Selective IgG2,4 subclass and IgE deficiencies in an adult patient with recurrent pneumonia

A 28-year-old woman with recurrent pneumonia was found to have selective IgG2, 4 subclass and IgE deficiencies. She had a history of repeated episodes of otitis media and sinusitis in childhood. Her total immunoglobulin level was slightly below the normal range, and selective deficiencies of IgG2, 4 and IgE were found. Although lymphocyte responses to several mitogens were within the normal ranges, peripheral blood mononuclear cells produced only IgM when stimulated by Staphylococcus aureus Cowan 1 and interleukin-2. Gene deletion of the IgG2, 4 subclass was not found, but polymorphism of the IgG gene was detected by DNA analysis of the patient's lymphocytes.