Pertussis Circulation Has Increased T-Cell Immunity during Childhood More than a Second Acellular Booster Vaccination in Dutch Children 9 Years of Age

<div><p>Here we report the first evaluation of T-cell responses upon a second acellular pertussis booster vaccination in Dutch children at 9 years of age, 5 years after a preschool booster vaccination. Blood samples of children 9 years of age were studied longitudinally until 1 year after the second aP booster and compared with those after the first aP booster in children 4 and 6 years of age from a cross-sectional study. After stimulation with pertussis-vaccine antigens, Th1, Th2 and Th17 cytokine responses were measured and effector memory cells (CCR7-CD45RA-) were characterized by 8-colour FACS analysis. The second aP booster vaccination at pre-adolescent age in wP primed individuals did increase pertussis-specific Th1 and Th2 cytokine responses. Noticeably, almost all T-cell responses had increased with age and were already high before the booster vaccination at 9 years of age. The enhancement of T-cell immunity during the 5 year following the booster at 4 years of age is probably caused by natural boosting due to the a high circulation of pertussis. However, the incidence of pertussis is high in adolescents and adults who have only received the Dutch wP vaccine during infancy and no booster at 4 years of age. Therefore, an aP booster vaccination at adolescence or later in these populations might improve long-term immunity against pertussis and reduce the transmission to the vulnerable newborns.</p> <h3>Trial Registration</h3><p>Controlled-Trials.com <a href="http://www.controlled-trials.com/ISRCTN64117538/">ISRCTN64117538</a></p> </div

Differential T- and B-Cell Responses to Pertussis in Acellular Vaccine-Primed versus Whole-Cell Vaccine-Primed Children 2 Years after Preschool Acellular Booster Vaccination

<p>This study investigated long-term cellular and humoral immunity against pertussis after booster vaccination of 4-year-old children who had been vaccinated at 2, 3, 4, and 11 months of age with either whole-cell pertussis (wP) or acellular pertussis (aP) vaccine. Immune responses were evaluated until 2 years after the preschool booster aP vaccination. In a cross-sectional study (registered trial no. ISRCTN65428640), blood samples were taken from wP- and aP-primed children prebooster and 1 month and 2 years postbooster. Pertussis vaccine antigen-specific IgG levels, antibody avidities, and IgG subclasses, as well as T-cell cytokine levels, were measured by fluorescent bead-based multiplex immunoassays. The numbers of pertussis-specific memory B cells and gamma interferon (IFN-gamma)-producing T cells were quantified by enzyme-linked immunosorbent spot assays. Even 2 years after booster vaccination, memory B cells were still present and higher levels of pertussis-specific antibodies than prebooster were found in aP-primed children and, to a lesser degree, also in wP-primed children. The antibodies consisted mainly of the IgG1 subclass but also showed an increased IgG4 portion, primarily in the aP-primed children. The antibody avidity indices for pertussis toxin and pertactin in aP-primed children were already high prebooster and remained stable at 2 years, whereas those in wP-primed children increased. All measured prebooster T-cell responses in aP-primed children were already high and remained at similar levels or even decreased during the 2 years after booster vaccination, whereas those in wP-primed children increased. Since the Dutch wP vaccine has been replaced by aP vaccines, the induction of B-cell and T-cell memory immune responses has been enhanced, but antibody levels still wane after five aP vaccinations. Based on these long-term immune responses, the Dutch pertussis vaccination schedule can be optimized, and we discuss here several options.</p>

Numbers of IFN-γ producing cells.

<p>PBMCs of children 4 years of age (red open triangles) (n = 14), 6 years of age (yellow open squares) (n = 15) and 9 years of age (blue open circles) (n = 20) pre-booster have been stimulated with PT, FHA or Prn for 5 days and subsequently numbers of IFN-γ producing cells have been determined. Children 9 years of age have been studied longitudinally at 1 month (blue closed circles) and 1 year (dark blue filled circles) post a second aP booster vaccine (n = 20) and children 4 years of age have been studied cross-sectionally at 1 month post a first aP booster vaccine (red filled triangles) (n = 11). Horizontal lines represent geometric means of IFN-γ producing cells per 100.000 stimulated PBMCs. * =  significant difference between groups.</p

Effector memory T-cell responses.

<p>Percentages of effector memory T-cells (CD45RA-,CCR7-) in children of 4 years (red filled circles) and 9 years of age (blue filled circles) found in CD3+CD4+ T-cells (A) and proliferated (CFSE-) CD3+CD4+ T-cells (B) upon stimulation with the pertussis antigens and in non-stimulated cells (NS) Horizontal lines represent geomean values. • =  significant difference between children of 4 and 9 years of age.</p

Pertussis protein-specific cytokine responses.

<p>Th1, Th2 and Th17 and IL-10 responses in supernatants of PT, FHA and Prn stimulated PBMCs of children of 4 years of age (red bars), 6 years of age (yellow bars) and 9 years of age (blue bars) are presented as GMCs with 95% confidence intervals. Additionally, cytokine responses of children 4 years of age at 1 month post a first aP booster vaccine (red hatched bars) and children 9 years of age at 1 month (blue hatched bars) and 1 year (blue cross-hatched bars) post a second aP booster vaccine are shown. * =  significant increase between groups # =  significant decrease between groups.</p

Flow-cytometry analysis of pertussis-specific CD3+CD4+ T-cells.

<p>PBMCs of children 4 and 9 years of age pre-booster were stimulated with PT and Prn for 5 days and analyzed by 8-colour FACS analysis. T-cells which have proliferated upon stimulation (CFSE-) were characterized phenotypically by CD45RA and CCR7 and the effector memory cells (CD45RA- and CCR7-) were further analyzed functionally (IFN-γ+ and TNF-α+). The results of a representative child of 4 years and 9 years of age specific for PT (A) and Prn (B) are presented.</p

Consort 2010 Flow Diagram.

<p>Study participants, during the recruitment of children 9 years of age who received <i>Boostrix-IPV</i>™ as a second aP booster vaccination.</p

Antimicrobial activity of platelet-leukocyte gel against Staphylococcus aureus

A

Different IgG-subclass distributions after whole-cell and acellular pertussis infant primary vaccinations in healthy and pertussis infected children

The distribution of IgG-subclasses provides insight in the immunological mechanisms of protection against whooping cough. We investigated the effect of Dutch whole-cell pertussis and acellular pertussis vaccines administered in infancy on the IgG-subclass distributions in healthy children aged 12 months, 4 years and 9 years as well as in children who have been infected with Bordetella pertussis. A fluorescent bead-based multiplex immunoassay was used for the measurement of IgG1, IgG2, IgG3 and IgG4 responses against pertussis toxin, filamentous heamagglutinin and pertactin. Although IgG1 was the predominant subclass for all pertussis antigens in both healthy and infected children, elevated IgG4 levels were only present in children who had received repeated number of acellular pertussis vaccinations. IgG2 and IgG3 antibodies did not contribute to the IgG response. No differences in IgG-subclasses between healthy vaccinated or infected children were found. The pertussis vaccine used for priming seems to determine the IgG-subclass composition elicited after a secondary antibody response either induced by pertussis vaccination or infection. The pronounced anti-pertussis IgG4 response might reflect the Th2-skewing of the immune response after aP vaccination. (C) 2011 Elsevier Ltd. All rights reserved