[Role of regulatory T cells in pathogenesis of Henoch-Schonlein purpura in children].

OBJECTIVE: Henoch-Schonlein purpura (HSP) is one of the most common small vessel forms of autoimmune vasculitis in children. Immunologic derangement including humoral and cellular immunity disequilibrium and proinflammatory factors dysfunction are involved in the acute stage of HSP. Recently data revealed that regulatory T cells (Tr) play a pivotal role in preventing development of autoimmune and allergic diseases. This study aimed to explore the role of Tr cells in pathogenesis of HSP and the factors affecting development of Tr cells.

METHODS: Twenty patients with HSP and 20 age-matched healthy children were enrolled into this study. Flow cytometric (FCM) analysis was performed to detect the percentage of regulatory T cells subpopulation (including CD(4+)CD(25+) Tr, Tr1 and Th3) and helper T cells subpopulation (Th1 and Th2). Reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR were used to analyze Foxp3 expression in peripheral blood mononuclear cell (PBMC).

RESULTS: Compared with healthy control subjects, the proportions of Th2 cell in patients with HSP were significantly higher (P < 0.05), and the ratio of Th1/Th2 was remarkably decreased (P < 0.05). The proportions of three subpopulation of regulatory T cells including CD(4+)CD(25+) Tr, Tr1, Th3 in patients with HSP were all significantly lower than those of controls (P < 0.05). The mRNA expression of Foxp3 in patients with HSP showed similar tendency (P < 0.001).

CONCLUSIONS: The decrease of three subpopulations of regulatory T cells might be involved in pathogenesis of HSP and associated with the decreased expression of Foxp3 gene.