Study On The Quantity And Function Of T Follicular Helper Cells In The Bone Marrow Of Immune Thrombocytopenia Patients

Objective To study the quantity and function of bone marrow (BM) T follicular helper (Tfh) cells of immune thrombocytopenia patients, and explore the role of Tfh cells in the pathogenesis of ITP.Methods Twenty-one untreated ITP patients, twenty recovered ITP patients and eighteen normal controls were enrolled in this study. The percentages of CD4+CXCR5+/CD4+cells, CD4+CXCR5+ICOS+/CD4+CXCR5+cells, CD4+CXCR5+CD40L+/CD4+CXCR5+cells, intracytoplasm CD4+CXCR5+IL-21+/CD4+CXCR5+cells were investigated by flow cytometry (FCM), and the expressions of Bcl-6mRNA in BMMNC by semiquantitive RT-PCR. Correlation of Tfh cells frequency in BM and clinical evidence in ITP patients.Results1. The ratio of CD4+CXCR5+/CD4+cells of untreated ITP patients [(5.532±2.599)%] was significantly higher than that of recovered ITP patients [(4.064±2.026)%] and controls[(4.048±1.413)%](P<0.05).2. The ratio of CD4+CXCR5+ICOS+/CD4+CXCR5+cells of untreated ITP patients [(14.586±8.561)%] was higher than that of recovered ITP patients [(12.884±10.161)%] and controls [(7.487±5.176)%]. The differences between untreated ITP patients and controls were significant (P<0.05).3. The ratio of CD4+CXCR5+CD40L+/CD4+CXCR5+cells of untreated ITP patients [(15.309±10.756)%] and recovered ITP patients [(18.242±12.243)%] were significantly higher than that of controls [(8.618±5.719)%](P<0.05).4. The ratio of intracytoplasm CD4+CXCR5+IL-21+/CD4+CXCR5+cells of untreated ITP patients [(58.560±26.285)%]and recovered ITP patients[(57.035±30.936)%] were significantly higher than that of controls [(36.289±24.868)%](P<0.05).5. The relative expressions of Bcl-6mRNA in BMMNC were (1.407±0.264),(1.149±0.217) and (0.846±0.157) in three groups, respectively. The differences between untreated ITP patients, recovered ITP patients and controls were significant(P<0.05).6.There were significantly positive correlation between the ratio of CD4+CXCR5+ /CD4+and the expression of Bcl-6mRNA, the number of platelets, the level of serum IgA, the ratio of CD3+CD4+/CD3+CD8+(r=0.395,-0.362,0.504,0.491, respectively, P<0.05). There was significantly positive correlations between the ratio of CD4+CXCR5+/CD4+and the number of megakaryocytes which do not produce platelets(r=0.416, P<0.05). There was significantly positive correlation between the ratio of CD4+CXCR5+ICOS+/CD4+CXCR5+and CD5+CD197CD19+(r=0.365, P<0.05).Conclusions:There exists increased quantity and hyperfunction of Tfh cells in the ITP patients, they may play important role in the pathogenesis of ITP. The ratio of Tfh cell may be closely related to the severity of ITP disease. Tfh cells and their effector molecules such as CD40L, IL-21and ICOS may be regarded as potential new therapeutic targets of ITP...