Reference ranges for IgG subclasses in preschool children.

A normal range for IgG1, IgG2, and IgG3 subclasses has been established for children aged 6 months to 5 years using commercially available monoclonal antisera. Of particular interest were the very low concentrations of IgG2 in some healthy children, a finding which casts doubt on the importance of IgG2 deficiency reported in some patients with otherwise unexplained infections. It was not possible to construct a normal range for IgG4 values probably because these segregate into two populations in normal subjects.