Natural killer cell activity in tuberculosis

Natural killer (NK) cell activity was studied in 27 patients with active tuberculosis and 27 healthy controls matched for age, sex, ethnic origin and diet. Spontaneous and interferon (IFN)-augmented NK cytotoxicity against K562 target cells were measured, using a 4-hour 51Cr-release assay. There were no differences between the patients and their matched controls in mean spontaneous and IFN-augmented cytotoxicity before and during antituberculosis chemotherapy. However, one malnourished alcoholic patient with extensive non-reactive multibacillary disease had depressed NK cell activity which was not significantly enhanced by in vitro pretreatment with leucocyte IFN. We conclude that the NK system is not of prime importance in host defence against human tuberculosis, although advanced disease may be associated with deficient NK activity, as part of generalized anergy.