The Changes Of Phenotype And Function Of Peripheral γδt Cells In Children With Hand,Foot,and Mouth Disease And Its Clinical Significance

Background:Hand,foot,and mouth disease(HFMD)is a common infectious disease in children,and functional changes of various immune cells are identified to be involved in its pathogenesis.γδT cell is a kind of natural immune cell,althoughγδT cells have been reported to play an important role in some viral infectious diseases,their changes and roles in HFMD remain unclear.This study is designed to detect changes in the phenotype and function ofγδT cells in peripheral blood of HFMD patiens,and analyze the significance ofγδT cells in the pathogenesis of HFMD.Materials and Methods:1.Subjects:A total of 83 HFMD patients were enrolled,of whom 66were used for cross-sectional studies(comparision between patients and healthy controls(HCs))and 17 were used for longitudinal studies(comparision between acute and recovery stage).According to clinical manifestations or enterovirus(EV)71 RNA detection results,HFMD patients were divided into mild and severe groups or EV71-and EV71+groups.Patients with severe HFMD were further subdivided into EV71-severe and EV71+severe groups.At the same time,26 healthy children were included.2.Percentages of totalγδT cells and their subsets in peripheral blood were detected by flow cytometry,including Vδ1 T,Vδ2 T,na?veγδT(CD45RA~+CD27~+,γδTna?ve),central memoryγδT(CD45RA~-CD27~+,γδTcm),effector memoryγδT(CD45RA~-CD27~-,γδTem),effectorγδT(CD45RA~+CD27~-,γδTeff),and cytokine producedγδT cells(interferon(IFN)-γ~+γδT,tumor necrosis factor(TNF)-α~+γδT,CD107a~+γδT and Granzyme B~+γδT cells).3.Levels of plasma inflammatory cytokines(IFN-γ,TNF-α,and interleukin(IL)-6)and chemokine(monocyte chemotactic protein(MCP)-1)were examined by enzyme-linked immunosorbent assay(ELISA).4.Differences in percentages ofγδT cells and their subsets between HFMD patients and HCs,or between acute and recovery phase were statistically analyzed by software SPSS23.0.At the same time,the correlation betweenγδT cells or their subsets and clinical parameters was analyzed.P<0.05 was considered statistically significant.Results:1.Blood tests showed the counts of white blood cells(WBC)and neutrophils(N)in severe or EV71+patients were significantly higher than HCs,while the level of prealbumin(PA)was significantly lower than HCs.2.Changes ofγδT cells and their subsets in HFMD patients:2.1 The proportion of totalγδT cells in HFMD patients was not significantly different from HCs.Except for the EV71-severe group,the proportion ofγδTeff cells in peripheral blood of HFMD patinets was significantly higher than HCs,while the proportion ofγδTcm cells was significantly decreased.2.2 Compared with HCs,the proportion of Vδ1 T,γδTeff,IFN-γ~+γδT and TNF-α~+γδT cells in patients with severe HFMD increased significantly,while the percentages of Vδ2 T,γδTcm and Granzyme B~+γδT cells decreased significantly.In EV71+severe HFMD patients,γδTeff,IFN-γ~+γδT,and TNF-α~+γδT cells were also significantly increased when compared with HCs.2.3 Compared with the acute phase,the percentages of Vδ1 T andγδTeff cells in the recovery phase of patients decreased significantly and returned to relatively normal levels.3.Levels of plasma cytokines and chemokine:plasma cytokines IFN-γ,TNF-α,IL-6 and chemokine MCP-1 levels in severe HFMD patients especially in EV71-severe HFMD patients were significantly higher than HCs.4.Correlation analysis showed that in HFMD patients,IFN-γ~+γδT or TNF-α~+γδT cells were positively correlated with the percentages ofγδTem orγδTeff cells,while negatively correlated with the proportion ofγδTcm cells.At the same time,the proportion of Vδ1 T cells was positively correlated with WBC count,the proportion of IFN-γ~+γδT or TNF-α~+γδT cells was positively correlated with N count,the proportion of TNF-α~+γδT cells was positively correlated with PCT concentration,while the percentage of Vδ2 T cells was negatively correlated with WBC or N count.Conclusions:In severe HFMD patients,the percentages of peripheral Vδ1 T andγδTeff cells increased,their cytokines production enhanced,and they were positively correlated with clinical inflammatory parameters,suggesting that theseγδT cell subsets might be involved in the development of severe HFMD.