Immunoglobulin G (IgG) subclasses and human disease

The isotypes of IgG, IgG 1, IgG 2, IgG 3, and IgG 4 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) IgG 2–IgG 4 deficiency was associated with IgA deficiency. (2) IgG 2–IgG 4 deficiency was found in patients with ataxia telangiectasia. (3) Low IgG 2 levels were recorded in patients with SLE; one of these patients with recurrent pericarditis was treated with immunoglobulin with good results. (4) Low IgG 2 and/or low IgG 3 levels were found in patients with juvenile diabetes mellitus. (5) Mothers giving birth to severely group B streptococci infected infants showed low levels of IgG subclasses indicating that the newborns were IgG subclass deficient at birth. (6) In a prospective study of children with recurrent otitis media aged 12 and 32 months the IgG 2 levels were significantly reduced in the group with considerably high otitis proneness. In patients with IgG 2–IgG 4 deficiency, absence of antibodies to polysaccharide antigen teichoic acid and the protein antigen α-toxin of staphylococci was demonstrated. Imbalanced IgG subclass pattern with increased IgG 4 was recorded in patients with different diseases such as atopic diseases and also in combination with increased IgE, Henoch-Schönlein vasculitis, idiopathic pulmonary hemosiderosis, chronic mucocutaneous candidiasis, and in patients with Trichuris trichurea infection.