Both CD4+ and CD8+ lymphocytes participate in the IFN-y response to filamentous hemagglutinin from Bordetella pertussis in infants, children and adults

Infant CD4+ T-cell responses to bacterial infections or vaccines have been extensively studied, whereas studies on CD8 + T-cell responses focused mainly on viral and intracellular parasite infections. Here we investigated CD8 + T-cell responses upon Bordetella pertussis infection in infants, children, and adults and pertussis vaccination in infants. Filamentous hemagglutinin-specific IFN-γ secretion by circulating lymphocytes was blocked by anti-MHC-I or -MHC-II antibodies, suggesting that CD4 + and CD8 + T lymphocytes are involved in IFN-γ production. Flow cytometry analyses confirmed that both cell types synthesized antigen-specific IFN-γ, although CD4 + lymphocytes were the major source of this cytokine. IFN-γ synthesis by CD8 + cells was CD4 + T cell dependent, as evidenced by selective depletion experiments. Furthermore, IFN-γ synthesis by CD4 + cells was sometimes inhibited by CD8 + lymphocytes, suggesting the presence of CD8 + regulatory T cells. The role of this dual IFN-γ secretion by CD4 + and CD8 + T lymphocytes in pertussis remains to be investigated. © 2012 Violette Dirix et al.

Helicobacter pylori modulation of gastric and duodenal mucosal T cell cytokine secretions in children compared with adults.

BACKGROUND: In contrast to adults, ulcers are un-common in Helicobacter pylori-infected children. Since immunological determinants influence the outcome of H. pylori infection, we have investigated mucosal T cell responses in H. pylori-infected children and compared them with those of adults and negative controls. MATERIAL AND METHODS: Mucosal biopsies were obtained from 43 patients undergoing an upper GI endoscopy for dyspeptic symptoms. The concentrations of released cytokines and the density of CD3+, CD25+ and CD69+cells were evaluated by flow cytometry, and the numbers of cytokine-secreting cells were measured by ELISPOT. RESULTS: The numbers of isolated antral CD3+ lymphocytes were only significantly raised in infected adults compared with noninfected controls (p < 0.05), whereas the proportion of CD3+ cells expressing activation markers (CD25 or CD69) remained low. In the stomach, IFN-gamma concentrations increased in infected children and infected adults compared with controls (p < 0.05), but IFN-gamma concentrations were tenfold lower in children than in adults (p < 0.01). IL-2, IL-4, IL-10 and TNF-alpha concentrations were similar in infected and in uninfected children and adults. In contrast, in the duodenum, IFN-gamma, as well as IL-4 and IL-10 concentrations were only increased in infected children compared with controls (p < 0.05). The concentrations of these cytokines were similar in both groups of adults who, however, like children, displayed a higher number of duodenal IL-4-secreting cells compared to controls (p < 0.05). CONCLUSION: These results suggest that IFN-gamma secretion in the stomach of H. pylori-infected patients is lower in children than in adults. This could protect children from development of severe gastro-duodenal diseases such as ulcer disease. In addition, infected patients are characterised by a dysregulation of the mucosal cytokine secretion at distance from the infection site.

Identification of major factors influencing ELISpot-based monitoring of cellular responses to antigens from Mycobacterium tuberculosis.

A number of different interferon-gamma ELISpot protocols are in use in laboratories studying antigen-specific immune responses. It is therefore unclear how results from different assays compare, and what factors most significantly influence assay outcome. One such difference is that some laboratories use a short in vitro stimulation period of cells before they are transferred to the ELISpot plate; this is commonly done in the case of frozen cells, in order to enhance assay sensitivity. Other differences that may be significant include antibody coating of plates, the use of media with or without serum, the serum source and the number of cells added to the wells. The aim of this paper was to identify which components of the different ELISpot protocols influenced assay sensitivity and inter-laboratory variation. Four laboratories provided protocols for quantifying numbers of interferon-gamma spot forming cells in human peripheral blood mononuclear cells stimulated with Mycobacterium tuberculosis derived antigens. The differences in the protocols were compared directly. We found that several sources of variation in assay protocols can be eliminated, for example by avoiding serum supplementation and using AIM-V serum free medium. In addition, the number of cells added to ELISpot wells should also be standardised. Importantly, delays in peripheral blood mononuclear cell processing before stimulation had a marked effect on the number of detectable spot forming cells; processing delay thus should be minimised as well as standardised. Finally, a pre-stimulation culture period improved the sensitivity of the assay, however this effect may be both antigen and donor dependent. In conclusion, small differences in ELISpot protocols in routine use can affect the results obtained and care should be given to conditions selected for use in a given study. A pre-stimulation step may improve the sensitivity of the assay, particularly when cells have been previously frozen.

