Interferon Gamma Stimulation Fails to Restrict Mycobacterium tuberculosis Growth in Human Monocyte-derived and Alveolar Macrophages

Abstract

We examined whether IFNG restricts Mycobacterium tuberculosis (Mtb) growth in human macrophages across a range of conditions and methods. We observed an IFNG-dependent enhancement of bacterial replication in MCSF-differentiated monocyte-derived macrophages (MDMs, 4.84 x 105 CFU IFNG stimulated versus 2.48 x 105 CFU untreated, P < 0.001) with four Mtb strains. Mtb replication was not restricted by IFNG treatment of alveolar macrophages. In agreement with previous studies, IFNG-stimulated murine bone marrow derived macrophages effectively restricted Mtb replication. These data suggest that Mtb resists IFNG-stimulated immunity within human macrophages with implications for distinct host species immune responses.