Sir.—A 21-month-old female infant with acquired immunodeficiency syndrome (AIDS) was found to have an isolated IgG4 subclass deficiency. She died, and it was found at postmortem examination that she had a disseminated undifferentiated B-cell lymphoma. Specific immunoglobulin subclass deficiencies have previously been reported in patients with persistent or recurrent respiratory tract infections and recently in infants with AIDS. However, to our knowledge, an isolated deficiency of IgG4 has not previously been reported to be associated either with AIDS or with the development of B-cell lymphoma.
Patient Report.—The patient was a 21-month-old Hispanic female infant admitted to Harbor-UCLA Medical Center, Torrance, Calif, because of unremitting diarrhea of two weeks' duration. She was the product of a term gestation with normal birth weight. There was chronic anemia, for which blood transfusions were given at 1 and 2 months of age. There were subsequently multiple episodes of diarrhea that often required