TNF and infection: To further assess the effects of persistent p55TNFR expression on p75TNFR levels and the cytokine productions during reactivation of latent M. tuberculosis infection, we compared the levels of TNF, p75TNFR, NO and IL-12p70 in the lungs of WT mice and p55∆NS mice at 90 and 300 days post-infection.