Primary autoimmune neutropenia in children: a study of neutrophil antibodies and clinical course

Background and Objectives Primary autoimmune neutropenia (AIN) in children is characterized by severe neutropenia, but mild bacterial infections and a spontaneous resolution. Neutrophil autoantibodies are involved in the disease. The precise relationship between the specificity and level of reactivity of the antibodies with the absolute neutrophil count and frequency of infections is not known. To obtain a better insight into this relationship, we performed a follow-up study in 15 patients with primary AIN. In addition, we performed two different neutrophil antibody tests to evaluate their sensitivity and specificity.

Materials and Methods Blood samples from 15 children were tested for neutrophil antibodies, at different time-points during the disease, by using the indirect granulocyte immunofluorescence test (GIFT) and the monoclonal antibody-specific immobilization of granulocyte antigens (MAIGA) assay. Clinical data related to the occurrence of bacterial infections and treatment, and neutrophil counts were collected.

Results Early in the disease, antibodies with pan-FcRIIIb specificity were detected, and HNA-1a or HNA-1b specificity of the antibodies developed over time. The sensitivity and specificity of neutrophil antibody detection tests were higher in the GIFT than in the MAIGA assay. Variables predicting time of recovery from neutropenia were not found. Prophylactic antibiotics led to the almost complete disappearance of infections.

Conclusions In patients with primary neutropenia, neutrophil antibody specificity changes over time. Prophylactic antibiotics do benefit the patients.