Immunological and haematological changes during high-dose immunoglobulin therapy in an infant with autoimmune neutropenia.

High-dose immunoglobulin (HD-Ig) therapy was given to an infant with autoimmune neutropenia (AIN), and antineutrophil autoantibodies (ANAA). The patient's absolute neutrophil count in peripheral blood increased from 300/mm3 to 3000-4000/mm3 7 days after treatment. Although the neutrophil count gradually decreased thereafter, transient increases were observed after each single booster infusion repeated at 3-week intervals. By continuing this treatment, clinical symptoms were markedly alleviated, and the patient's susceptibility to infection was reduced. The increase in neutrophils showed a positive correlation with the increase in serum IgG, and with the increase in the ratio of the T helper/T suppressor cells. The neutrophil-bound IgG level and serum lysozyme level were decreased after HD-Ig therapy.