title: Blood group A(1) and A(2) revisited: an immunochemical analysis.
abstract: OBJECTIVE
  The basis of blood group A(1) and A(2) phenotypes has been debated for many decades, and still the chemical basis is unresolved. The literature generally identifies the glycolipid chemical differences between blood group A(1) and A(2) phenotypes as being poor or no expression of A type 3 and A type 4 structures on A(2) red cells, although this assertion is not unanimous.
  
  
  METHODS
  Using purified glycolipids and specific monoclonal antibodies, we revisited the glycolipid basis of the A(1) and A(2) phenotypes. Purified glycolipids were extracted from four individual A(1) and four individual A(2) blood units. One blood unit from an A weak subgroup was also included. Monoclonal anti-A reagents including those originally used to define the basis of A(1) and A(2) phenotypes were used in a thin layer chromatography - enzyme immunoassay to identify the presence of specific glycolipids.
  
  
  RESULTS
  A type 3 glycolipid structures were found to be present in large amounts in all phenotypes. In contrast, the A type 4 glycolipid structure was virtually undetectable in the A(2) phenotype, but was present in the A(1) and A subgroup samples.
  
  
  CONCLUSIONS
  The major glycolipid difference between the A(1) and A(2) phenotypes is the dominance of A type 4 glycolipids in the A(1) phenotype.
authors.affiliation: Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska University Hospital, Göteborg University, Gothenburg, Sweden. lola.svensson@gu.se
authors.forename: L
authors.initials: L
authors.lastname: Svensson
authors.forename: L
authors.initials: L
authors.lastname: Rydberg
authors.forename: L C
authors.initials: LC
authors.lastname: de Mattos
authors.forename: S M
authors.initials: SM
authors.lastname: Henry
mesh_terms: D000017:ABO Blood-Group System / Q000145:classification* / Q000276:immunology / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000276:immunology; D000918:Antibody Specificity; D002855:Chromatography, Thin Layer; D000939:Epitopes / Q000737:chemistry / Q000276:immunology; D005647:Fucosyltransferases / Q000235:genetics; D006017:Glycolipids / Q000737:chemistry* / Q000276:immunology / Q000302:isolation & purification; D006801:Humans; D007124:Immunoenzyme Techniques; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D007983:Lewis Blood Group Antigens / Q000235:genetics; D017350:N-Acetylgalactosaminyltransferases / Q000235:genetics / Q000378:metabolism; D009844:Oligosaccharides / Q000737:chemistry* / Q000276:immunology; D025942:Oligosaccharides, Branched-Chain; D010641:Phenotype; D000097631:Galactoside 2-alpha-L-fucosyltransferase
chemical_list: D000017:ABO Blood-Group System; D000911:Antibodies, Monoclonal; D000939:Epitopes; D005647:Fucosyltransferases; D006017:Glycolipids; D007527:Isoenzymes; D007983:Lewis Blood Group Antigens; D017350:N-Acetylgalactosaminyltransferases; D009844:Oligosaccharides; D025942:Oligosaccharides, Branched-Chain; D000097631:Galactoside 2-alpha-L-fucosyltransferase; C101335:blood group A trisaccharide; C003742:UDPgalactosamine-galactose acetylgalactosaminyltransferase