Lung Natural Killer and Interleukin-2 Activity in Lung Cancer: A Pulmonary Compartment of Augmented Natural Killer Activity Occurs in Patients with Bronchogenic Carcinoma

Studies were performed to determine if natural killer (NK) cell and interleukin-2 (IL-2) activities are increased in lungs that harbor malignancy. The NK activity (ability to lyse 51Cr-K562 cells) in bronchoalveolar lavage mononuclear cells (BAC) and washed whole blood cells (Blood) was measured in 8 patients with bronchogenic carcinoma and 8 healthy control subjects. The mean NK activity by BAC from the patients with bronchogenic carcinoma was 2.81 lytic units, and from the control subjects it was 0.19 lytic units (p < 0.001). When the data were expressed as a ratio of NK activity for BAC/Blood, the mean ratio was 0.98 in recovered bronchoalveolar lavage fluid (BAL) using 3H-thymidine uptake by IL-2 dependent T-cells. The concentration of IL-2 was expresses as units per microgram albumin and also as units multiplied by a dilution factor. The median concentration of IL-2 in BAL from the patients with bronchogenic carcinoma was 10.5 units × 10−3/μg albumin (range, 3.7 to 229), and from the healthy control subjects it was 0.37 units × 10−3/μg albumin (range 0.26 to 0.70) (p < 0.001). When IL-2 activity was expressed as total number of IL-2 units in recovered lavage fluid times a dilution factor (volume of saline used for lavage/volume of lavage fluid recovered), the median number of IL-2 units was 4.7 for the patients with bronchogenic carcinoma and 0.085 for the control subjects (p < 0.001). There was a significant association between IL-2 activity in BAL and NK activity in BAC in the 8 patients with cancer and the 8 control subjects combined (p < 0.05). These data demonstrate that NK activity in the organ that is the site of the malignancy may be under the influence of local regulatory factors. In patients with bronchogenic carcinoma, lung NK activity increases markedly both in absolute level and relative level to blood with an elevation of IL-2 level in the lung. The possibility is raised that T-lymphocytes are activated in lungs and/or airways of patients with pulmonary neoplasms, and lymphokines (such as IL-2) are released that can augment NK activity.