[Immunohistochemical study of lung cancer using monoclonal antibody against human pulmonary surfactant apoprotein]

To evaluate the clinical significance of monoclonal antibody against human pulmonary surfactant apoprotein (S-AP), surgically resected lung cancer from 122 patients was studied. Paraffin embedded tissues were used for the immunohistochemical study by the avidin-biotin-peroxidase complex method. The results were as follows. 1. Adenocarcinoma showed highest immunoreactivity for S-AP compared to the other histologic types. Among subtypes of adenocarcinoma, type II alveolar epithelial type, clara cell type and mixed type of these two types were strongly positive (100%, 77.8% and 66.7% respectively). These results indicate that this antibody may be a good marker for the subtyping of adenocarcinoma. 2. There were some positive cases in other histologic types especially in peripheral type of squamous cell carcinoma. These findings suggest that this antibody was useful for the histological differentiation of lung cancer. 3. As to the immunohistochemical reactivity there was a good correlation between tissue and cytological specimens, which indicate cytological studies may be adequate for this kind of histopathological studies. 4. In our study, there were no patients with S-AP positive carcinomas other than patients with lung cancer. These results indicate that this antibody could be used for the differential diagnosis between primary and secondary lung cancer.