Nobutoshi Baba

Blocking of lymphocyte surface binding sites for the soluble suppressor factor by protein-bound polysaccharide, PSK

The ability of protein-bound polysaccharide (PSK) to block the suppressive activity of soluble suppressor factor (SSF) was investigated. The suppressive activity of SSF derived from U-937 cells on phytohemagglutinin (PHA)-induced lymphocyte proliferative (LP) response was significantly reduced in the presence of PSK. The release of SSF was not inhibited by the treatment of U-937 cells with PSK. The suppressive activity of SSF on LP response to PHA was significantly decreased by the pretreatment of responder lymphocytes with PSK. Studies to determine lymphocyte receptor activity were performed. PSK competed with wheat germ agglutinin (WGA) which recognized the same receptor as SSF on the surface of the lymphocyte. Neither PSK nor serum competed with anti-CD4 monoclonal antibody. Thus, PSK may inhibit SSF-mediated suppression by competing for specific binding sites on the surface of responder lymphocytes.

The clinical efficacy of intratumoral OK-432 administration in advanced cancer patients

The clinical efficacy of intratumoral (IT) OK-432 immunotherapy in advanced cancer patients was investigated. Furthermore, the infiltration of lymphocyte subsets into the tumor tissues after the IT administration of OK-432 was also immunohistologically examined in order to analyze the mechanism of action of OK-432 immunotherapy. Forty-four patients with advanced cancer were treated with IT OK-432 immunotherapy. Ten KE (1 mg) of OK-432 was given either daily or on every second day and repeated as often as possible, the mean frequency of OK-432 injections being 18.1±14.5 times, ranging between 5 and 25 administrations. Thirty-one of the 44 patients were evaluable, 3 of whom (9.7 per cent) developed a partial response and 5 (16.1 per cent) a minor response. Intratumoral OK-432 immunotherapy, however, did not necessarily prolong the survival time. Leu 1, 3 and 7 reactive cells infiltrated into the tumor tissues treated by OK-432 injection, more frequently, when compared with cells which had been treated by recombinant TNF injection. Thus, it was suggested that IT OK-432 immunotherapy might be effective for the local control of tumor growth through the host mediated action, and that, in combination with systemic therapy, may enhance the clinical effects and prolong the survival time in advanced cancer patients.

The analysis of lymphocyte surface receptors recognized by wheat germ agglutinin for negative regulation of immune responses in cancer patients

The population of peripheral blood lymphocytes expressing surface receptors for a lectin, wheat germ agglutinin (WGA), which has been shown to recognize the same receptors as the soluble immune suppressor factor (SISF) elaborated from suppressor cells on the lymphocyte surface, was analyzed by using fluorescein isothiocyanate-conjugated WGA on flow cytometry in cancer patients. It was found that the populations of WGA+ lymphocytes in cancer patients were significantly higher than those in either normal volunteers or patients with benign disease and increased with progress of the tumor. The populations decreased after treatment in patients who underwent curative resection of the tumor and in responders of immunochemotherapy but not in those who received non-curative surgery or in non-responders. It was suggested that the increase of receptors for SISF on the lymphocyte surface might play an important role in the negative regulation of immune responses in cancer patients and that WGA might be a useful parameter for immunosuppression.

Interference of the induction of suppressor cells by a streptococcal preparation, OK-432 through the blocking of suppressor inducer T-cells

The effect of OK-432 on suppressor inducer T cells in the generation of suppressor cells was investigated to determine its mechanism of action as an immunopotentiating agent. Suppressor cell activities induced by sera from patients with advanced cancer (stage III, IV or recurrence) were found to be as high as those induced by Con-A. Suppressor activity induced by Con-A or serum from cancer patients resided in CD8+ T cells, although CD4+ T-cells were required for the induction of suppressor cells. Significant increases in the CD4+2H4+ T cell population after stimulation with either Con-A or sera from the advanced cancer patients were observed when compared with stimulation by normal serum. Stimulation with Con-A induced suppressor cells as well as a significant increase of CD4+2H4+ T-cells. The presence of OK-432 during the generation of suppressor cells, however, significantly reduced the suppressor activity and apparently blocked the increase of CD4+2H4+ T-cells. Thus, it is suggested that OK-432 may interfere with the induction of suppressor cells through the blocking of CD4+2H4+ suppressor inducer T-cells.

