Characterization of human FCGR3B*02 (HNA-1b, NA2) cDNAs and IMGT standardized description of FCGR3B alleles

The low-affinity Fc gamma receptor IIIb (Fc gamma RIIIb and CD16b) is constituted by a unique FCGR3B polypeptide chain that comprises two extracellular immunoglobulin-like domains, and is expressed as a glycosylphosphatidyl inositol-anchored receptor on the neutrophils. The FCGR3B chain bears allotypes that define the human neutrophil antigen-1 (HNA-1 and NA) system involved in major post-transfusional reactions. FCGR3B is highly homologous to FCGR3A, which is expressed as a transmembrane receptor on natural killer cells and monocytes/macrophages. Its transcription products were not yet fully characterized. In the present work, we sequenced FCGR3B cDNAs with complete 3' untranslated region from purified granulocytes of HNA-1b/HNA-1b (NA2/NA2) genotyped donors. We characterized two FCGR3B cDNAs of different lengths corresponding to two polyadenylation sites. This result was corroborated by data raised by serial analysis of gene expression (SAGE). FCGR3B allele polymorphisms, from this article [FCGR3B*02 (HNA-1b, NA2)] and from the literature, are described for the first time according to the IMGT standardized nomenclature and to the IMGT unique numbering for C-LIKE-DOMAIN (http://imgt.cines.fr). These rules, described in the IMGT Scientific chart, are based on the IMGT-ONTOLOGY concepts. IMGT allele alignments and IMGT Collier de Perles graphical two-dimensional representations are provided for the two Ig-like domains (or C-LIKE-DOMAINs) [D1] and [D2] of FCGR3B*02. The standardized description of FCGR3B allele polymorphisms was approved by the IMGT Nomenclature Committee (IMGT-NC) and is freely available in IMGT repertoire at IMGT, http://imgt.cines.fr.