Fig. 2.

Mycobacterial lipids facilitate bacterial uptake into permissive macrophage populations. (A) PDIM shields wild-type mycobacteria (green) from TLR-mediated recognition of mycobacteria by the host cell. Interaction of PGL on the bacterial cell surface with surrounding host cells drives CCR2-mediated recruitment of mycobacterial permissive macrophages. These permissive macrophages phagocytose the mycobacterium, which can subsequently form a persistent infection within the host. (B) In PDIM-deficient mycobacteria (light blue), bacterial PAMPs are recognized by TLRs, leading to MyD88-dependent recruitment of iNOS-positive macrophages. These iNOS-positive macrophages phagocytose the infecting mycobacteria and rapidly clear them through iNOS-dependent RNS.