title: The B-cell compartment in antibody-deficient infants and young children - developing common variable immunodeficiency or transient immune maturation?
abstract: BACKGROUND
  Hypogammaglobulinemia in early childhood is a common feature characterized by distinct intrinsic and extrinsic factors leading to disturbed peripheral blood lymphocyte homeostasis. Detailed flow cytometric immunophenotyping of the peripheral blood B cell compartment is an informative tool for delineating disturbed generation of B cell subpopulations crucial for the diagnosis of hypogammaglobulinemia in young children.
  
  
  METHODS
  We analyzed by flow cytometry the proportions and absolute values of total, naïve, memory - non-switched and switched, transitional and immature B lymph cells as well as plasmablasts in the peripheral blood of 50 hypogammaglobulinemic children aged from 3 to 50 months.
  
  
  RESULTS
  Beyond physiological, age-related changes within the B cell pool, a proportion of children manifested defective differentiation into switched memory and accumulation of CD21lo immature B cells.
  
  
  CONCLUSIONS
  Dynamic shifts within B cell subpopulations of the immature immune system being most prominent during the first two years of life contribute to the age-related developmental abnormalities of the B cell compartment. Therefore, a reliable diagnosis of common variable immunodeficiency (CVID) in young hypogammaglobulinemic children cannot yet be established despite their clinical and immunological phenotypes sharing common features with this primary immunodeficiency.
authors.affiliation: Department of Pediatric Pneumonology, Allergology and Clinical Immunology, Karol Marcinkowski University of Medical Sciences, Szpitalna Street 27/33, 60-572, Poznan, Poland. ola@malwa.com.pl.
authors.forename: Aleksandra
authors.identifier: http://orcid.org/0000-0001-7244-1882
authors.initials: A
authors.lastname: Szczawinska-Poplonyk
authors.affiliation: Department of Pediatric Pneumonology, Allergology and Clinical Immunology, Karol Marcinkowski University of Medical Sciences, Szpitalna Street 27/33, 60-572, Poznan, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Tapolska-Jozwiak
authors.affiliation: Department of Immunology, Karol Marcinkowski University of Medical Sciences, Rokietnicka 5D, 60-806, Poznan, Poland.
authors.forename: Husam
authors.initials: H
authors.lastname: Samara
mesh_terms: D000361:Agammaglobulinemia / Q000276:immunology* / Q000503:physiopathology; D000367:Age Factors; D000906:Antibodies / Q000032:analysis / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D002675:Child, Preschool; D015331:Cohort Studies; D017074:Common Variable Immunodeficiency / Q000175:diagnosis* / Q000276:immunology*; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D005500:Follow-Up Studies; D006801:Humans; D016130:Immunophenotyping / Q000379:methods; D007223:Infant; D008297:Male; D012189:Retrospective Studies; D018570:Risk Assessment; D012737:Sex Factors
chemical_list: D000906:Antibodies
keywords: B lymph cells; Children; Hypogammaglobulinemia; Immunophenotype