A plasma membrane antigen highly associated with oat-cell carcinoma of the lung and undetectable in normal adult tissue.

The plasma membrane antigens of an oat-cell carcinoma of the lung were studied to determine if any antigens absent from normal adult tissue could be identified. Rabbit and monkey antisera were prepared to a highly purified plasma membrane fraction of an oat-cell carcinoma of the lung. The specificities of the antisera were studied by the indirect immunofluorescence method on frozen section substrate. The rabbit antiserum, after absorption with normal lung, liver, colon and peripheral nerve homogenates and extracts, failed to react with any detectable normal adult tissue. The absorbed anti-serum did react with 7 of 7 oat-cell carcinomas of the lung, but failed to react with any of 7 adeno-carcinomas of the lung, 6 epidermoid carcinomas of the lung, 7 colon carcinomas, 8 breast carcinomas, 4 kidney carcinomas, and 1 pancreatic carcinoma. The unabsorbed monkey antiserum failed to react with any detectable normal adult tissue, and had a tumor reactivity pattern nearly identical to that of the absorbed rabbit antiserum. Thus similar results were obtained with antisera from two different species. It is concluded that oat-cell carcinomas of the lung express a plasma membrane antigen(s) undetectable in normal adult tissue and highly associated with this tumor type.