Department of Microbiology, Columbia University, New York, NY, USA.
J Lipid Res. 2011 Aug;52(8):1542-50. doi: 10.1194/jlr.M015412. Epub 2011 May 13.
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.
清道夫受体（ScRs）是一组结构上无相关性的受体家族，能够结合修饰的低密度脂蛋白（LDL）以及广泛的多阴离子配体。CD68 是清道夫受体家族的独特成员，其表达仅限于单核吞噬细胞，这归因于其溶酶体相关膜蛋白（LAMP）样结构域和主要的内体分布。通过敲除（ko）小鼠来直接评估小鼠 CD68 在氧化型 LDL（Ox-LDL）摄取中可能发挥的作用。然而，CD68⁻/⁻巨噬细胞能够强烈摄取 Ox-LDL。同样，在摄取或对多种微生物产生有效先天免疫反应的能力方面，也未观察到 CD68⁻/⁻单核吞噬细胞的缺陷。奇怪的是，CD68⁻/⁻单核吞噬细胞表现出增强的向 CD4⁺T 细胞呈递抗原的趋势，这表明 CD68 可能通过负调节抗原摄取、加载或主要组织相容性复合体 II（MHC-II）转运来发挥作用。
