Patients with Igg subclass and/or selective antibody deficiency to polysaccharide antigens: initiation of a controlled clinical trial of intravenous immune globulin.

Selective IgG subclass deficiencies and/or selectively impaired antibody responses to bacterial capsular polysaccharide antigens have been increasingly reported. In this report, 13 children with recurrent infections and deficient antibody responses to polysaccharide antigens are described. Serum IgG2 subclass concentrations were normal in all the patients, and two children had low IgG3 levels. Mean serum antibody concentrations to the capsular polysaccharide antigens of Streptococcus pneumoniae and Haemophilus influenzae were significantly decreased after immunizations, but antibody responses to diphtheria and tetanus toxoids were normal. The identification of children with selective antibody deficiencies and recurrent infections has prompted a multicenter, double-blind, placebo-controlled study to evaluate the efficacy and safety of intravenous immune globulin therapy in these patients.