IgG subtype abnormalities with normal total IgG in a clinical allergy practice.

Thirty-one of 75 patients with recurrent upper respiratory infections were found to have immunoglobulin G subclass deficiencies with normal levels of total immunoglobulin G in a clinical allergy and asthma practice. Sixteen were IgG3 deficient, thirteen IgG2 deficient, and two were IgG1 deficient. Only one patient had an IgA deficiency. Two patients have normal IgG with decreased PRP titers. Serum antibody titers to the capsular polysaccharide of Haemophilus influenzae type B (HibCP) were found to be low in seven patients. Other investigators have established relationships between these deficiencies and recurrent infections. When investigating patients with recurrent infections, it seems prudent to look beyond simple quantitative immunoglobulins.