Increased circulating activated T-cells in lung cancer

T-cell activation (Tac) antigens, which are closely associated with the receptors for interleukin 2 (IL 2) and expressed on activated human T-lymphocytes, are found on a small percentage of normal peripheral T-cells. Elevated levels of Tac antigen-positive (Tac+) cells were observed in a high proportion of patients with untreated primary lung cancer assessed by using monoclonal anti-Tac antibody. The mean percentage of Tac+ cells in peripheral blood lymphocytes was 13.1 +/- 6.4 percent in patients with primary lung cancer (n = 67), as compared with 4.3 +/- 1.9 percent in normal controls (n = 30) (p less than 0.001). No significant differences were observed among the cell types of lung cancer examined (adenocarcinoma and squamous and small cell carcinoma). The stages of the disease also showed no significant differences in the development of Tac+ cells. Our results suggest that T-cell-mediated active immune mechanisms against malignant cancer cells are operative in patients with lung cancer, resulting in an increase in activated T-cells in the peripheral blood, although it remains to be elucidated whether these activated T-cells exert a favorable or unfavorable effect on their host.