title: Establishment of age-dependent reference values for IgA subclasses.
abstract: BACKGROUND
  Recently, subclass-specific antisera have been introduced for application in a nephelometric assay. The aim of this study was to establish age-dependent reference values for serum concentrations of the two IgA subclasses in children and adults.
  
  
  METHODS
  Serum levels of IgA1 and IgA2 were measured by automated immunonephelometry in samples from 235 clinically healthy children between 6 months and 18 years of age and 36 healthy adults.
  
  
  RESULTS
  Both IgA1 and IgA2 were detectable in all samples, and both IgA1 and IgA2 increased with increasing age. In adults, the mean value for IgA1 is 1.46 g/l for IgA2 0.21 g/l and for total IgA 1.94 g/l. Individual IgA2 values correlate significantly (p < 0.0001) with IgA1 values (r(2) = 0.5433). In addition, there was a highly significant (p < 0.0001) correlation (r(2) = 0.9530) between the measured total IgA and the sum of the two IgA subclasses indicating that immunonephelometry using highly specific polyclonal antisera might be superior to other methods.
  
  
  CONCLUSIONS
  These results and the availability of age-dependent reference values make it worthwhile to reassess the role of IgA subclasses in immunodeficiency and autoimmune diseases where conventional methods have led to conflicting results.
authors.affiliation: Klinik für Kinder-und Jugendmedizin der Ruhr Universität Bochum, St Josef-Hospital, Alexandrinenstr 5, D-44791 Bochum, Germany. uwe.schauer@ruhr-uni-bochum.de
authors.forename: Uwe
authors.initials: U
authors.lastname: Schauer
authors.forename: Frank
authors.initials: F
authors.lastname: Stemberg
authors.forename: Christian H L
authors.initials: CH
authors.lastname: Rieger
authors.forename: Michael
authors.initials: M
authors.lastname: Borte
authors.forename: Simone
authors.initials: S
authors.lastname: Schubert
authors.forename: Frank
authors.initials: F
authors.lastname: Riedel
authors.forename: Udo
authors.initials: U
authors.lastname: Herz
authors.forename: Harald
authors.initials: H
authors.lastname: Renz
authors.forename: Manfred
authors.initials: M
authors.lastname: Wick
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Herzog
mesh_terms: D000328:Adult; D000367:Age Factors; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000145:classification*; D008297:Male; D008875:Middle Aged; D012016:Reference Values
chemical_list: D007070:Immunoglobulin A