Expression Of Fcgamma Receptors And Its Regulation By Dexamethasone In Childhood Acute Immune Thrombocytopenia

Objective:To examine the changes of expression activating Fcgammareceptors(FcγRⅠ/CD64, FcγRⅢ/CD16) and the mRNA expression of FcγRⅡaand FcγRⅡb on monocytes, as well as the serum concentration of interferon-γ、interleukin-4and interleukin-10in newly diagnosed childhood acute immunethrombocytopenia before and after dexamethasone treatment and healthycontrols; The posible effect of dexamethasone treatment on expression ofactivating and inhibitory FcγRs on monocytes were explored.Methods:27childhood patients with aITP and25health controls were enrolled in thisstudy. The expression FcγRⅠand FcγRⅢ on monocytes surface weredetermined by flow cytometry, Real-time PCR was performed to detect themRNA expression of activating FcγRⅡa and inhibitory FcγRⅡb on monocytes,The plasma concentrations of interleukin-4、interleukin-10and interferon-γ wereanalyzed by ELISA.Results: ①The levels of FcγRⅠ and FcγRⅢ expression on monocytes weresignificantly higher in ITP patients than those in health control group.②Transcription levels of FcγRⅡa mRNA and the ratio of FcRIIa/IIbmRNA on monocytes were significantly elevated, while the inhibitory FcγRⅡbmRNA was significant lower in ITP patients，in comparison with healthycontrols. After dexamethasone treatment, the stimulatory FcγRⅠ，FcγRⅢ andFcγRⅡa mRNA were significantly decreased while inhibitory FcγRⅡb mRNAwas increased.③The higher levels of plasma IFN-γ and lower Il-4were to be found in ITPpatients compared with healthy controls.④Correlation analysis showed that the level of plasma IFN-γ waspositively correlated with the elevated expression of FcγRⅡa mRNA onmonocytes, while the level of IL-4was positively correlated with FcγRⅡbmRNA.Conclusion:The over-expression of inhibitory FcγRs and the down-regulation ofinhibitory FcγRⅡb mRNA on monocytes, and the imbalance of stimulatory andinhibitory FcγR might be involved in immunological pathogenesis of the acuteITP. The alteration levels of plasma pro-inflammatory cytokine IFN-γ andanti-inflammatory cytokine IL-4might be related to imbalance expression ofFcγR in acute ITP. Dexamethasone therapy could improve the balance between stimulatory and inhibitory FcγR in acute ITP patients.