Etsuro Yanagawa

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.

Relationship of the distribution of leu-2+ cells with suppressor cell activities in the spleen and lymphnodes from gastric cancer

Tissue distributions of Leu-2+ cells in the spleen and draining lymphnodes in cases of clinical gastric cancer were investigated, with special reference to suppressor cell function. Significantly higher Concanavalin-A (Con-A) induced suppressor cell activities were evident in spleen cells (SCs), as compared with peripheral blood lymphocytes (PBLs). As for the tissue distribution, the proportion of Leu-2+ (cytotoxic/suppressor) cells within Leu-1+ cells was higher in the spleen than in the lymphnodes without metastasis. On the other hand, in lymphnodes with metastasis, the enhanced spontaneous suppressor cell activity was noted. In addition, the proportion of Leu-2+ cells within Leu-1+ cells was the greatest in the lymphnodes with metastasis, among the lymphoid organs tested. In lymphnodes without metastasis, lower suppressor cell activities were noted, and numerous Leu-3+ (helper/inducer) cells were present, while Leu-2+ cells were less frequent. NK cell activity against K-562 cells was enhanced by elimination of Leu-2+/OKT-8+ cells with complement-mediated lysis. These results suggest that Leu-2+ cells located in the spleen and lymphnodes with metastasis may predominantly act as suppressor cells and interact with effector cells.

Chemosensitivity tests in colorectal cancer patients

In order to assess the usefulness of chemosensitivity tests in the treatment of colorectal cancer, 71 tumor specimens were tested for chemosensitivity in the following assays: nude mouse isotope assay (NMIA), subrenal capsule assay (SRCA), human tumor clonogenic assay (HTCA) and adenosine triphosphate inhibition assay (ATPA). The agents examined were: mitomycin C (MMC), 5-fluorouracil (5-FU), cyclophosphamide (CPM), adriamycin (ADM) and cis-diamminedichloroplatinum (CDDP). The evaluability rates were 90.8, 93.9 and 92.3 per cent in NMIA, SRCA and ATPA, respectively, but only 42.9 per cent in HTCA. The tumor response rates were 50.8, 45.2, 16.7 and 33.3 per cent in NMIA, SRCA, HTCA and ATPA, respectively. Individual drug sensitivity rates differed among all 4 assays, ranging from 0 to 33.3 per cent. In the arbitrary judgment of the 4 assays, the most sensitive agent was CDDP, followed by CPM, ADM, 5-FU and MMC. In the prospective study, predictive accuracy rates of the clinical responses were 81.3 66.7, 100, 100 and 76.5 per cent in NMIA, SRCA, HTCA, ATPA and the arbitrary judgment, respectively. A significant correlation between the survival time and the results of SRCA was detected retrospectively. These results suggested that colorectal cancer might not be completely resistant to anticancer agents, and that chemosensitivity tests might be useful in the individual therapy of colorectal cancer patients.

Prospective randomized controlled study on bestatin in resectable gastric cancer--third report.

The efficacy of Bestatin as adjuvant immunochemotherapy for patients with resectable gastric cancer was investigated. Ninety-six patients with similar background factors were randomized into two groups; a control group and an experimental group, the patients in the experimental group receiving a daily oral dose of 60 mg Bestatin over a long period. All 96 patients were treated with a bolus intravenous injection of mitomycin C (MMC) plus oral administration of tegafur (FT-207, FT). The survival rate of the patients in the MMC+FT+Bestatin group was more favorable than that of the patients in the MMC+FT group, but the difference was not statistically significant. The survival rates of the MMC+FT+Bestatin group patients intthe stratification of stage III+IV and positive histological serosal invasion, ps(+), were significantly superior to those of the MMC+FT group patients (Logrank test: p<0.05). Moreover, in patients with positive histological serosal invasion, the recurrence of peritoneal dissemination was significantly suppressed in the MMC+FT+Bestatin group.

Reduction of suppressor cell activities of human peripheral blood lymphocytes by a streptococcal preparation, OK-432

The effect of a streptococcal preparation, OK-432 on suppressor cell activities of peripheral blood lymphocytes was investigated. Suppressor cell activities were significantly reduced when they were generated in vitro by concanavalin A (Con A) in the presence of OK-432. However, the reduction of suppressor cell activities was not observed when OK-432 was added in the effector phase. Similarly, a significant reduction of prostaglandin E2 (PGE2)-induced suppressor cell activities by OK-432 was observed. No increases of either T-cells with Fc receptors for IgG or OKT8 reactive T-cells were observed after Con A stimulation in the presence of OK-432. The suppressive effect of the soluble suppressor factors (SSF) was not abrogated by OK-432 and the release of SSF from cells activated by Con A was not found in the presence of OK-432. Thus, it is suggested that OK-432 might interfere with the induction of suppressor cells, but not with the expression of their activities.

Prognostic significance of lymphocyte proliferative responses to mitogens in gastric cancer patients.

In 501 Japanese patients with gastric cancer, the relationships between preoperative lymphocyte proliferative (LP) responses to mitogens and prognosis of patients were evaluated. Peripheral blood lymphocytes were cultured in the presence of either autologous or allogeneic serum and their LP responses to phytohemagglutinin (PHA) and pokeweed mitogen were investigated. An apparent inverse relationship between LP responses and stage of the disease was found in LP responses to PHA in the presence of autologous serum. The survival rate of patients with higher responses was significantly greater than of those with lower responses, when LP responses to PHA in the presence of autologous serum served as the criterion. Probabilities of staging which were computed on the basis of LP response to PHA affirmed the reciprocal relationship between LP responses and stage of the disease. From these results, it is concluded that evaluation of LP responses may be a valuable tool in the assessment of the clinical stage and in the prediction of prognosis.

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.

The histological assessment and evaluation of a 4 day subrenal capsule assay by the percentage inhibition of DNA/protein

A four day subrenal capsule assay was investigated in order to determine its ability to clinically predict tumor chemosensitivity. To establish more objective and accurate evaluation criteria, a histological assessment and measurement of the DNA and protein content of excised tumor implants was conducted in ddY mice. The histological studies provided qualitative results concerning the percentage of cancer cells in the xenograft, the number of mitoses, the amount of necrosis, and the extent of lymphocytic infiltration. The DNA content was measured by a modified version of the Schmidt-Thannhauser-Schneider method and the protein content was estimated using the Bio-Rad protein assay. The percentage of cancer cells in the xenograft correlated poorly with the relative increase in tumor size, weight and the percentage inhibition of DNA/protein (per cent DNA/protein), however, the per cent DNA/protein correlated well with the clinical effects in 85.7 per cent of the tumors studied. Moreover, the histological assessment information was only consistent with those results obtained for per cent DNA/protein in the control group.

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.