Distribution of lung adenocarcinoma-associated antigens in human tissues and sera defined by monoclonal antibodies KM-52 and KM-93.

Two monoclonal antibodies to human lung adenocarcinoma, KM-52 and KM-93, were generated by the novel immunizing procedure using mice rendered tolerant to the normal human lung (N. Hanai et al., Cancer Res., 46: 4438-4443, 1986). KM-93 recognized sialylated carbohydrate epitope on the antigen different from CA19-9 and DU-PAN-2, while KM-52 recognized the protein antigen. Both antigens were different from carcinoembryonic antigen, alpha-fetoprotein, and beta 2-microglobulin. Distribution of KA-52 and KA-93, the antigens recognized by KM-52 and KM-93, respectively, in various tissues and sera was investigated. In immunoperoxidase staining, KM-93 reacted strongly and frequently with tumor cells of lung adenocarcinoma and partially with those of lung squamous cell carcinoma, large cell carcinoma, and small cell carcinoma. In normal adult and fetal tissues, KA-93 was expressed on the surface of a small number of cells of the lung, pancreas, liver, kidney, and bone marrow. KM-52 reacted selectively with tumor cells of adenocarcinoma among four different histological types of lung carcinoma. In normal adult and fetal tissues, KA-52 was distributed on a small number of cells of the lung, stomach, intestine, and pancreas. Of the two monoclonal antibodies, KM-93 could be used in detecting the antigen in sera of patients with lung cancer. The KA-93 level in sera was determined by the sandwich-type enzyme-linked immunosorbent assay. Serum with a high KA-93 level was found in 34 of 70 patients with lung adenocarcinoma (48.6%), one of 67 healthy adults (1.5%), and none of 32 patients with benign diseases (0%). Combined detection by KA-93 with KA-32, a new tumor marker of lung squamous cell carcinoma (N. Hanai et al., Cancer Res., 46: 5206-5210, 1986), elevated the positive percentage in patients with lung squamous cell carcinoma (52.7%) and with lung adenocarcinoma (59.5%). These results suggested that KM-52 and KM-93 would be potential monoclonal antibodies in immunohistological diagnosis and serum diagnosis of lung adenocarcinoma, respectively.