Characterization of Seven Low Incidence Blood Group Antigens Carried by Erythrocyte Band 3 Protein

Abstract

Recent studies have demonstrated that band 3 carries antigens of the Diego blood group system and have elucidated the molecular basis of several previously unassigned low incidence and high incidence antigens. Because the available serological data suggested that band 3 may carry additional low incidence blood group antigens, we screened band 3 genomic DNA encoding the membrane domain of band 3 for single-strand conformational polymorphisms. We found that the putative first ectoplasmic loop of band 3 carries blood group antigen ELO, 432 Arg→Trp; the third putative loop harbors antigens Vga (Van Vugt), 555 Tyr→His, BOW 561 Pro→Ser, Wu (Wulfsberg), 565 Gly→Ala, and Bpa (Bishop), 569 Asn→Lys; and the putative fourth ectoplasmic loop carries antigens Hga (Hughes), 656 Arg→Cys, and Moa (Moen), 656 Arg→His. We studied erythrocytes from carriers of five of these blood group antigens. We found similar levels of reticulocyte mRNA corresponding to the two band 3 gene alleles, normal content and glycosylation of band 3 in the red blood cell membrane, and normal band 3-mediated sulfate influx into red blood cells, suggesting that the mutations do not have major effect on band 3 structure and function. In addition to elucidating the molecular basis of seven low incidence blood group antigens, these results help to create a more accurate structural model of band 3.

Genomic coordinates and continental distribution of 120 blood group variants reported by the 1000 Genomes Project

“…However, RBC alloantigenicity depends primarily on residues/modifications exposed to the extracellular milieu, regardless of their role in expression, localization, or function. Many blood group antigenic sites will not be subject to strong evolutionary pressure, as described previously for Diego and Kell . Biochemical differences in amino acid substitutions may also not be as critical for immunohematology, since several proven antigenic variations (Wu/DISK, KEL:‐22, KUCI‐, Co(b+), etc) result from amino acid substitutions that are considered “conservative.” Möller and colleagues filtered variants with extracellular localization for possible antigenicity, and Howe and Stack reported that meta‐SNP scores can be helpful.…”

Human erythrocyte antigens in Brazilian Capuchin monkeys (Sapajus sp.)

“…It is also believed that the Di a antigen takes part of an adhesion complex for malaria parasites ( Plasmodium sp .) on the surface of red blood cells, favoring human infection by these protozoa . Malaria by Plasmodium brasilianum has been reported in Brazilian Capuchin monkeys .…”

Amino acid substitutions in human erythroid protein band 3 account for the low‐incidence antigens NFLD and BOW

“…Characterization of a CCC→TCC mutation in exon 14 of SLC4A1 that gives rise to a Pro561Ser substitution in the third extracellular loop of band 3 defines BOW. Our results are concordant with those of Jarolim et al, 9 and, because of these independent findings, the ISBT Working Party has designated BOW as DI15 and rendered its previous designation (700.46) obsolete 6 . With respect to NFLD, SSCP analysis of SLC4A1 suggested that variation in both exons 12 and 14 might relate to NFLD expression.…”

“…Serologically, NFLD and BOW are well‐characterized 3,4 ; genetically, family studies have excluded NFLD from 10 of the established blood group systems and BOW from 5 of them. The recent expansion of the Diego blood group system 5,6 ; the sensitivity of NFLD and BOW to α‐chymotrypsin 3 ; the serologic relationship 7 among NFLD, BOW, and Wu (DI9) 8,9 ; and preliminary evidence 10 suggesting that NFLD might belong to the Diego blood group system prompted the current investigation.…”

“…In this report, we document the SLC4A1 mutations and corresponding band 3 amino acid substitutions that account for the low‐incidence RBC antigens NFLD and BOW. Our results confirm findings of Jarolim et al 9 with respect to BOW and provide strong evidence that two band 3 amino acid substitutions are required for NFLD expression.…”