Abstract: Objective To investigate the expression of CD200/CD200R1 in the PBMC of primary immune thrombocytopenia patients and its clinical significance. Methods The mRNA relative expression of CD200/CD200R1 in ITP patients (n=19) and healthy controls (n=19) were measured by RT-PCR. Then we determined the protein levels of TNF-α, IFN-γ and IL-17 in plasma. We further analyzed the correlation between CD200/CD200R1 expression and platelet counts. The changes of CD200/CD200R1 after effective treatment were also be tested by RT-PCR. Results Compared to healthy controls, CD200/CD200R1 were decreased in ITP patients. TNF-α, IFN-γ and IL-17 protein expressions were increased compared with healthy controls. TNF-α and IFN-γ were negatively correlated with CD200/CD200R1, and the platelet counts in ITP patients were positively correlated with CD200/CD200R1. Moreover, after effective treatment by dexamethasone, the mRNA expression of CD200/CD200R1 showed an obviously increase trend. Conclusion CD200/CD200R1 may be involved in the pathogenesis of ITP and related to the decreased inhibition effect of inflammatory cytokines expression, which provides a new cluefor future immunotherapy.

Key words: Primary immune thrombocytopenia, CD200/CD200R1, Cytokines