An immunohistochemical study of lung carcinomas using a monoclonal antibody which specifically reacts to basal cells

Sixty-three primary lung carcinomas were examined immunohistochemically using a monoclonal antibody, KP8D4, which reacted specifically to basal cells in the lung. Seven of ten squamous cell carcinomas, four of 41 adenocarcinomas, two of five large cell carcinomas, and one adenosquamous carcinoma were reactive with KP8D4; however, four small cell carcinomas, one mucoepidermoid carcinoma, and one carcinoid tumor were all not reactive to this antibody. Four adenocarcinomas stained by KP8D4 were Clara cell type adenocarcinomas, and two of them also revealed reactivity to surfactant apoprotein in the same cells labeled with KP8D4. These results indicate that carcinomas positive to KP8D4, including adenocarcinomas at the lung periphery, expressed phenotypically the same protein which was specifically recognized in the basal cells, suggesting that the basal cells possessing a multipotent capability of differentiation are a possible candidate of progenitor cells of lung carcinomas, including peripheral type lung carcinomas.