Deficient immune interferon production in tuberculosis

Production of interferon (IFN)-alpha and -gamma by peripheral blood mononuclear cells (PBMC) were studied in 28 patients with active tuberculosis and 28 healthy control subjects matched for age, sex, ethnic origin and diet. No significant differences were found between patients and matched controls in mean titres of IFN-alpha induced by Newcastle disease virus, IFN-gamma induced by staphylococcal enterotoxin A with tetrahydrophorbyl acetate, and IFN-gamma induced by purified protein derivative (PPD). However, a subset of nine out of 25 tuberculosis patients tested produced low titres (less than 100 u/ml) of IFN-gamma in response to PBMC stimulation with PPD. In comparison to other patients, this group was characterized by lower IFN-alpha and IFN-gamma responses to virus and mitogens respectively, relative anergy to tuberculin skin testing, depressed in vitro PBMC proliferative responses to PPD, and neutrophil leucocytosis. In all nine patients effective chemotherapy restored cutaneous reactivity, PBMC proliferative responses, neutrophil counts and IFN-alpha responses to virus by 6 months, and also IFN-gamma responses to PPD in one patient re-tested.