Co-stimulation of T cells via CD28 inhibits human IgE production; reversal by pertussis toxin

Immunity to Bordetella pertussis

Bordetella pertussis exploits extracellular and intracellular niches in the respiratory tract and a variety of immune evasion strategies to prolong its survival in the host. This article reviews evidence of complementary roles for cellular and humoral immunity in protection. It discusses the effector mechanisms of bacterial elimination, the strategies employed by the bacteria to subvert protective immune responses and the immunological basis for systemic and neurological responses to infection and vaccination.

Booster immunization of children with an acellular pertussis vaccine enhances Th2 cytokine production and serum IgE responses against pertussis toxin but not against common allergens

Acellular pertussis vaccines (Pa) protect against severe pertussis in children. However, serum antibody responses decline quickly after immunization. Studies in animal models suggest that cell-mediated immunity also contributes to protection against Bordetella pertussis, and it has already been demonstrated that Pa induce T cells that secrete type-1 and type-2 cytokines in children. In this study we examined the persistence of the T cell response and the effect of booster immunization in 4-6-year-old children. Cell-mediated immunity to B. pertussis antigens was detected in a high proportion of children more than 42 months after their last immunization. Peripheral blood mononuclear cells (PBMC) from the majority of children secreted interferon-gamma (IFN-gamma) and a smaller proportion IL-5, in response to specific antigen stimulation in vitro. However, following booster immunization, significantly higher concentrations of IL-5, but not IFN-gamma, were produced by PBMC in response to B. pertussis antigens. Furthermore, plasma IL-4 and IL-5 concentrations were increased, whereas IFN-gamma concentrations were reduced following booster immunization. It has been suggested that childhood immunization with Th2-inducing vaccines may predispose some children to atopic disease. Although we found that pertussis toxin (PT)-specific IgE was significantly increased after booster immunization in both atopic and non-atopic children, the levels of IgE to common allergens and the prevalence of positive skin prick test were unaffected by the booster vaccination. Thus, despite the enhancement of type-2 responses to B. pertussis antigens, booster vaccination with Pa does not appear to be a risk factor for allergy.

Association of SWAP-70 with the B cell antigen receptor complex

SWAP-70 is a component of an enzyme complex that recombines Ig switch regions in vitro. We report here the cloning of the human cDNA and its B lymphocyte-specific expression. Although its sequence contains three nuclear localization signals, in small resting B cells, SWAP-70 is mainly found in the cytoplasm. On stimulation, SWAP-70 translocates to the nucleus. In activated, class-switching B cell cultures, it is associated with membrane IgG, but not IgM. The membrane Ig association requires a functional pleckstrin homology domain and is controlled by the C terminus. We suggest that SWAP-70 is involved not only in nuclear events but also in signaling in B cell activation.

Effect of acellular pertussis vaccine on the development of allergic sensitization to environmental allergens in adults

BACKGROUND

Exposure of children to pertussis antigens caused by infection or vaccination with whole-cell pertussis vaccine may increase the serum IgE level and predispose to sensitization to the prevalent environmental allergens. Acellular pertussis vaccine (APV) that may be given to adults may have a similar effect.

OBJECTIVE

The purpose of this study was to determine whether APV will cause an increase in environmental sensitization measured by an increase of serum-specific IgE to the allergens to which adults are exposed during the vaccination period.

METHODS

One hundred adult hospital employees were randomized to receive either a 2-component APV composed of pertussis toxin and filamentous hemagglutinin or a meningococcal vaccine as a control. Serum-specific IgE level to 2 indoor allergens, cat and dust mite, and 2 outdoor allergens prevalent during the immunization season, Alternaria species and ragweed, was measured by an RIA on sera collected before and 1 month after vaccination.

RESULTS

The group that received the APV had no significant change in their serum-specific IgE levels to cat, dust, Alternaria species, or ragweed 1 month after vaccination.

CONCLUSION

A 2-component APV did not predispose to an increase of allergen-specific IgE in an adult population.

Genetically derived toxoids for use as vaccines and adjuvants

Until very recently, development of vaccines has been based on an empirical approach. For example, bacterial toxins have been detoxified using empirical chemical treatment. Progress in biotechnology and molecular biology has allowed the fine knowledge of the structure-function relationship of several bacterial toxins. Thanks to this, the genetic attenuation of bacterial toxins has been made possible. Following this approach, a genetically detoxified pertussis toxin has been produced. This molecule is now the component of an acellular pertussis vaccine, which has been shown to be highly immunogenic and efficacious in infants. The same strategy of molecular detoxification of bacterial toxins has been applied to cholera toxin and to the Escherichia coli heat-labile enterotoxin. Toxin mutants devoid of any toxic activity have been produced and shown in animals to be highly immunogenic and to exhibit strong adjuvanticity when administered at mucosal sites in conjunction with several antigens. These successful results show that rational design of stronger and safer vaccines is feasible.

Molecular basis of vaccination

Vaccines represent the most cost-effective means to prevent infectious diseases. Most of the vaccines which are currently available were developed long before the era of molecular biology and biotechnology. They were obtained following empirical approaches leading to the inactivation or to the attenuation of microorganisms, without any knowledge neither of the mechanisms of pathogenesis of the disease they were expected to protect from, nor of the immune responses elicited by the infectious agents or by the vaccine itself. The past two decades have seen an impressive progress in the field of immunology and molecular biology, which have allowed a better understanding of the interactions occurring between microbes and their hosts. This basic knowledge has represented an impetus towards the generation of better vaccines and the development of new vaccines. In this monograph we briefly summarize some of the most important biotechnological approaches that are currently followed in the development of new vaccines, and provide details on an approach to vaccine development: the genetic detoxification of bacterial toxins. Such an approach has been particularly successful in the rational design of a new vaccine against pertussis, which has been shown to be extremely efficacious and safe. It has been applied to the construction of powerful mucosal adjuvants, for administration of vaccines at mucosal surfaces.

Interleukin-12 suppresses immunoglobulin E production but enhances immunoglobulin G4 production by human peripheral blood mononuclear cells

The effect of interleukin-12 (IL-12) on human immunoglobulin G4 (IgG4) and IgE production was examined with cells derived from filarial patients and European controls. IL-12 inhibited IgE release but enhanced IgG4 production in cultures of peripheral blood mononuclear cells stimulated with anti-CD2 plus IL-2. When purified T- and B-cell cocultures were examined, IL-12 again markedly enhanced IgG4, whereas IgE production was no longer inhibited.