Differential Impairment of Interferon-𝛾Responses inTwo Cases of Pulmonary Nontuberculous Mycobacterial Disease

Nontuberculous mycobacteria (NTMs) are weakly virulent intracellular pathogens that are common in food and water supplies.The persistent culture of these organisms in the setting of clinical infection warrants investigation of immune function. In cases ofisolated pulmonary NTM (PNTM) disease, underlying immune defects have not been clearly identified. We present two patientswith isolated PNTM infection who demonstrated differentially impaired IFN-𝛾production across a range of stimuli. These casesshow that cellular IFN-𝛾responses may be defective in a proportion of patient suffering PNTM disease and that when assessingresponses, the stimulant used in the testing is important to delineate defective cell populations. Impaired IFN-𝛾responses to IL-12+ BCG seem to be a poor prognostic indicator in PNTM disease and in these cases were not improved by adjuvant IFN-𝛾.