TNF and infection: Upon PM2.5 exposure, the expression of TNF-α in response to M.tb MOI 1 and 5 infection or stimulation with PPD, PHA and LPS was significantly decreased in CD3+ and CD14+ PBMC compared to CD3+ and CD14+ PBMC infected with M.tb, or stimulated with PPD, PHA or LPS alone (p < 0.05) (Figure 5A,B).