cis-Diamminedichloroplatinum and 5-fluorouracil are potent inducers of the cytokines and natural killer cell activity in vivo and in vitro.

It has been reported that certain chemotherapeutic agents exhibit effects that enhance the antitumor host responses in the patients with malignant diseases. In the present study, we investigated whether cis-diamminedichloroplatinum (cisplatin) and 5-fluorouracil (5-FU) may induce cytokines and effector cells with antitumor efficacy in vivo and in vitro. The cultivation of human peripheral blood mononuclear cells (PBMC) in the presence of cisplatin (0-1.0 microg/ml) or 5-FU (0-5.0 microg/ml) resulted in the significant augmentation of natural killer (NK) and lymphokine-activated killer (LAK) cell activities as well as generation of interferon (IFN) gamma, tumor necrosis factor (TNF) alpha, beta interleukin(IL)-1beta, IL-6 and IL-12 in vitro. In addition, all of these activities were almost completely neutralized by addition of anti-asialoGM1 antibody and complement (P < 0.05). In an in vivo model, the administration of anti-asialoGM1 antibody significantly shortened the survival time extended by the treatment with cisplatin or 5-FU (P < 0.05), both on nude mice bearing salivary gland tumors and on syngeneic MethA-tumor-bearing BALB/c mice. Furthermore, high levels of NK and LAK activities and significant increases of the numbers of cells positive for asialoGM1, IFNgamma, TNFalpha, or IL-1beta were detected in the spleen cells derived from animals given cisplatin or 5-FU as compared with those given saline (P < 0.001-0.05). These findings clearly indicate that cisplatin and 5-FU are potent inducers of several types of cytokines and effector cells carrying antitumor activity mediated by asialoGM1-positive cells (mainly NK cells) for the most part, and that these abilities are closely associated with the in vivo antitumor effect of these agents.

Purification and characterization of interferon-gamma-inducing molecule of OK-432, a penicillin-killed streptococcal preparation, by monoclonal antibody neutralizing interferon-gamma-inducing activity of OK-432.

An immunoglobulin M mouse monoclonal antibody (MAb) to streptococcal preparation OK-432, TS-2, was generated. The TS-2 MAb showed positive reaction with butanol extract of OK-432 and fungal, branched (1-->3)-gamma-glucans (lentinan and schizophyllan) as well as lipoteichoic acids. Moreover, the interferon (IFN)-gamma-inducing activity of OK-432 was neutralized by TS-2 MAb. The affinity column of butanol extract of OK-432 on CNBr-activated Sepharose 4B-bound TS-2 antibody was prepared and the fractions containing IFN-gamma-inducing activity were eluted. The polysaccharide sample carrying the IFN-gamma-inducing activity with a molecular weight of 700,000 was destroyed by treatment with acid or sodium metaperiodate, but was stable to treatment with heat, alkali, pronase, or neuraminidase. Survival time of human salivary adenocarcinoma-bearing animals given a combination of the polysaccharide sample purified from butanol extract of OK-432 and TS-2 MAb was significantly shorter compared with that of the tumor-bearing animals given only the purified polysaccharide sample of OK-432. Moreover, a high level of effector cell activity in natural killer (NK) and lymphokine-activated killer (LAK) assays and significant increase of IFN-gamma-positive cells or asialo-GM1-positive cells were detected in the spleen cells from the animals given the polysaccharide sample purified from butanol extract of OK-432. These findings indicate that the polysaccharide sample purified by the affinity chromatography of butanol extract of OK-432 on CNBr-activated Sepharose 4B-bound TS-2 MAb carries the IFN-gamma-inducing activity of OK-432 and marked antitumor activity.