Hyper-response of serum IgG1 to Staphylococcus aureus peptidoglycan in patients with hyper-IgE syndrome

The hyper-IgE (HIE) syndrome is characterized by high IgE serum levels, chronic dermatitis and recurrent infections. To determine whether an impairment of the antibody response to Staphylococcus aureus contributes to infections in this syndrome we measured total serum IgG subclass, specific IgG1 and IgG2 levels against peptidoglycan (PG), the immunodominant cell wall component of S. aureus and serum opsonic activity to PG. Of the 14 patients with HIE syndrome, nine had increased level of serum IgG1 and six had IgG2 subclass deficiency. In regard to specific response of IgG1 and IgG2 antibodies to PG, patients were divided into five groups related to ages and compared with 10 control subjects for each age cohort. Patients with HIE syndrome had significant high levels of serum-specific IgG1 to PG and significant decreased levels of serum-specific IgG2 to PG in all five groups. Additionally, serum opsonic activity in patients was significantly higher than that in normal control subjects. It is concluded that IgG2 deficiency or poor IgG2 antibody response to S. aureus is not the explanation of the abnormal susceptibility to S. aureus infections of HIE patients.