Characterization of serum anti-gliadin IgA in childhood coeliac diseases versus other gastrointestinal diseases and controls.

info:eu-repo/semantics/nonPublished

Early cellular immune response to a new candidate mycobacterial vaccine antigen in childhood tuberculosis

The search for novel vaccines against tuberculosis (TB) would benefit from in-depths knowledge of the human immune responses to Mycobacterium tuberculosis (Mtb) infection. Here, we characterised in a low TB incidence country, the immune responses to a new candidate vaccine antigen against TB, the heparin-binding haemagglutinin (HBHA), in young children in contact with an active TB case (aTB). Children with no history of BCG vaccination were compared to those vaccinated at birth to compare the initial immune responses to HBHA with secondary immune responses. Fifty-eight children with aTB and 76 with latent TB infection (LTBI) were included and they were compared to 90 non-infected children. Whereas Mtb-infected children globally secreted more interferon-gamma (IFN-γ) in response to HBHA compared to the non-infected children, these IFN-γ concentrations were higher in previously BCG-vaccinated compared to non-vaccinated children. The IFN-γ concentrations were similar in LTBI and aTB children, but appeared to differ qualitatively. Whereas the IFN-γ secretion induced by native methylated and recombinant non-methylated HBHA were well correlated for aTB, this was not the case for LTBI children. Thus, Mtb-infected young children develop IFN-γ responses to HBHA that are enhanced by prior BCG vaccination, indicating BCG-induced priming, thereby supporting a prime-boost strategy for HBHA-based vaccines. The qualitative differences between aTB and LTBI in their HBHA-induced IFN-γ responses may perhaps be exploited for diagnostic purposes.

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.