A normal adult and fetal lung antigen present at different quantitative levels in different histologic types of human lung cancer.

Rabbits were immunized with extract of either an adenocarcinoma of the lung, or one of three oat cell carcinomas of the lung. Unabsorbed and variously absorbed antisera, and various extracts, were analyzed by double and radial immunodiffusion. The adenocarcinomas-antisera identified an antigen subsequently quantitated at high concentration in seven adenocarcinomas of the lung, but a low concentration in five normal adult and four fetal lungs. Three of four epidermoid carcinomas of the lung contained the antigen at low concentration, however only trace amounts were detected in four of five oat cell carcinomas of the lung. The oat cell carcinoma-antisera failed to identify a significant antigen. Quantitatively, the above antigen appeared to distinguish adenocarcinomas and to a lesser extent epidermoid carcinomas from oat cell carcinomas of the lung, and to be consistent with the concept that oat cell carcinomas arise from a different cell type than the other lung tumors.