Immunohistochemical analysis of human adenocarcinomas of the lung using the monoclonal antibody 44-3A6.

In this study, 39 primary, surgically resected, pulmonary adenocarcinomas of the following cell types were investigated: 19 Clara cell, 4 bronchial-gland, 15 goblet cell, and 1 type II alveolar epithelial adenocarcinoma. They were analyzed for the expression of the glandular differentiation-associated antigen recognized by the monoclonal antibody 44-3A6. Formalin-fixed, paraffin-embedded tissue sections were immunostained using the avidinbiotin complex/peroxidase method. All of the Clara cell tumors (19/19) expressed this antigen as well as 3/4 bronchial-gland tumors, as compared to only 2/15 goblet cell tumors. The single type II pneumocyte neoplasm studied was found to express this antigen. These findings parallel our earlier observations based on cytological features, and provide supportive evidence that there may be biological differences between human pulmonary adenocarcinomas and bronchioloalveolar carcinomas.