Kinetics of HBsAg-specific IL-2–and IFN-γ–producing CD4+ T lymphocytes in the study population. PBMC were stimulated with αCD28 and αCD49d and HBsAg for 6 h in the presence of Brefeldin A for the last 5 h of incubation. Thereafter, the percentage of IL-2+ (A, C, E, and G) or IFN-γ+ (B, D, F, and H) cells was determined for the different T cell subsets. T cell subsets were defined by expression of cell surface markers CD4, CD45RO, and CCR7. The following subsets were defined Tnaive (CD4+CD45RO−CCR7+), Tcm cells (CD4+CD45RO+CCR7+), and Tem cells (CD4+CD45RO+CCR7−). ▪, Signals observed for healthy volunteers; □, signals observed for patients with ESRD. On the x axis, the various time intervals are depicted, and on the y axis, mean ± SEM percentages of HBsAg-specific cytokine-producing CD4+ (A and B), Tnaive (C and D), Tcm (E and F), and Tem (G and H) cells are displayed, respectively. *Significantly (P < 0.05) different from healthy volunteers.