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.