Giant cell arteritis

Giant cell arteritis (GCA) or Horton's disease is a systemic granulomatous vasculitis of medium–and large–sized arteries. This is an antigen–driven disease with local T–cell and macrophage activation in the vessel wall and with an important role of proinflammatory cytokines. GCA is also called “temporal arteritis” because it involves often the superficial temporal arteries. The condition affects especially the extracranial branches of the carotid artery, but recently, GCA has been recognised to also affect limb arteries and the aorta with high prevalence.

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.