mediated, at least in part, by interleukin-2.