Immunity 31, 232–244 (2009)

Lipid droplets in a type of immune cell may have a key role in triggering attacks on infected and damaged cells.

Dendritic cells engulf pathogens, chop up their components and display the resulting antigens on their surfaces using the major histocompatability complex class I (MHC I) molecules. These antigens activate cytotoxic T cells, which seek and destroy infected cells.

Pierre Guermonprez at Rockefeller University in New York and his colleagues found that an enzyme residing on lipid droplet membranes is essential to this pathway. When the researchers eliminated the enzyme in mice, they found defects in the cells' lipid droplets and in their ability to display antigens through the MHC I pathway. The manipulation did not affect the MHC II pathway.