Neutrophil
alloantigens are involved in a variety of clinical conditions including immune
neutropenias,
transfusion-related acute lung injury (
TRALI), refractoriness to granulocyte transfusions and febrile
transfusion reactions. In the last decade, considerable progress has been made in the characterization of the implicated
antigens. Currently, seven
antigens are assigned to five human neutrophil
antigen (HNA) systems. The HNA-1a, HNA-1b and HNA-1c
antigens have been identified as polymorphic forms of the neutrophil Fcgamma receptor IIIb (CD16b), encoded by three alleles. Recently, the primary structure of the HNA-2a
antigen was elucidated and the HNA-2a-bearing
glycoprotein was identified as a member of the Ly-6/uPAR superfamily, which has been clustered as CD177. The HNA-3a
antigen is located on a 70-95 kDa
glycoprotein; however, its molecular basis is still unknown. Finally, the HNA-4a and HNA-5a
antigens were found to be caused by single
nucleotide mutations in the alphaM (CD11b) and alphaL (CD11a) subunits of the leucocyte adhesion molecules (beta2
integrins). Molecular and biochemical characterization of neutrophil antigenshave expanded our diagnostic tools by the introduction of genotyping techniques and immunoassays for antibody identification. Further studies in the field of neutrophil immunology will facilitate the prevention and management of
transfusion reactions and
immune diseases caused by neutrophil
antibodies.