Establishment of age-dependent reference values for IgA subclasses.
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.
Schauer
Uwe
U
Klinik für Kinder-und Jugendmedizin der Ruhr Universität Bochum, St Josef-Hospital, Alexandrinenstr 5, D-44791 Bochum, Germany. uwe.schauer@ruhr-uni-bochum.de
Stemberg
Frank
F
Rieger
Christian H L
CH
Borte
Michael
M
Schubert
Simone
S
Riedel
Frank
F
Herz
Udo
U
Renz
Harald
H
Wick
Manfred
M
Herzog
Wilhelm
W
D000328:Adult; D000367:Age Factors; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000145:classification*; D008297:Male; D008875:Middle Aged; D012016:Reference Values
D007070:Immunoglobulin A