Variations in LTA4H levels or activity, represented by the rheostat symbol, influence the balance between pro-inflammatory LTB4 and anti-inflammatory LXA4. High levels of LXA4 inhibit TNF production, resulting in exuberant intracellular bacterial growth, increased granuloma formation, increased macrophage death and the cording morphology typical of extracellular mycobacteria. Although WT levels of TNF are protective during infection, excessive levels of TNF may produce increased immunopathology, resulting in worse outcome from mycobacterial infections.