Immunohistochemical study on the localization of the epitope defined by a human saliva-specific mouse monoclonal antibody (P4-5C).

A novel mouse monoclonal antibody (P4-5C) has been developed which recognizes the core portion of the protein carrying ABO(H) blood group antigens in human saliva. This proved to be specific for human saliva using immunochemical investigations such as enzyme-linked immunosorbent assay, Ouchterlony method and counter-immunoelectrophoresis. By light and electron microscope studies with immunohistochemical techniques using this human saliva-specific P4-5C as primary antibody, it was shown that P4-5C reacted specifically and exclusively with mucus from the mucous gland cells of human salivary glands. P4-5C reacted neither with the mucous gland cells of other primates (hamadryas baboon, Japanese monkey and Rhesus monkey) and four mammals (dog, cat, rabbit and mouse) nor with other human tissues. The epitope on the core portion of the ABO(H)-carrying protein was defined by P4-5C and could be discriminated from the epitope of ABO(H) blood group antigens using immunoelectronmicroscopy, although these 2 epitopes were localized relatively close to each other. The P4-5C monoclonal antibody can be also used for morphological species identification of tissue specimens from submandibular glands.