Quantitative and qualitative investigations of serum IgG subclasses in immunodeficiency diseases.

Determinations of IgG subclasses were made by electroimmunoassay and crossed immunoelectrophoresis, and Gm markers were typed in sera from seventeen patients with well-defined immunodeficiency diseases. Certain IgG subclass and Gm patterns were recognized in various diseases: IgG2 deficiency and homozygosity of Gm (4,5) in the cartilage-hair-hypoplasia syndrome, in the ataxia telangiectasia syndrome and in selective IgG subclass deficiency; and IgG3 deficiency and homozygosity of Gm(1,-5) in the Wiskott-Aldrich syndrome. The findings suggest a common structural or regulator gene defect in some immunodeficiency diseases. In IgA deficiencies, the levels of IgG1 were raised. In patients with IgG subclass deficiencies there was sometimes a compensatory increase of the remaining IgG subclasses, with a preponderance of IgG1 and IgG3. The increased Ig1 showed restricted heterogeneity with only an increase of the electrophoretically cathodal part. This part contained both kappa and lambda chaings. IgG subclass deficiency indicates treatment with gammaglobulin even if the serum levels of IgG are normal or increased.