Autoimmune neutropenia of infancy (ANI) is a common, usually benign disease; certain patients however have repeated and/or serious infections suggesting that other immunologic abnormalities could be present. We investigated 5 recurrently ill pts. with absolute neutrophil counts (ANC) < 200, and high level anti-neutrophil antibodies. Prior to treatment all patients had <50% of the nl IgG2 level and <80% of the nl IgG3 levels despite nl total IgG levels. 3 of 5 had decreased natural killer activity to K562 although 4 of 5 had normal lymphocyte responses to PHA. All 5 patients responded to Intravenous Gammaglobulin (IVGG) at a dose of 2 to 5 gm/kg (avg. 3 gm/kg) with ANC >1000 within 5 days and clinical improvement. Neutrophil function was nl in 2/2 pts tested after the ANC increased. After an average of 10 mos. 4 pts. were in remission and the fifth had an ANC of 600. Natural killer activity was nl in 4/4 patients in remission but IgG2 levels remained low in 2/2 patients. ANI may be associated with IgG2 and/or IgG3 subclass deficiencies and decreased natural killer activity which could explain why these pts. were particularly ill. The NK abormalities resolved when the neutrophil antibodies disappeared but IgG2 deficiency persisted. IVGG appeared to have a longer lasting clinical effect than the elevation of the ANC (2 weeks).
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Bussel, J., Hilgartner, M., Lalezari, P. et al. 894 AUTOIMMUNE NEUTROPENIA: ASSOCIATION WITH LOW IgG2 DECREASED NATURAL KILLER ACTIVITY. Pediatr Res 19, 259 (1985). https://doi.org/10.1203/00006450-198504000-00924