CD83, a member of the immunoglobulin (Ig) superfamily, is expressed in membrane-bound (mCD83) and soluble (sCD83) forms. It is expressed on mature dendritic cells (DCs), activated B cells, T cells, and numerous other activated immune cells. CD83 is not just a co-stimulatory molecule but is crucial in controlling and resolving immune responses, and is involved in the differentiation of T and B lymphocytes as well as the development and maintenance of tolerance [1,2].

In the context of immune thrombocytopenia (ITP), CD83 plays an important role in its pathogenesis. ITP patients show higher CD83 expression than healthy controls. Down-regulation of DC-CD83 inhibits CD4+ T cell proliferation, while over-expression promotes it. siRNA-CD83 can reverse Th1/Th2 and Th17/Tregs polarization, inhibit pro-inflammatory cytokine secretion, and increase regulatory cytokine concentrations [3]. In experimental autoimmune uveitis (EAU), CD83+ B cells, the main sources of sCD83, alleviate symptoms by inhibiting DCs through sCD83. sCD83 interacts with Rab1a in DCs to inhibit mTORC1 phosphorylation and NLRP3 expression [4].

In summary, CD83 is a key regulatory molecule in the immune system. Its functions in diseases like ITP and EAU highlight its importance in immunological balance. Although no gene knockout (KO) or conditional knockout (CKO) mouse models were mentioned in the provided references, the existing studies suggest that understanding CD83 may provide new therapeutic strategies for autoimmune and hematological diseases.

References:

1. Riaz, Bushra, Islam, S M Shamsul, Ryu, Hye Myung, Sohn, Seonghyang. 2023. CD83 Regulates the Immune Responses in Inflammatory Disorders. In International journal of molecular sciences, 24, . doi:10.3390/ijms24032831. https://pubmed.ncbi.nlm.nih.gov/36769151/

2. Grosche, Linda, Knippertz, Ilka, König, Christina, Steinkasserer, Alexander, Lechmann, Matthias. 2020. The CD83 Molecule - An Important Immune Checkpoint. In Frontiers in immunology, 11, 721. doi:10.3389/fimmu.2020.00721. https://pubmed.ncbi.nlm.nih.gov/32362900/

3. Wang, Xiuli, Zhou, Qiyuan, Yang, Wen, Zhou, Yongchun, Zhou, Zeping. 2024. The role of CD83 in the pathogenesis of immune thrombocytopenia. In Hematology (Amsterdam, Netherlands), 29, 2372482. doi:10.1080/16078454.2024.2372482. https://pubmed.ncbi.nlm.nih.gov/38994874/

4. Feng, Meng, Wang, Xin, Zhou, Shuping, Wei, Xunbin, Lin, Wei. 2023. CD83+ B cells alleviate uveitis through inhibiting DCs by sCD83. In Immunology, 170, 134-153. doi:10.1111/imm.13654. https://pubmed.ncbi.nlm.nih.gov/37137669/