中文摘要：

目的探讨共刺激分子PD-L2在牛二型胶原（CII）诱导的类风湿关节炎模型小鼠免疫器官、关节及RA患者滑膜组织内的表达。方法使用牛二型胶原免疫DBA-1/j小鼠,建立小鼠类风湿关节炎模型;免疫组化检测类风湿关节炎标本PD-L2的表达变化;双色免疫荧光分析PD-L2的细胞学定位。结果免疫组化的结果证实,小鼠的骨髓、胸腺、脾脏及淋巴结有中有大量的PD-L2阳性细胞,免疫荧光分析结果表明这些PD-L2＋细胞主要为CD68＋巨噬细胞及CD31＋内皮细胞。但PD-L2表达及分布在CIA小鼠内并没有显著提高。此外RA患者及CIA小鼠的滑膜组织内发现大量PD-L2阳性的细胞。结论 PD-L2高表达于CIA模型小鼠关节滑膜组织内的抗原递呈细胞（包括巨噬细胞及内皮细胞）表面,提示其有可能通过调节浸润于滑膜组织内的T细胞的功能状态并最终调节了关节炎的病理进程。

英文摘要：

To investigate the role of PD-L2 in regulating the development of rheumatoid arthritis（RA）,we detected PD-L2 protein expression in tissues from bovine collagen II（CII）-induced mouse rheumatoid arthritis（CIA） and synovial tissues of RA patients.We firstly analyzed the expression and distribution of PD-L2 protein by immunohistochemistry.Moreover,fluorescence double-staining was used to further characterize PD-L2 expression.Immunohistochemical analysis revealed that PD-L2 positive cells were distributed in thymus,spleen,lymph nodes,and bone marrow,while double staining further demonstrated that PD-L2 positive cells were mainly in CD68＋ and CD31＋ cells.However,the expression and distribution of PD-L2 did not show significant difference between normal and CIA mice.Interestingly,high level of PD-L2 positive cells was found both in synovial tissues of CIA mice and RA patients.In this study,expression of PD-L2 was observed on the surface of antigen presentation cells including macrophages and endothelial cells within immune organs and synovial tissues of CIA mice and RA patients,which indicates that this signal might be involved in regulating local T cell activation and finally participated in the pathogenesis of RA.