FIGURE 2.

Very long fatty acid chain-containing sphingolipid metabolites mediate antigen presentation during phagocytosis of microorganisms. (A,B) Recognition of microorganisms generates sphingomyelin metabolites, including ceramide, as well as their conversion to ceramide-1-phosphate and sphingosine-1-phosphate. (C) These metabolites promote phagolysosome formation. (D) V-ATPase promotes phagosome maturation by, for example, fusing with lysosomes to degrade microorganisms, and reduced pH adjusts MHC class II activity. (E,F) Following antigen loading onto MHC class II molecules, the complexes translocate to the plasma membrane for antigen presentation.