The regulation of natural killer cell activity by splenic nonspecific suppressor cells and its modification in cancer patients

Spleen cells (SC), splenic venous blood lymphocytes (SVL) and peripheral blood lymphocytes (PBL) from gastric and esophageal cancer patients were simultaneously tested for natural killer (NK) and nonspecific suppressor (Ts) cell activities. Furthermore, the influence of Ts activity on the augmentation of NK activity by a biological response modifier (BRM) was also investigated. Positive Ts activities were frequently detected in the SC, SVL and PBL of advanced cancer patients. The NK activities of SC and SVL were maintained even in advanced cancer patients, though significantly depressed NK activities were observed in the PBL of advanced cases. Cancer patient SC, SVL and PBL with positive Ts activity showed low NK activities. Moreover, the NK activities of SVL and PBL were low in the patients with positive Ts activity in SC. The NK activity of normal control PBL was strongly augmented by interleukin 2, interferon and OK-432. These BRMs exhibited comparable capacities to augment the NK activities of SC, SVL and PBL with negative Ts activity in cancer patients, however, the effects of these agents seemed to be low in cells with a positive Ts activity. These results suggested that NK activity might be regulated by nonspecific suppressor cells and the presence of suppressor cells might affect the augmentation of NK activity through BRM in circulating blood lymphocytes and also in spleen cells.

Effects of the oral or intratumoral administration of OK432 on the immuno-reactivities of regional lymph nodes in gastric cancer patients

The effects of OK432, a streptococcal preparation, administered either orally (PO-OK432) or intratumorally (IT-OK432) on the immuno-reactivities of regional lymph nodes were investigated in gastric cancer patients. Although native lymph node lymphocytes (LNL) from untreated patients did not show any cytotoxicities against K562 and Raji cells, enhanced activities were found in LNL from patients administered OK432. Augmenting effects on the cytotoxicities of LNL byin vitro additional OK432, interleukin 2 or γ-interferon were remarkable in the patients given IT-OK432. Moreover, the cytotoxicities of peripheral blood lymphocytes were augmentedin vitro more strongly in patients given IT-OK432 than in those given PO-OK432. Flow cytometric analysis of LNL revealed a decrease in CD4+ cells by PO-OK432 and an increase in CD8+ cells by IT-OK432. An increase in CD4+2H4+ cells and a decrease in CD4+2H4− cells were observed in the patients given OK432, though CD8+CD11+ cells decreased by PO-OK432 while CD8+CD11+ cells increased by IT-OK432. Thus, it is suggested that LNL reactive to OK432 immunotherapy may differ between PO- and IT-OK432, and that the immunoreactivities of local lymph nodes and systemical immuno-reactivities may be highly potentiated by IT-OK432 rather than PO-OK432.

The augmentative effect of a protein-bound polysaccharide (PSK) on tumoricidal activity of the soluble factor produced by a streptococcal preparation (OK-432)-activated macrophages.

The enhancement of antitumor activities of the tumoricidal soluble factor (SF) from a streptococcal preparation (OK-432)-activated macrophages by the pretreatment with a protein-bound polysaccharide (PSK) was investigated in tumor-bearing mice.Two-step stimulations with OK-432 atin vivo priming andin vitro eliciting were required for the production of the tumoricidal SF by macrophages, and the tumoricidal activity of the SF apparently correlated with the uptake of OK-432 by macrophages at priming phase.Tumoricidal activity of the SF from OK-432-activated macrophages in proteose-peptone (P-P)-pretreated mice significantly decreased with the development of the tumor, whereas in PSK-pretreated mice did not. Pretreatment of tumor-bearing mice with PSK saved a decrease in the macrophages carrying Iak or asialo GM1 antigens and an increase in wheat germ agglutinin (WGA) receptors. Furthermore, the uptake of OK-432 by macrophages at priming phase was enhanced. The tumoricidal activity of the SF from OK-432-activated macrophages was augmented.Thus, PSK may restore the depressed functions of macrophages, and the combination therapy with PSK and OK-432 may be effective to enhance the production of tumoricidal SF in tumor-bearing mice.