To examine whether the observed PM-mediated suppression of M. tb-induced IFN-γ and IL-β-production by PBMC is associated with alterations in the control of M. tb growth in PBMC, we exposed PBMC from IGRA- and IGRA+ subjects to PM2.5 and PM10 (0, 1 and 5 μg/ml) from the three seasons followed by infection with M. tb at MOI 1. This evidence concerns the gene IFNG and infection.