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- Flesch, BK, et al.
(author)
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Multicenter Study on Differential Human Neutrophil Antigen 2 Expression and Underlying Molecular Mechanisms
- 2020
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In: Transfusion medicine and hemotherapy : offizielles Organ der Deutschen Gesellschaft fur Transfusionsmedizin und Immunhamatologie. - : S. Karger AG. - 1660-3796. ; 47:5, s. 385-395
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Journal article (peer-reviewed)abstract
- <b><i>Background:</i></b> The human neutrophil antigen 2 (HNA-2), which is expressed on CD177, is undetectable in 3–5% of the normal population. Exposure of these HNA-2<sub>null</sub> individuals to HNA-2-positive cells can cause immunization and production of HNA-2 antibodies, which can induce immune neutropenia and transfusion-related acute lung injury. In HNA-2-positive individuals, neutrophils are divided into a CD177<sup>pos.</sup> and a CD177<sup>neg.</sup> subpopulation. The molecular background of HNA-2 deficiency and the bimodal expression pattern, however, are not completely decoded. <b><i>Study Design:</i></b> An international collaboration was conducted on the genetic analysis of HNA-2-phenotyped blood samples, including HNA-2-deficient individuals, mothers, and the respective children with neonatal immune neutropenia and regular blood donors. <b><i>Results:</i></b> From a total of 54 HNA-2<sub>null</sub> individuals, 43 were homozygous for the <i>CD177</i>*<i>787A>T</i> substitution. Six carried the <i>CD177</i>*<i>c.1291G>A</i> single nucleotide polymorphism. All HNA-2-positive samples with >40% CD177<sup>pos.</sup> neutrophils carried the *<i>787A</i> wild-type allele, whereas a lower rate of CD177<sup>pos.</sup> neutrophils was preferentially associated with *<i>c.787AT</i> heterozygosity. Interestingly, only the *<i>c.787A</i> allele sequence was detected in complementary DNA (cDNA) sequence analysis carried out on all *<i>c.787AT</i> heterozygous individuals. However, cDNA analysis after sorting of CD177<sup>pos.</sup> and CD177<sup>neg.</sup> neutrophil subsets from HNA-2-positive individuals showed identical sequences, which makes regulatory elements within the promoter unlikely to affect <i>CD177</i> gene transcription in different CD177 neutrophil subsets. <b><i>Conclusion:</i></b> This comprehensive study clearly demonstrates the impact of single nucleotide polymorphisms on the expression of HNA-2 on the neutrophil surface but challenges the hypothesis of regulatory epigenetic effects being implicated in the bimodal CD177 expression pattern.
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