Deletion of the murine scavenger receptor CD68

Scavenger receptors (ScRs) are a structurally unrelated family of receptors with the ability to bind modified low density lipoprotein (LDL) as well as a broad range of polyanionic ligands. CD68, whose expression is restricted to mononuclear phagocytes, is a unique ScR family member, owing to its lysosome associated membrane protein (LAMP)like domain and predominant endosomal distribution. Knockout (ko) mice were generated to directly evaluate the role murine CD68 may play in oxidized LDL (Ox-LDL) uptake. However, CD68(-/-) macrophages took up Ox-LDL robustly. Likewise, no defects were observed in the ability of CD68(-/-) mononuclear phagocytes to take up or mount an effective innate response against a number of microbes. Curiously, CD68(-/-) mononuclear phagocytes exhibited a trend toward enhanced antigen presentation to CD4+ T-cells, raising the possibility that CD68 may function either to negatively regulate antigen uptake, loading, or major histocompatibility complex class II (MHC-II) trafficking.-Song, L., C. Lee, and C. Schindler. Deletion of the murine scavenger receptor CD68. J. Lipid Res. 2011. 52: 1542-1550.