NF-KB Activation and Severity of Gastritis in Helicobacter pylori-Infected Children and Adults.

In contrast to adults, Helicobacter pylori gastritis in children is reported as milder and ulcer disease as uncommon, but unequivocal data are lacking.

Bordetella pertussis from functional genomics to intranasal vaccination.

Whooping cough still represents a major health problem, despite the use of effective vaccines for several decades. Being classically a typical childhood disease, whooping cough in young adults is now more common than it used to be, suggesting that protection after vaccination wanes during adolescence. As an alternative to the current vaccines, we wish to develop live attenuated vaccines to be delivered by the nasal route, such as to mimic the natural route of infection and to induce long lasting immunity. Bordetella pertussis, the etiological agent of whooping cough, produces a number of virulence factors, including toxins. Its recently determined genome sequence makes it now possible to apply functional genomics, such as transcriptomics and systematic knock-out mutagenesis. The expression of most known B. pertussis virulence genes is controlled by the two-component system BvgA/S. DNA microarray analyses have led to the identification of novel genes in the BvgA/S regulon, some of which are activated by BvgA/S and others are repressed by BvgA/S. In addition, some genes appear to be differentially modulated by nicotinic acid and MgSO4, both known to modulate the expression of BvgA/S-regulated genes. Among others, the functional genomics approach has uncovered two strongly BvgA/S-activated genes, named hotA and hotB (for 'homolog of toxin'), the products of which show high sequence similarities to pertussis toxin subunits. The identification of the full array of virulence factors, as well as an integrated understanding of the bacterial physiology should allow us to design attenuated B. pertussis strains useful for intranasal vaccination. A first generation of attenuated strains has already shown full protection in mice after a single intranasal administration. Such strains may also serve as vaccine carriers for heterologous antigens, in order to vaccinate against several different pathogens simultaneously.

Are the reference values of B cell subpopulations used in adults for classification of common variable immunodeficiencies appropriate for children?

Detailed phenotypic characterization of B cell subpopulations is of utmost importance for the diagnosis and management of humoral immunodeficiencies, as they are used for classification of common variable immunodeficiencies. Since age-specific reference values remain scarce in the literature, we analysed by flow cytometry the proportions and absolute values of total, memory, switched memory and CD21(-/low) B cells in blood samples from 168 healthy children (1 day to 18 years) with special attention to the different subpopulations of CD21(low) B cells. The percentages of total memory B cells and their subsets significantly increased up to 5-10 years. In contrast, the percentages of immature CD21(-) B cells and of immature transitional CD21(low)CD38(hi) B cells decreased progressively with age, whereas the percentage of CD21(low) CD38(low) B cells remained stable during childhood. Our data stress the importance of age-specific reference values for the correct interpretation of B cell subsets in children as a diagnostic tool in immunodeficiencies.

Loss of a major idiotype (CRIA) after repopulation of irradiated mice.

The normal immune response of A/J mice against arsonate coupled to hemocyanin is characterized by a major recurrent cross-reactive Id, the CRIA. This Id is encoded by a single gene segment combination: VHidcr11-DFL16.1e-JH2 for the H chain and Vkidcr-Jk1 for the L chain. In this report, we show that lethal irradiation of A/J mice followed by reconstitution with autologous or syngeneic lymphoid cells results in loss of major CRIA Id expression in the response to arsonate. Different protocols were performed to repopulate the irradiated mice. First, lethally irradiated A/J mice were reconstituted by the transfer of syngeneic bone marrow cells. Second, A/J mice were lethally irradiated while their hind limbs were partially shielded. Third, lethally irradiated A/J mice received a transfer of syngeneic spleen cells. The three groups of mice produce high titers of antiarsonate antibodies completely devoid of CRIA DH-JH related idiotopes expression. Moreover, a lack of affinity maturation is observed in the secondary antiarsonate response of all irradiated and reconstituted mice. A transfer of syngeneic peritoneal cells or a transfer of primed T cells in irradiated and reconstituted A/J mice do not restore in a significant manner either the recurrent CRIA expression or the affinity maturation of the antiarsonate response. Our data suggest that the choice of this Id is not solely dictated by the Igh locus.

Dry deposition and heavy acid loading in the vicinity of Masaya Volcano, a major sulfur and chlorine source in Nicaragua

info:eu-repo/semantics/published

Analytical laboratory comparison of major and minor constituents in an active crater lake

info:eu-repo/semantics/published