Primary autoimmune neutropenia in children in Taiwan

BACKGROUND: Autoimmune neutropenia in children is caused by granulocyte‐specific autoantibodies. These antibodies react to the patient's own neutrophils but disappear when the neutropenia spontaneously remits. This study reviewed our experience with autoimmune neutropenia in children and investigated possible associations with HLA‐DR and HLA‐DQ alleles. STUDY DESIGN AND METHODS: From 1993 to 2006, our laboratory received 155 blood samples from children with neutropenia. Of these samples, 55 had granulocyte‐specific autoantibodies on the indirect granulocyte immunofluorescence test. As the children had no other disorders associated with neutropenia, they were diagnosed with primary autoimmune neutropenia. HLA‐DRB1 and ‐DQB1 allele typing was performed in 31 cases, and the results were compared with those of 190 normal healthy unrelated Taiwanese controls. RESULTS: The mean ages of onset and resolution of neutropenia were 9.8 months (median, 9.0 months; range, 4‐28 months) and 22.5 months (median, 20.0 months; range, 13‐44 months), respectively. The male‐to‐female ratio was 1.2:1. The mean absolute neutrophil count was 190 per µL (standard deviation, 213/µL). Most patients (74%) had antibodies against HNA‐1a. Autoimmune neutropenia in children in Taiwan was significantly associated with HLA‐DQB1*0503 (odds ratio, 6.48; p = 0.0002; pc = 0.003) allele. CONCLUSION: In Taiwan, autoimmune neutropenia in children is associated with HLA‐DQB1*0503. The autoantibody in autoimmune neutropenia is most commonly anti‐HNA‐1a.