Immunoglobulin G (IgG) subclasses and human disease

The isotypes of IgG, IgG1, IgG2, IgG3, and IgG4 were determined in immunoglobulin preparations and the effect on serum levels of treated patients. Serum IgG subclass deficiencies were recorded in different patient groups: (1) IgG2-IgG4 deficiency was associated with IgA deficiency. (2) IgG2-IgG4 deficiency was found in patients with ataxia telangiectasia. (3) Low IgG2 levels were recorded in patients with SLE; one of these patients with...