CD84 (SLAMF5) is a member of the SLAM family of cell-surface immunoreceptors. Broadly expressed on most immune cell subsets, CD84 functions as a homophilic adhesion molecule, whose signaling can activate or inhibit leukocyte function depending on the cell type and its stage of activation or differentiation. CD84-mediated signaling regulates diverse immunological processes, including T cell cytokine secretion, natural killer cell cytotoxicity, monocyte activation, autophagy, cognate T:B interactions, and B cell tolerance at the germinal center checkpoint. Recently, alterations in CD84 have been related to autoimmune and lymphoproliferative disorders. Specific allelic variations in CD84 are associated with autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis. In chronic lymphocytic leukemia, CD84 mediates intrinsic and stroma-induced survival of malignant cells. In this review, we describe our current understanding of the structure and function of CD84 and its potential role as a therapeutic target and biomarker in inflammatory autoimmune disorders and cancer.

CD84（SLAMF5）是SLAM家族的细胞表面免疫受体的成员。CD84在大多数免疫细胞亚群上广泛表达，其功能是同型粘附分子，其信号传导可激活或抑制白细胞功能，具体取决于细胞类型及其激活或分化的阶段。CD84介导的信号传导调节各种免疫学过程，包括T细胞细胞因子分泌，自然杀伤细胞的细胞毒性，单核细胞激活，自噬，同源T：B相互作用以及生发中心检查站的B细胞耐受性。最近，CD84的改变与自身免疫和淋巴增生性疾病有关。CD84中的特定等位基因变异与自身免疫性疾病有关，例如系统性红斑狼疮和类风湿关节炎。在慢性淋巴细胞性白血病中，CD84介导内在的和基质诱导的恶性细胞存活。在这篇综述中，我们描述了我们目前对CD84的结构和功能及其在炎性自身免疫性疾病和癌症中作为治疗靶标和生物标志物的潜在作用的理解。