Human neutrophil antigen and antibody studies: a Taiwanese experience

Neutrophil alloantibodies are clinically known to cause neonatal neutropenia and transfusion‐related lung injuries. Furthermore, neutrophil autoantibodies are associated with autoimmune neutropenia. This article is a review on neutrophil alloantigen in the Taiwanese population, and case investigations related to allo/auto neutrophil antibodies over a period of 20 years in the immunohaematology reference laboratory of Mackay Memorial Hospital, Taiwan. In Taiwanese populations, HNA‐1a is more frequent than HNA‐1b (90% and 50% respectively) and HNA‐1c is not seen. Furthermore, the FcgRIIIb‐deficient individual homozygous for FCGR3B gene deletion is estimated to be approximately 1 in 180 and is not as rare as previously thought. Although mothers homozygous for either HNA‐1a or HNA‐1b are commonly found in Taiwan, the number of patients with neonatal neutropenia caused by HNA‐1 alloantibodies is seldom seen. In a search among our previous laboratory requests of neonatal cases for granulocyte antibodies testing over a 10‐year period, only four cases showed neutrophil alloantibodies in the mother and baby’s sera. Lastly, primary autoimmune neutropenia among 51 children was retrospectively investigated. The study revealed that the specificity of the autoantibody was most commonly directed against HNA‐1a. In addition, 31 cases were genotyped for HLA‐DRB1 and ‐DQB1 genes. The HLA allele HLA‐DQB1*05:03 was found to be associated with primary autoimmune neutropenia in Taiwan.