Differential diagnosis and clinical course of autoimmune neutropenia in infancy: comparison with congenital neutropenia

Abstract

Aim: Autoimmune neutropenia in infancy (AIN) is caused by granulocyte‐specific autoantibodies. Clinical presentation and diagnosis have not been well studied, resulting in cumbersome diagnostic investigations and unnecessary treatment such as granulocyte colony‐stimulating factor (G‐CSF) therapy. Methods: Clinical, laboratory and immunological data of 18 infants with AIN were evaluated. Granulocyte‐specific autoantibodies were detected by the direct granulocyte immuno‐fluorescence test (D‐GIFT), indirect granulocyte immunofluorescence test (I‐GIFT) and immuno‐blotting. Results: The average age of onset and resolution of neutropenia in AIN was 7.4 ± 3.4 mo (mean ± SD) and 20.4 ± 4.9 mo, respectively. Sixteen of the 18 patients presented with mild infectious symptoms; the other 2 patients were detected by chance and presented with no infectious symptoms. D‐GIFT was positive in all patients, and I‐GIFT was positive in 17 of these 18 patients. Most patients showed preferential binding to neutrophils from NA(1 + 2−)‐phenotyped donors by I‐GIFT and immunoblotting. An antibiotic (sulfamethoxazole‐trimethoprim) was given to 15 patients for prophylaxis. G‐CSF was given to only one infectious patient. Conclusion: A combination of diagnostic tests for the detection of granulocyte‐specific autoantibodies was useful in diagnosing AIN, thus avoiding unnecessary investigations. Continuous treatment with G‐CSF was not necessary for prophylaxis, even if neutrophil counts were extremely low.