Scavenger receptor class B type I and immune dysfunctions.

PURPOSE OF REVIEW:To summarize the recent findings about the roles of scavenger receptor class B type I (SR-BI) in immunity and discuss the underlying mechanisms by which SR-BI prevents immune dysfunctions. RECENT FINDINGS:SR-BI is well known as a high-density lipoprotein (HDL) receptor playing key roles in HDL metabolism and in protection against atherosclerosis. Recent studies have indicated that SR-BI is also an essential modulator in immunity. SR-BI deficiency in mice causes immune dysfunctions, including increased atherosclerosis, elevated susceptibility to sepsis, impaired lymphocyte homeostasis, and autoimmune disorders. SR-BI exerts its protective roles through a variety of HDL-dependent and HDL-independent mechanisms. SR-BI is also involved in hepatitis C virus cell entry. A deficiency of SR-BI in humanized mice has been shown to decrease hepatitis C virus infectivity. SUMMARY:SR-BI regulates immunity via multiple mechanisms and its deficiency causes numerous diseases. A comprehensive understanding of the roles of SR-BI in protection against immune dysfunctions may provide a therapeutic target for intervention against its associated diseases.