IL2 and pertussis: In general, the B. pertussis-specific T-cell cytokine concentrations increased significantly with age already before the booster vaccinations and independently of the stimulatory antigen; all pertussis-specific Th1 and Th2 and IL-10 responses were higher at 9 years compared with children of 4 of age, except for PT-specific IL-2 and Prn-specific IL-10.