Genetic variation of the HNA-3a encoding gene

BACKGROUND: Antibodies against the human neutrophil alloantigen-3a (HNA-3a) play an important role in transfusion-related acute lung injury. The HNA-3a and -3b alloantigens result from a single-nucleotide exchange in the choline transporter-like protein 2 gene (CTL2). We sought for additional polymorphisms that might impair antibody binding to or genotyping of the HNA-3a or -3b antigens. STUDY DESIGN AND METHODS: CTL2-specific complementary DNA (cDNA) fragments were generated from 67 unrelated blood donors followed by DNA sequencing. Polymerase chain reaction with sequence-specific primers (PCR-SSP) was used to test a higher number of donors for relevant new single-nucleotide polymorphisms (SNPs). The granulocyte agglutination test recommended for HNA-3a antibody detection was performed to check HNA-3a antibody binding to the products of the CTL-2 gene variants. RESULTS: Two new missense mutations were demonstrated in the CTL2 cDNA: a 537C>T* exchange leading to a Leu153Phe amino acid substitution and a 988C>T variation predicting a Thr301Met change. The inherited 537T variant is located in the HNA-3a allele and results in impaired granulocyte agglutination by four of 14 HNA-3a antibodies tested while the 988T variant remains nearly unaffected. CONCLUSIONS: The Leu153Phe exchange next to the HNA-3a/b defining amino acid position can impede the binding of HNA-3a alloantibodies. The HNA-3a genotyping by PCR-SSP might produce misleading results in HNA-3ab heterozygous individuals with the additional CTL2-537T variation of the HNA-3a antigen. These findings must account for the development of new screening assays.