Preferential induction of a KLH-specific T helper 1–type cytokine profile. (A) IFN-γ, IL-2, IL-4, IL-5, and IL-10 cytokine secretion of PBLs after in vitro restimulation with KLH. Prevaccination and postvaccination PBLs were stimulated in vitro with KLH for 4 days, and cytokine levels were measured in cell-free supernatants by ELISA. Values represent cytokine concentrations in pg/mL produced by 10⁶ cells in 1 mL complete medium. Negative control using FCS containing complete medium showed cytokine production above the detection limit of the ELISA. ▪ indicates patient 1; •, patient 2; ▴, patient 3; □, patient 4; and ○, patient 5. (B) IFN-γ/IL-4 ratio, as indicator of the preferential cytokine pattern, by PBLs after antigen-specific restimulation with KLH (left panel) or polyclonal stimulation with PHA (right panel). ▪ indicates patient 1; •, patient 2; ▴, patient 3; □, patient 4; and ○, patient 5. (C) Intracellular IFN-γ and IL-4 staining of long-term KLH-specific T-cell lines generated in patients 1, 3, and 5.