Two Th epitopes augment HER2_63-71-specific CD8+ T cell immune responses equivalently. Pre-immunization of the mice twice with either of the two Th epitopes was followed by two immunizations with the corresponding Th epitope and HER2_63-71. An essentially equivalent increase in the number of HER2_63-71-specific CD8+ T cells was observed with the two Th epitopes. The data shown are the mean ± SEM of three independent experiments.