Signal Inhibitory Receptor on Leukocytes-1 (SIRL-1) is expressed on human blood monocytes and granulocytes and inhibits myeloid effector functions. On monocytes, but not granulocytes, SIRL-1 expression is low or absent in individuals with the single nucleotide polymorphism (SNP) rs612529C. The expression of SIRL-1 in tissue and the influence of rs612529 hereon is currently unknown. Here, we used flow cytometry to determine SIRL-1 expression on immune cells in human blood and three barrier tissues; skin, colon and lung. SIRL-1 was expressed by virtually all neutrophils and eosinophils in these tissues. In contrast, SIRL-1 was not expressed by monocyte-derived cells in skin and colon, whereas it was highly expressed by lung classical monocytes. Lung monocytes from individuals with a rs612529C allele had decreased SIRL-1 expression, consistent with the genotype association in blood. Within the different monocyte subsets in blood and lung, SIRL-1 expression was highest in classical monocytes and lowest in nonclassical monocytes. SIRL-1 was not expressed by dendritic cells in blood and barrier tissues. Together, these results indicate that SIRL-1 is differentially expressed on phagocyte subsets in blood and barrier tissues, and that its expression on monocytes is genotype- and tissue-specific. Immune regulation of monocytes by SIRL-1 may be of particular importance in the lung.

白细胞-1上的信号抑制受体（SIRL-1）在人血液单核细胞和粒细胞上表达，并抑制髓样效应子功能。在单核细胞而非粒细胞上，具有单核苷酸多态性（SNP）rs612529C的个体中的SIRL-1表达较低或不存在。目前尚不清楚SIRL-1在组织中的表达及其对rs612529的影响。在这里，我们使用流式细胞仪来确定人血和三个屏障组织中免疫细胞上的SIRL-1表达。皮肤，结肠和肺。在这些组织中，几乎所有嗜中性粒细胞和嗜酸性粒细胞都表达了SIRL-1。相反，SIRL-1在皮肤和结肠中不由单核细胞衍生的细胞表达，而在肺经典单核细胞中则高表达。来自具有rs612529C等位基因的个体的肺单核细胞的SIRL-1表达降低，与血液中的基因型关联一致。在血液和肺的不同单核细胞子集中，SIRL-1表达在经典单核细胞中最高，在非经典单核细胞中最低。血液和屏障组织中的树突状细胞未表达SIRL-1。总之，这些结果表明SIRL-1在血液和屏障组织中的吞噬细胞亚群上差异表达，并且其在单核细胞上的表达是基因型和组织特异性的。SIRL-1对单核细胞的免疫调节在肺中可能特别重要。这些结果表明，SIRL-1在血液和屏障组织中的吞噬细胞亚群上差异表达，并且其在单核细胞上的表达是基因型和组织特异性的。SIRL-1对单核细胞的免疫调节在肺中可能特别重要。这些结果表明，SIRL-1在血液和屏障组织中的吞噬细胞亚群上差异表达，并且其在单核细胞上的表达是基因型和组织特异性的。SIRL-1对单核细胞的免疫调节在肺中可能特别重要。