Here, we show that during tuberculosis reactivation, TNF−/− mice formed larger lesions with inflammation occupying larger areas of the lung with some evidence of necrosis compared to WT mice, an observation that corroborates previous findings by Mohan et al., 2001 and Botha and Ryffel, 2003 where a lack of proper defined granulomas in reactivating TNF−/− mice were described [10], [33]. Here, TNF is linked to tuberculosis.