Yang D, Chen Q, Le Y, Wang J M, Oppenheim J J
Laboratory of Molecular Immunoregulation, Division of Basic Sciences, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA.
J Immunol. 2001 Mar 15;166(6):4092-8. doi: 10.4049/jimmunol.166.6.4092.
Monocytes are the common precursors for myeloid dendritic cells (DC) and macrophages. Identification of chemotactic receptors expressed by myeloid DC, macrophages, and their precursors in the course of differentiation and maturation is important not only for elucidation of their in vivo trafficking, but also for understanding of the functional distinction between DC and macrophages. We chose to study formyl peptide receptor like-1 (FPRL1), a chemotactic receptor known to interact with several endogenous agonists that are involved in inflammatory and host defense responses. Here we show that FPRL1 is down-regulated as monocytes differentiate into DC. This down-regulation occurs at both mRNA and functional levels. Therefore, the interaction of FPRL1 with its agonists is more likely to regulate the in vivo trafficking of DC precursors than DC. In contrast, FPRL1 expression is maintained at both mRNA and functional levels as monocytes differentiate into macrophages. Thus, our results demonstrate further distinctions between myeloid DC and macrophages, albeit they share a common precursor. The fact that macrophages rather than myeloid DC express functional FPRL1 suggests that this chemotactic receptor may be more involved in inflammatory reactions and innate host defense than in adaptive immune responses.
单核细胞是髓样树突状细胞（DC）和巨噬细胞的共同前体。鉴定髓样DC、巨噬细胞及其前体在分化和成熟过程中表达的趋化受体，不仅对于阐明它们在体内的迁移很重要，而且对于理解DC和巨噬细胞之间的功能差异也很重要。我们选择研究类甲酰肽受体1（FPRL1），这是一种已知与多种参与炎症和宿主防御反应的内源性激动剂相互作用的趋化受体。在此我们表明，随着单核细胞分化为DC，FPRL1表达下调。这种下调在mRNA和功能水平均会发生。因此，FPRL1与其激动剂的相互作用更有可能调节DC前体而非DC在体内的迁移。相反，随着单核细胞分化为巨噬细胞，FPRL1在mRNA和功能水平均保持表达。因此，我们的结果进一步证明了髓样DC和巨噬细胞之间的差异，尽管它们有共同的前体。巨噬细胞而非髓样DC表达功能性FPRL1这一事实表明，这种趋化受体可能更多地参与炎症反应和先天性宿主防御，而非适应性免疫反应。
