Analysis of IgG subclasses in chronic active Epstein-Barr virus infection

Background: Although elevated serum levels of immunoglobulins are frequentl y observed in patients with chronic active Epstein-Barr virus (EBV) infecti on, there have been no reports concerning levels of IgG subclasses, Methods: Serum levels of IgG subclasses were measured by the enzyme-linked immunosorbent assay (ELISA) in 30 children with severe chronic active EBV i nfection. Results: Serum levels of IgG1 were elevated in most patients, except for on e who showed an abnormally low level of IgG1 and progressive hypogammaglobu linemia. Serum levels of IgG2, IgG3 and IgG4 in the patients were comparabl e to those in control children, while abnormally low levels of IgG2, IgG3 a nd IgG4 were observed in six, three and four cases, respectively. Conclusion. Although not always susceptible to bacterial infections, low le vels of IgG2 were frequently observed in patients with chronic active EBV i nfection and elevated IgG1 is responsible for the increase of serum IgG in these patients.