Enhanced natural killer cell activity in patients with pulmonary tuberculosis

The natural killer (NK) cell activity of patients with pulmonary tuberculosis (TB) was studied using blood samples. The patients with pulmonary TB showed higher NK activity to 10 out of 12 NK-sensitive target cell lines than healthy subjects did. When NK activity was compared between active and inactive stages of the disease, the patients with active TB demonstrated higher NK activity than did patients with inactive TB. Furthermore, active patient displayed cytolysis to one out of 4 NK-resistant target cell lines. In study of NK cell cyotoxicity at single cell level, higher killing activity than binding activity to target cells was observed in patients at an active stage. Morphological and surface marker analysis of peripheral mononuclear cells showed an increase in CD16+ cells in patients with pulmonary TB. These results suggested that NK cell activity is augmented qualitatively and quantitatively in patients with pulmonary TB.