Monoclonal antibody to the streptococcal preparation OK-432: tissue OK-432 localization and analysis of interaction between OK-432 and macrophages or NK cells in human salivary adenocarcinoma-bearing nude mice given OK-432.

An immunoglobulin M mouse monoclonal antibody (MAb) to the streptococcal preparation OK-432, TS-1, was generated. The TS-1 antigen is a carbohydrate epitope. This antigen is stable upon fixation and embedding in paraffin. The tissue and cellular OK-432 localization in human salivary adenocarcinoma-bearing nude mice given OK-432 intratumorally was examined by various methods according to the immunological procedures using the purified TS-1 MAb. The presence of OK-432 antigen recognized by TS-1 MAb was clearly observed in the tumor as well as the spleen and lung 24 or 48 h after OK-432 administration, whereas transfer of OK-432 from the site of injection to the organs, such as liver and kidney, was rarely seen. The presence of OK-432 antigen in some immunocompetent cells, as defined by Mac-1 antigen or asialo GM1 antigen, was observed by the double-antibody labeling technique in the tumor and spleen from tumor-bearing nude mice. Moreover, interaction between OK-432 and macrophages or natural killer (NK) cells in relation to expression of interferon (IFN) in tumor-bearing nude mice given OK-432 was observed. Consequently, significant increases of Ia-positive or Ia-negative macrophages, NK cells as well as IFN-alpha/beta- or IFN-gamma-positive cells in the tumor and/or spleen were found when compared with those without OK-432 administration.