INTRODUCTION
Chronic benign neutropenia (CBN) of infancy and childhood is characterized by a self-limiting low neutrophil count below 1.5 x 109/L lasting for at least 6 months.(1) The condition encompasses both autoimmune neutropenia (AIN) and chronic idiopathic neutropenia (CIN). There continues to be a confusing overlap in the nomenclature and classification among the immune neutropenia syndromes despite sharing a similar benign clinical course, differing only in the presence or absence of anti-neutrophil antibodies.(2) The difficulty in differentiating the two lies with the variable accuracy and availability of the numerous testing modalities available for antibody detection (3) namely classical tests such as granulocyte agglutination tests (GAT), immunofluorescence tests (GIFT), monoclonal antibody-specific immobilization of granulocyte antigens (MAIGA) and newer bead-based assay such as LABScreen MULTI (One Lamda, Inc). The detection rate of anti-neutrophil antibodies in patients with CBN could be as high as 98-100% when several testing methods are used. (1, 4) According to an earlier cohort study by our group, Chinese children with AIN share similar clinical characteristics with patients of other western series, including the age of onset (9 months) and male to female ratio (4:6).(1, 4, 5) Among the 24 children studied, they all experienced a relatively benign course regardless of their remission status.(5) Whether anti-neutrophil antibody testing plays a role in establishing a diagnosis, predicting outcome or have implications on follow up or management remains controversial, with various studies demonstrating conflicting evidence.(1, 6-8) This prospective study aims to determine the prevalence of anti-neutrophil antibody among a larger group of Chinese children using multiple modalities of testing and whether the presence or absence of antibodies has implications on the clinical characteristics and prognosis of these patients.