ABSTRACT
<p><b>OBJECTIVE</b>To investigate the changes in peripheral blood Th17 and CD4(+)CD25(+) regulatory T (Treg) cells and their significance among children with hand, foot and mouth disease (HFMD).</p><p><b>METHODS</b>Eighty-nine children with HFMD, including 55 cases of common HFMD and 34 cases of severe HFMD, were included in the study; and 30 healthy children were selected as the control group. The percentages of Th17 and CD4(+)CD25(+) Treg cells in CD4(+) T cells in peripheral blood were determined by flow cytometry. The expression levels of interleukin (IL)-10, transforming growth factor-β (TGF-β), and IL-17 were measured by enzyme-linked immunosorbent assay.</p><p><b>RESULTS</b>Compared with the control group, the cases of common HFMD and severe HFMD had significantly increased levels of Th17 cells and IL-17 (P<0.05) but significantly decreased levels of CD4(+)CD25(+) Treg cells, IL-10, and TGF-β (P<0.05). The severity of the HFMD was positively correlated with the levels of Th17 cells and IL-17 in peripheral blood but negatively correlated with the levels of CD4(+)CD25(+) Treg cells, IL-10, and TGF-β.</p><p><b>CONCLUSIONS</b>Children with HFMD have increased response of Th17 cells but decreased response of CD4(+)CD25(+) Treg cells in peripheral blood. Th17/CD4(+)CD25(+) Treg cell imbalance may play an important role in the pathogenesis of HFMD.</p>