Identification of B cell defects using age-defined reference ranges for in vivo and in vitro B cell differentiation.

Daan J aan de Kerk, Machiel H Jansen, Ineke J M ten Berge, Ester M M van Leeuwen, Taco W Kuijpers

Department of Pediatric Hematology, Immunology, and Infectious Diseases, Emma Children's Hospital, Academic Medical Center, 1105 AZ Amsterdam, The Netherlands. d.j.aandekerk@amc.nl

Journal of immunology (Baltimore, Md. : 1950) 2013 May 15

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Primary immunodeficiencies consist to a large extent of B cell defects, as indicated by inadequate Ab levels or response upon immunization. Many B cell defects have not yet been well characterized. Our objective was to create reliable in vivo and in vitro assays to routinely analyze human B cell differentiation, proliferation, and Ig production and to define reference ranges for different age categories. The in vitro assays were applied to classify the developmental and/or functional B cell defects in patients previously diagnosed with common variable immunodeficiency. Apart from standard immunophenotyping of circulating human B cell subsets, an in vitro CFSE dilution assay was used for the assessment of proliferative capacity comparing T cell-dependent and T cell-independent B cell activation. Plasmablast/plasma cell differentiation was assessed by staining for CD20, CD38, and CD138, and measurement of in vitro Ig secretion. At young age, B cells proliferate upon in vitro activation, but neither differentiate nor produce IgG. These latter functions reached adult levels at 5 and 10 y of age for T cell-dependent versus T cell-independent stimulations, respectively. The capacity of B cells to differentiate into plasmablasts and to produce IgG appeared to be contained within the switched memory B cell pool. Using these assays, we could categorize common variable immunodeficiency patients into subgroups and identified a class-switch recombination defect caused by an UNG mutation in one of the patients. We defined age-related reference ranges for human B cell differentiation. Our findings indicate that in vivo B cell functionality can be tested in vitro and helps to diagnose suspected B cell defects.

Citation

Daan J aan de Kerk, Machiel H Jansen, Ineke J M ten Berge, Ester M M van Leeuwen, Taco W Kuijpers. Identification of B cell defects using age-defined reference ranges for in vivo and in vitro B cell differentiation. Journal of immunology (Baltimore, Md. : 1950). 2013 May 15;190(10):5012-9