NOS2 and infection: Nos2 mRNA expression was complemented by an increase in nitrite production in IL-4i1−/− BMDMs at 3 days after infection, which was correlated with a decreasing trend in intracellular Mtb growth) and a significant increase in interleukin 12p40 (IL-12p40), interleukin 1β (IL-1β), and tumor necrosis factor (TNF) levels (Figure 1C).