KM195 as an immunohistochemical marker of adenocarcinoma of the lung

Abstract

In order to improve the diagnosis of lung carcinoma, in which a complicated histologic pattern is present, the immunohistochemistry of 119 adenocarcinomas, 65 squamous cell carcinomas, 12 small cell carcinomas, 18 large cell carcinomas, and 15 metastatic adenocarcinoma in the lung were evaluated using a monoclonal antibody, KM195, against lung carcinoma, and compared with the immunohistochemical results using anti-human cytokeratin (CAM 5.2) and other monoclonal antibodies. Formalin-fixed, paraffin-embedded tissues were stained using the labeled streptavidin-biotin method. Extracts from fresh tissue homogenate, after fractionation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, were transferred by Western blotting and stained with KM195. The anti-lung adenocarcinoma, murine, monoclonal antibody KM195 (IgG), was positive in 107 of 119 adenocarcinomas (90%), in 15 of 18 large cell carcinoma (83%), in three of 65 squamous cell carcinomas (5%), 13 of 15 (87%) metastatic adenocarcinoma in the lung, and was negative in 12 small cell carcinomas ( P < 0.001). KM195-bound protein of primary and metastatic adenocarcinoma in the lung cases concentrated at about 40 kDa. In contrast, CAM 5.2 was positive in 52 of 67 (78%) adenocarcinomas, 10 of 62 (16%) squamous cell carcinomas, and was negative in six small cell carcinomas. These results suggest that the immunohistochemistry for KM195 may be a more useful marker over CAM 5.2 for the diagnosis of pulmonary adenocarcinoma.