Cd83, a member of the immunoglobulin (Ig) superfamily, is expressed in membrane-bound or soluble forms. It is highly expressed by mature dendritic cells (DCs), and also on activated B cells and T cells. Cd83 is involved in regulating the immune responses, playing a role in monitoring and resolving inflammatory reactions, as well as in lymphocyte maturation, activation and homeostasis [1,2,3,7].

In immune thrombocytopenia (ITP), ITP patients showed higher CD83 expression than healthy controls. Down-regulation of DC-CD83 inhibited CD4+ T cell proliferation, while over-expression promoted it. siRNA-CD83 regulated cytokine secretion and Tregs expression, reversing Th1/Th2 and Th17/Tregs polarization, indicating its important role in ITP pathogenesis [4].

In experimental autoimmune uveitis (EAU), CD83+ B cells, the main sources of sCD83, alleviated EAU symptoms by decreasing T cells and DCs in the eyes and lymph nodes, and by inhibiting DCs through sCD83 [5]. Also, sCD83 modulates human-monocyte-derived macrophages toward an alternative phenotype, function, and metabolism, increasing the expression of inhibitory molecules and down-regulating pro-inflammatory pathways [6].

In conclusion, Cd83 is crucial for immune regulation. Findings from various disease-related studies, such as in ITP and EAU, demonstrate its role in modulating immune responses and cell functions. These insights help understand the underlying immunological mechanisms and may provide potential therapeutic strategies for related diseases.