Quantification of IgG subclasses in sera of normal adults and healthy children between 4 and 12 years of age.

The concentration of the four subclasses of IgG was determined in sera of normal adults and healthy children between 4 and 12 years of age, using the radial immunodiffusion technique. A relation between the concentration of IgG subclasses and Gm type was studied in adults. No influence of Gm type on IgG1 concentration could be shown, except that the group of Gm(fb) individuals had a higher level than the others. The mean concentration of IgG2 was higher in sera positive for Gm(n) than in those lacking this genetic marker. High IgG3 concentrations corresponded to the presence of Gm(b). No clearcut evidence was obtained for a relation between IgG4 concentration and Gm factors, although in general Gm(n) positive individuals had higher and Gm (zag) positive individuals lower concentrations of this subclass in their serum. Quantification of IgG subclasses in sera from healthy children of different ages revealed that the amount of IgG2 rises slowly with age, having not yet reached the adult level at the age of 12 years. This also holds for IgG4, although in a lesser degree. No significant differences from the adult level were found for the concentrations of IgG1 and IgG3.