NK cell activity in pulmonary tuberculosis.

Natural killer (NK) cell activity, which may provide defence mechanism in the immune surveillance system, was studied in 38 patients with active pulmonary tuberculosis and 54 sex-, and age-matched healthy controls. The mean NK cell activity in patients with active pulmonary tuberculosis (58.7 +/- 26.4%) was significantly higher (P less than 0.001) than that in healthy controls (17.4 +/- 12.2%). Classifying the patients into three groups according to the state of excretion of tubercle bacilli, the mean NK cell activity in newly diagnosed patients was 43.2 +/- 20.7%, in advanced disease 59.4 +/- 30.3%, and in successfully treated patients 71.9 +/- 25.9%.