Induction of antitumor L3T4-positive T cells by OK-432 at tumor sites in mice

Evidence that eosinophil infiltration in the OK-432/fibrinogen-injected Meth-A tumor in mice is mediated by locally produced IL-5

It was previously demonstrated that a single injection of OK-432 (a penicillin-treated freeze-dried Streptococcus) mixed with fibrinogen into cancer tissues induces marked infiltration by eosinophils of the tumor stroma and leads to tumor necrosis. In the present study, we examined mechanisms regulating the local accumulation of eosinophils and the role of infiltrating eosinophils in tumor regression using the OK-432/fibrinogen injected Meth-A fibrosarcoma tumor. After injection of OK-432/fibrinogen into the tumor on the left flank of the BALB/c mice, eosinophil infiltration became obvious in the tumor stroma on day 3 following the accumulation of macrophages and neutrophils, was massive on day 5 and decreased by day 10. After the decrease in the infiltration of eosinophils, the tumor injected with OK-432/fibrinogen diminished markedly in size with ulceration as compared with control. Northern blot analysis revealed that expression of IL-5 mRNA in the tumor tissue was not detected on day 0, was significantly on day 3, reached the maximum on day 5, and thereafter decreased by day 10. Although intraperitoneal injection of rat anti-IL-5 monoclonal antibody in tumor bearing mice prior to OK-432 injection inhibited the infiltration of eosinophils, the antitumor effects of OK-432 persisted. In the blood, neither eosinophilia nor IL-5 activity was recognized during the course of the experiment. These results suggest that intratumoral injection of OK-432/fibrinogen induces local production of IL-5, which in turn recruits eosinophils into the tumor tissue, however, the infiltrating eosinophils do not play an important role in tumor regression.

Local injection of OK432 can augment the TH1-type T-cell response in tumor-draining lymph node cells and increase their immunotherapeutical potential

The effect of local injections with streptococcal preparation OK432 on the therapeutical potential of tumor-draining lymph node (LN) cells was investigated in mice. Peritumoral injections with OK432 on days 2, 4, 6, 8 and 10 showed no effect on the in vivo growth of s.c. inoculated B16F10 melanoma. The B16F10-draining OK432-treated LN cells, however, showed a high level of anti-B16F10 cytolytic activity after an in vitro culture first with both anti-CD3 monoclonal antibody (MAb) and activated B cell blasts, and subsequently with interleukin (IL)-2 without in vitro restimulation. Such in vitro expanded LN cells showed a remarkable antitumor effect against pulmonary metastasis of B16F10 melanoma, even without the concurrent administration of IL-2. In addition, the therapeutical protocol was also found to be moderately effective against poorly immunogenic MCA fibrosarcoma, and the in vivo antitumor effect was specific to the tumor from which the LNs were harvested. Interestingly, 2 kinds of comparative analyses of the cytokines revealed that the B16F10-bearing state induced the draining LN cells to develop a Th2-type response. However, the OK432 treatment was able to effectively augment their Th1-type response. Collectively, our results suggest that peritumoral injections with OK432 significantly increased the therapeutical potential of the tumor-draining LN cells by augmenting their Th1-type response.

Mechanistic analysis of high antitumor effect of intradermal administration of lipopolysaccharide from Pantoea Agglomerans

Lipopolysaccharide from Pantoea Agglomerans (LPSp) has a remarkably high antitumor activity even against poorly immunogeneic tumors when given by intradermal injection combined with cyclophosphamide (CY). We have extended this study to gain an insight into the mechanism of this antitumor effect, and especially into the induction of cell mediated immunity. In immunohistological studies, extensive necrosis and marked infiltration of the inflammatory cells at the tumor were observed after intradermal injection of LPSp combined with CY, but not after CY alone or after no treatment. The cells around the tumors were mostly neutrophils and macro phages (Mac 1+); T cells (CD4+, CD8+) were also present. The serum levels of cytokines, induced after intradermal injection of LPSp, were determined and compared with intravenous administration of LPSp or recombinant TNF-SAM2. TNF-alpha, IL-1, IL-6 and GM-CSF were measured by ELISA as a marker of cytokine induction. The peak level of TNF-alpha induced by intradermal injection of LPSp was about 5000 pg ml-1, which was considered relatively small since this level was observed even in clinical trial. There seems to be a longer period of release of TNF-alpha after an intradermal injection than after an intravenous injection. This may produce the remarkably high antitumor effect of the intradermal injection. The antitumor effect of intradermal administration combined with CY was evaluated in nude mice to clarify the role of T cells in high antitumor activity. In this experiment, antitumor activity was found to be much less in BALB/c nu/nu mice without regression, while complete regression was frequently observed in syngeneic mice, showing the crucial role of T cells in this treatment. These observations suggest that intradermal administration of LPSp in combination with CY continuously releases and induces not only extensive necrosis of the tumor but also cell mediated antitumor immunity, which may be indispensable for complete regression of the tumor. Clinical application of this treatment for advanced cancer patients is in progress.

