Whooping cough remains a problem despite vaccination and worldwide resurging of pertussis is evident. Since cellular immunity plays a role in long-term protection against pertussis, we studied pertussis-specific T-cell responses. We compared T-cell memory responses in children, who have been primed during infancy with either a whole-cell-pertussis (wP) or an acellular-pertussis (aP) vaccine around the preschool aP booster dose at 4 years of age. PBMCs were isolated and stimulated with pertussis-vaccine antigens for 5 days. T-cells were characterized by flow-based analysis of CFSE dilution, and CD4, CD3, CD45RA, CCR7, IFN-γ and TNF-α expression. Before the aP preschool booster vaccination, both the proliferated PT-specific CD4+ and CD8+ T-cell fraction (CFSEdim) was higher in aP- compared to wP-primed children. Post-booster, more pertussis-specific CD4+ effector memory cells (CD45RA–CCR7–) were induced in aP-primed children compared to those primed with wP. The booster vaccination did not appear to significantly affect the T-cell memory subsets and functionality neither in aP-primed nor in wP-primed children. Although the percentages of Th1 cytokine producing cells were alike in aP- and wP-primed children pre-booster, aP-primed children produced more Th1 cytokines due to higher numbers of proliferated pertussis-specific effector memory cells. At present infant vaccinations with four aP vaccines in the first year of life result inpertussis-specific CD4+ and CD8+ effector memory T-cell responses that persist in children until 4 years of age and are higher than in wP-primed children. The booster at 4 years of age is therefore questionable; this may be postponed to 6 years of age.
Journal:Clin Vaccine Immunol. 2015