Vaccination of pregnant women is recommended for some infectious diseases in order to protect both women and offspring through high titres of maternal IgG antibodies. Less is known on the triggering of cellular immune responses by vaccines administered during pregnancy. In an ongoing study on maternal pertussis vaccination (2012-2014) 18 pregnant women were vaccinated with a tetanus-diphtheria-acellular pertussis (Tdap) containing vaccine (Boostrix®) during the third pregnancy trimester. Sixteen age-matched nonpregnant women received the same vaccine in the same time period. A blood sample was taken at the moment of, but before vaccination and one month and one year after vaccination. Anti-Pertussis Toxin (PT), filamentous hemagglutinin (FHA), pertactin (Prn), tetanus toxin (TT) and diphtheria toxin (DT) antibodies were measured by ELISA. Cellular immune responses were analyzed using a diluted whole blood assay, measuring proliferation, and cytokine release in response to vaccine antigens PT, FHA, TT, and to pokeweed mitogen (PWM) as polyclonal stimulus. Antibody levels to all five vaccine components increased significantly and to the same extent after vaccination in pregnant and nonpregnant women. One year after vaccination, antibody titres had decreased particularly to PT, but they were still significantly higher to all antigens than before vaccination. In contrast, proliferative and IFN-γ responses were increased to TT, PT, and FHA in nonpregnant women one month after vaccination, whereas in pregnant women only TT specific T cell responses were increased and to a lesser extent than in the control group. One year after vaccination, cellular responses equaled the baseline levels detected prior to vaccination in both groups. In conclusion, a Tdap vaccination can increase vaccine specific IgG antibodies to the same extent in pregnant and in nonpregnant women, whereas the stimulation of vaccine specific Th1 type cellular immune responses with this acellular vaccine is transient and impaired during pregnancy.
