Dysfunction of the plasmacytoid dendritic cells induced by Enterovirus 71

Role of Plasmacytoid Dendritic Cells (pDCs) in Enterovirus-71 (EV71)-induced Hand, Foot, and Mouth Disease (HFMD) remains unclear. We investigated pDCs in severe HFMD patients infected with EV71. Flow cytometry revealed reduced pDC percentage in severe patients compared to healthy controls. In vitro, as EV71 replicated in pDCs, live cell numbers and levels of Interferon (IFN)-alpha and Interleukin (IL)-6 decreased, while IL-10 and Tumor Necrosis Factor (TNF)-alpha increased, particularly in critical ill patients. Notably, pDCs derived from critical ill patients exhibited significantly lower amplification rate and antiviral cytokine secretion compared to healthy controls. EV71 may manipulate pDC proliferation and cytokine secretion, evading the antiviral immune response, inducing cell tolerance, and promoting apoptosis. We speculate that EV71-induced inactivation of pDCs may contribute to disease deterioration.