CD4 and hemorrhagic fever with renal syndrome: Second, the biological cytolytic function of CD4+T cells was determined by the cytotoxic assay, in which the CD4+T cells of HFRS patients could lyse HTNV-Gn/Gc peptides-pulsed autologous or MHC class II partial matched B lymphoblastic cell lines (B-LCLs) with the average percentage of 22.63 (range, 10.92–45.93) at effector-to-target cell ratio of 200:1.