Impact of Maternal Pertussis Antibodies on the Infants' Cellular Immune Responses.

Introduction: Maternal antibody interference of the infant's humoral immune responses raises some concern to the strategy of maternal Tdap (tetanus, diphtheria, acellular pertussis [aP]) vaccination. This study assessed the impact of maternal Tdap antibodies on the infant's pertussis-specific T lymphocyte responses following infant vaccination with an aP containing vaccine, in a term and preterm born cohort.
Methods: Heparin samples (±0.5 mL) were conveniently drawn from infants of a Belgian prospective cohort study (N = 79, NCT02511327), including Tdap vaccinated (Boostrix®) and nonvaccinated women (no Tdap vaccine in the last 5 years) that delivered at term or prematurely. Sampling was performed before and 1 month after primary (8-12-16 weeks) and booster vaccination (13 or 15 months) with DTaP-IPV-HB-PRP~T vaccine (Hexyon®). Pertussis toxin (PT)-specific CD3+, CD3+ CD4+ and CD3+ CD8+ lymphoblasts and their cytokine secretions were measured using a flow cytometric assay on whole blood (FASCIA) and multiplex technology (Meso Scale Discovery), respectively.
Results: In total, 57% of all infants were considered PT-specific CD3+ CD4+ lymphoblasts responders after primary and booster vaccination, whereas 17% were CD3+ CD8+ lymphoblast responders. Interferon (IFN)-γ, interleukin (IL)-13, IL-17A, and IL-5 cytokine secretions after primary and booster vaccination were indicative of a mixed T helper (Th) 1/Th2/Th17 cell profile. Lymphoblast and cytokine levels were comparable between term and preterm infants. Nonresponders for IL-13 after booster vaccination had higher maternal PT immunoglobulin G (IgG) levels at birth when compared to responders.
Conclusions: Term and preterm born infants are capable of inducing Th1, Th2, and Th17 responses after aP vaccination, yet maternal vaccination modulate these responses. Evaluation of this effect in larger trials is needed.
Competing Interests: Potential conflicts of interest. The Universities of Antwerp and Hasselt obtain grants from several vaccine manufacturers (GSK Biologicals, Pfizer, Merck, and J&J) for specific studies aimed at modeling the spread of infectious diseases for which N. H. is the principal investigator (PI). N. H. obtains no personal renumeration. The University of Antwerp obtains grants from several small and medium-sized enterprises and vaccine manufacturers (GSK Biologicals, Pfizer, SANOFI, Merck, Takeda, Baxter, CanSino China, Themis, Osivax, J&J, and Abbott) for the conduct of vaccine trials for which P. V. D. is the investigator and for the support of the Viral Hepatitis Prevention Board. P. V. D. obtains no personal remuneration. The University of Antwerp obtains grants from foundations, EU, and Government (The Bill & Melinda Gates Foundation, PATH, Flemish Government, and European Union) for the conduct of trials and vaccine research for which P. V. D. is the PI. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.
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