The LAIR-1 receptor is expressed on a majority of mononuclear leukocytes. It is used as a biomarker when testing synovial fluid for evidence of rheumatoid arthritis (RA). The primary objective of this study was to measure T cell- and monocyte/macrophage-specific LAIR-1 expression in RA patients and compare this to LAIR-1 expression in osteoarthritis (OA) patients and healthy individuals. LAIR-1 expression was significantly decreased in circulating CD4(+) T cells in RA patients compared to both OA patients and healthy individuals. In contrast, LAIR-1 is high in CD14(+) monocytes and local CD68(+) macrophages in synovial tissues from RA patients. Upon stimulation with TNF-α, LAIR-1 expression decreased in T-helper (Th)1 and Th2 CD4(+) T cells from healthy donors. These results indicate that LAIR-1 may exert different functions on T cells and monocytes/macrophages and suggest that LAIR-1 may be a novel therapeutic target for the treatment of RA.
Keywords: LAIR-1; Monocytes/macrophages; Rheumatoid arthritis; T cells.
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