TNF and infection: iNOS is not present in resting cells but can be induced by immunostimulatory type 1 cytokines, such as interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), and interleukin-1 (IL-1), but also by microbial cell wall components, such as lipopolysaccharide (LPS) and lipoteichoic acid (LTA), during an infection (5).