A form of hypogammaglobulinemia that usually appears between 15 and 35 years of age. Patients have total immunoglobulin levels of less than 300 mg/dl, IgG levels of less than 250 mg/dl, a propensity to infection, lymphadenopathy, and splenomegaly. The cause is unknown. Patients should not be vaccinated with live attenuated (weakened) vaccines because of the risk of infection from the injection. Treatment includes intravenous immune globulin (200-400 mg/kg) each month and administration of specific antibiotics when needed for specific infections. Although patients often live normal life spans, chronic lung disease is a common complication and may cause an earlier than expected death.