AM 112.indd

cd200/cd200R are highly conserved type i paired membrane glycoproteins that belong to the ig superfam‐ ily containing a two immunoglobulin ‐like domain (v, c). cd200 is broadly distributed in a variety of cell types, whereas CD200R is primarily expressed in myeloid and lymphoid cells. They fulfill multiple functions in regulating inflamma‐ tion. the interaction between cd200/cd200R results in activation of the intracellular inhibitory pathway with Rasgap recruitment and thus contributes to effector cell inhibition. It was confirmed that the CD200R activation stimulates the dif‐ ferentiation of t cells to the treg subset, upregulates indoleamine 2,3 ‐dioxygenase activity, modulates cytokine environment from a Th1 to a Th2 pattern, and facilitates an antiinflammatory IL ‐10 and TGF ‐β synthesis. CD200/CD200R are required for maintaining self ‐tolerance. Many studies have demonstrated the importance of cd200 in controlling autoimmunity, inflammation, the development and spread of cancer, hypersensitivity, and spontaneous fetal loss.