RESUMEN
<p><b>OBJECTIVE</b>To study the roles of follicular helper T (Tfh) cells and follicular regulatory T (Tfr) cells in the pathogenesis of Henoch-Schönlein purpura (HSP) in children.</p><p><b>METHODS</b>Peripheral blood samples were collected from 40 HSP children and 25 healthy controls. The percentages of Tfh and Tfr cells were measured by flow cytometry; the mRNA expression levels of Bcl-6, c-MAF, Blimp-1, and PD-1 in peripheral blood were measured by real-time polymerase chain reaction.</p><p><b>RESULTS</b>Compared with the controls, the children with HSP had significantly increased percentage of Tfh cells and Tfh/Tfr ratio but a significantly reduced percentage of Tfr cells in the peripheral blood (P<0.05). Compared with the controls, the children with HSP had significantly increased mRNA expression of Bcl-6 and c-MAF but significantly reduced mRNA expression of Blimp-1 in CD4+ T cells (P<0.05), and had significantly increased mRNA expression of PD-1 but significantly reduced mRNA expression of Blimp-1 in CD4+CD25+ regulatory T cells (P<0.05).</p><p><b>CONCLUSIONS</b>Abnormal percentages of Tfh and Tfr cells may be involved in the pathogenesis of HSP in children, and over-expression of Bcl-6, c-MAF, and PD-1 mRNA and inhibited expression of Blimp-1 mRNA may be considered as important reasons for abnormal percentages of Tfh and Tfr cells.</p>