Increased effector γδ T cells with enhanced cytokine production are associated with inflammatory abnormalities in severe hand, foot, and mouth disease

•Enhanced effector functions of γδ T cells in severe HFMD patients compared to HCs•Effector γδ T cells were positively correlated to IFN-γ+γδ T or TNF-α+γδ T cells.•Plasma levels of IFN-γ, TNF-α, IL-6 or MCP-1 increased in severe HFMD patients.•γδ T cells subsets were associated with inflammation indicators (WBC, N, and PCT).•Decreased Vδ1 T and effector γδ T cells in the recovery phase of HFMD