OK-432 therapy for lymphangioma in children: why and how does it work?

Intralesional injection of OK-432 (lyophilized incubation mixture of group A Streptococcus pyogenes of human origin) is safe and effective therapy for lymphangioma. The authors evaluated the mechanism of this therapy in 6 patients who had cystic lymphangioma. The intracystic fluid of the cystic lymphangioma was aspirated before and after (on days 1 and 4) the OK-432 therapy. Changes in cell populations and cytokine productions in each aspirated fluid were analyzed. White blood cells in the intracystic fluid increased markedly in number. Before OK-432 therapy, 96% of the intracystic white blood cells were lymphocytes, and the remaining were neutrophils and macrophages. On day 1, the percentages of neutrophils and macrophages increased to 72% and 21%, respectively. On day 4, the percentage of lymphocytes increased to 72%. Flow cytometry analysis using monoclonal antibodies showed that the number of natural killer cells (CD56+) and T cells (CD3+) had increased. The activity of cytotoxic tumor necrosis factor (TNF) and interleukin-6 increased immediately after OK-432 injection and remained high in titer until day 4. These findings suggest that the white blood cells induced and activated by OK-432, and the cytokines (including TNF) produced by these cells increased the endothelial permeability, and thus the accelerated lymph drainage and increased lymph flow let to shrinkage of the cystic spaces.

Combination chemo-immunotherapy of murine solid tumor with OK-432, G-CSF, IL-2, and chemotherapeutics

An experimental tumor model was previously established in which BALB/c mice could survive the otherwise fatal intraperitoneal (i.p.) inoculation of BAMC-1 fibrosarcoma cells if the mice were treated with five sequential i.p. injections of OK-432 (a potent BRM) starting 2 days after tumor inoculation. In the present study, although a single i.p. injection of OK-432 alone on day 2 was not enough to cure the tumor-bearing mice, a combination therapy, an injection of OK-432 (5 mg/kg) on day 2 followed by injection of G-CSF (50 micrograms/kg) on day 3, could eradicate the tumor cells in more than 80% of the mice. In contrast to this ascites tumor model, solid tumors induced by intradermal transplantation of BAMC-1 tumor cells were resistant to the combined treatments with OK-432 and G-CSF, dying within 60 days. However, when these mice received a combined chemoimmunotherapy with cisplatin, OK-432, G-CSF and IL-2, starting on day 4, the tumors had regressed, and were completely eradicated. When the same treatment was started as late as day 8, no significant therapeutic effect was observed. Even at this advanced stage, however, it was found that a similar chemo-immunotherapy protocol using CAP-D (cyclophosphamide, epirubicin and DWA2114R) in lieu of cisplatin was extremely effective, achieving the eradication of tumors in more than 70% of the mice. These results indicated that the combination therapy with OK-432, G-CSF, IL-2, and chemotherapeutics could achieve a potent anti-tumor effect against the solid tumor, even at the advanced stage. Subsequent experiments using athymic nude mice transplanted with the tumor cells revealed that the same combination therapy showed weak tumor-regressing effects without achieving a complete cure. These results suggest that T-cells are key effectors in this type of chemo-immunotherapy of malignant tumors.

Cytokine-gene-modified tumor vaccination intensified by a streptococcal preparation OK-432

Vaccinations with tumor cells engineered to express certain cytokines have been demonstrated to induce potent and specific antitumor immunity. In our previous report, we carried out a comparative study on the ability of cytokine-gene-modified tumor vaccines to induce host immune responses, and found that irradiated tumor cells, genetically modified to secrete granulocyte/macrophage-colony-stimulating factor (GM-CSF tumor vaccine), were the most potent stimulators of systemic antitumor immunity. In this report, using the experimental tumor models in which the GM-CSF tumor vaccine was less effective in immunopotentiation, we found that the combined use of a biological response modifier (BRM) OK-432 remarkably enhanced the antitumor activity induced by the GM-CSF tumor vaccine. These data indicate the possible role of a BRM such as OK-432 to intensify further the specific tumor vaccination therapy.