Lipid Droplets as Immune Modulators in Myeloid Cells

Lipid droplets (LDs) were initially described as fat storage organelles in adipocytes, but are increasingly recognized as dynamic players in lipid metabolism, with important roles not only in diseases such as diabetes and cancer, but also in immune regulation. Alterations in immune cell function, such as myeloid cell activation, are connected to profound changes in LD numbers and LD protein composition. Thus, these organelles appear to be essential to metabolically support immune responses, and have a vital role in antigen crosspresentation, interferon (IFN) responses, production of inflammatory mediators, and pathogen clearance. Here, we review recent studies that report on the role of LDs in the modulation of immune cell function, primarily focusing on myeloid cells, such as macrophages and dendritic cells (DCs).