Lymphocyte responses of lung cancer patients to tumor-associated antigen measured by leucine incorporation.

Lymphocyte responses to lung carcinoma-associated antigens were assessed by measuring 3H-leucine incorporation in 20 lung cancer patients, 37 patients with other neoplasms, and 20 normal subjects. Antigens were prepared from 9 lung carcinomas by means of 3M KCl extraction. Fifteen of 20 lung cancer patients showed increased leucine incorporation to one or more tumor antigens, whereas only 5 of 20 normal subjects responded. Lymphocyte responses to both autologous and allogeneic tumor extracts were observed. Eighteen lung cancer patients were tested with the most reactive antigen and 13 responded. Seven of 37 patients with other neoplasms and 2 of 18 normal subjects reacted to this antigen. Significantly more lung cancer patients reacted to the tumor extract than to an extract of uninvolved lung from the same patient. The reactivity of lymphocytes from lung cancer patients clinically free of disease was significantly greater than that of patients with disseminated disease. Extraction of lung carcinomas with 3M KCl is a useful technique for solubilizing tumor-associated antigens (TAA). Antigenic activity may be followed in vitro by measuring lymphocyte 3H-leucine incorporation.