Expression of Das-1 in primary lung adenocarcinomas represents reactivation of an oncofetal pulmonary antigen

Objective: The monoclonal antibody (mAb) designated as mAb Das-1 was generated against a colonic epithelial protein. It reacts with bronchiolar epithelium and submucosal glands and weakly with alveolar lining cells of fetal lung. Adult alveolar epithelium is, however, nonreactive for mAb Das-1. The present study was designed to evaluate the immunoexpression of Das-1 and to correlate it with the histomorphology of primary lung adenocarcinomas and intestinal metaplasia. Methods: Eighty-four cases of primary lung adenocarcinomas were reviewed and categorized according to histologic grade and subtype. Immunohistochemical staining with mAb Das-1 was performed with normal colon as control. Results: Expression of Das-1 in the submucosal bronchial glands also served as internal control. Strong and diffuse staining was seen in 33 of the 84 cases of adenocarcinomas (39%). Conclusions: Expression of Das-1 was seen in primary lung adenocarcinomas even though adult alveolar epithelium is negative. Staining with mAb Das-1 was seen regardless of the grade or histological subtype of the lung adenocarcinomas. As most primary lung adenocarcinomas are not of bronchial gland origin, expression of Das-1 represents activation of oncofetal antigens.