Immunohistochemical characterization of lung cancer-associated monoclonal antibodies

Four IgM monoclonal antibodies against an intermediate cell type small cell lung cancer (SCLC) cell line (SBC-1) were produced and characterized. Reactivities of the antibodies to cell lines were tested by membrane immunofluorescence, and the reactions with normal and neoplasma tissues were analyzed using an indirect immunoperoxidase technique. Each of the 4 antibodies reacted with lung cancer cell lines and lung cancer tissues, but did not exhibit lung cancer histology-type specificity. The 4 antibodies reacted with normal bronchiolar and digestive gland tissues, and the antibody-reactive antigens were shown to be a gland-tissue differentiation antigen. The antigen was expressed on O type red cells, was not expressed on other erythrocytes and was undetectable in intermediate SCLC tissues. This may represent the epitope-difference of the antigen recognized by the antibodies. None of the antibodies reacted with oat SCLC, but intermediate and non-small lung cancer reacted with the antibodies. This result shows the antigen-similarity of intermediate SCLC with non-small lung cancer.