GZMB and hemorrhagic fever with renal syndrome: Notably, we observed inverse correlations between the frequency of IFN-γ or granzyme B-secreting CD4+T cells and the level of serum creatinine (P = 0.023, r = −0.505 for IFN-γ+CD4+T cells and P = 0.034, r = −0.477 for granzyme B+CD4+T cells) (Fig 5C), while positive correlations between the frequency of IFN-γ or granzyme B-secreting CD4+T cells and the number of platelets in HFRS patients (P = 0.036, r = 0.472 for IFN-γ+CD4+T cells and P<0.001, r = 0.742 for granzyme B+CD4+T cells) (Fig 5D).