NFATp and TB Infection Figure 4. Correlation of serum TNF protein levels with MTb disease progression in WT and NFATp2/2 mice. WT and NFATp2/2 mice were infected with the aerosolized clinical MTb strain HN878 at ,100 CFU/mouse as described [50]. Four random mice were bled at four-week intervals after initial infection and serum levels of TNF were measured by ELISA. doi:10.1371/journal.pone.0041427.g004 reduced TNF expression in Th1 cells and, more dramatically, in Th2 cells. Taken together, these experiments correlate impairment of T cell production of IFN-c and TNF with the increased observed susceptibility of NFATp2/2 mice to TB. Moreover, they demonstrate that production of TNF from the DC compartment of NFATp2/2 mice in response to TB stimulation is not impaired and thus suggest that DC are a major source of NFATp- independent TNF transcription in this model. These experiments led us to next investigate whether the timing of TNF production in both the NFATp2/2 and WT mice was functionally important in the immune control of TB infection in these mice and/or the observed high TNF levels in lung and peripheral blood in the NFATp2/2 mice infected with TB were simply a marker of increased disease and earlier activation of DC or other monocytic cells where expression of TNF is not dependent upon NFATp. Early blocking of total TNF signaling post-MTb infection leads to higher mortality in WT and NFATp2/2 mice. To examine whether a further reduction in TNF levels by blocking TNF production in NFATp2/2 mice affected the mortality of these mice, we infected NFATp2/2 mice and age-matched WT mice with aerosolized HN878 in the presence or absence of the PLoS ONE | www.plosone.org 6 July 2012 | Volume 7 | Issue 7 | e41427