The activity of pulmonary lymphocytes was evaluated by the detection of interleukin-2 (IL-2) receptor alpha mRNA expression in lung cancer patients associated with diffuse interstitial shadow on roentgenograms of their lungs. Reverse transcription coupled with the polymerase chain reaction was used to detect mRNA expression. In 5 of 6 patients, IL-2R alpha mRNA expression was increased in pulmonary lymphocytes compared with 4 normal controls. The expression in this mRNA in peripheral blood lymphocytes was almost undetectable in either normal controls or these patients. These results suggest that pulmonary lymphocytes in patients with lung cancer associated with diffuse interstitial shadows are activated and may promote the inflammatory process generating pulmonary fibrosis
