title: Onset of expression of the components of the Kell blood group complex.
abstract: BACKGROUND
  Kell and XK, two distinct red blood cell membrane proteins, are linked by a disulfide bond and form the Kell blood group complex. Kell surface antigens are expressed early during erythropoiesis but the onset of expression of XK which carries the Kx antigen is unknown.
  
  
  METHODS
  To determine whether Kell and XK are synchronously expressed, sorted human hematopoietic progenitor cells and mouse progenitor cells of defined lineage were studied. To determine the onset of expression, human marrow and cord blood cells were sorted into three subpopulations, representing stem, multipotent, and erythroid progenitor cells, and the expression of Kell and XK was determined by reverse transcription-polymerase chain reaction (RT-PCR) and fluorescence-activated cell sorting (FACS) analysis. Mouse Kell and XK transcripts were determined by cDNA blotting of progenitor cells of defined lineage.
  
  
  RESULTS
  By RT-PCR, human peripheral blood progenitor cells had weak expression of Kell and XK transcripts but FACS analysis did not detect surface antigens. Kell and XK transcripts are expressed in multipotent progenitor cells and these cells express Kell surface antigens. The expression of Kx antigen in progenitor cells was not determined owing to nonspecific reactions with the antibody. By cDNA blotting, mouse Kell expression was detected in bipotential megakaryocytes-erythroid cells and in colony-forming units-erythroid (CFU-E) and burst-forming units-erythroid (BFU-E), whereas XK was only detected in CFU-E and BFU-E.
  
  
  CONCLUSIONS
  Both Kell and XK transcripts occur early during erythropoiesis; however, expression may not be coincident because, in mice, Kell transcripts, but not XK, occur in bipotential megakaryocytes-erythroid progenitor cells.
authors.affiliation: Lindsley F. Kimball Research Institute of the New York Blood Center, New York, New York 10021, USA.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Pu
authors.forename: Colvin M
authors.initials: CM
authors.lastname: Redman
authors.forename: Jan W M
authors.initials: JW
authors.lastname: Visser
authors.forename: Soohee
authors.initials: S
authors.lastname: Lee
mesh_terms: D026921:Amino Acid Transport Systems, Neutral / Q000097:blood / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000942:Antigens, Bacterial / Q000097:blood / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018952:Antigens, CD34 / Q000378:metabolism; D000954:Antigens, Surface / Q000097:blood / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001789:Blood Group Antigens / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001854:Bone Marrow Cells / Q000276:immunology; D019070:Cell Lineage; D018076:DNA, Complementary; D004220:Disulfides / Q000737:chemistry; D015672:Erythroid Precursor Cells / Q000276:immunology / Q000378:metabolism*; D004920:Erythropoiesis / Q000276:immunology; D005312:Fetal Blood / Q000276:immunology; D006412:Hematopoietic Stem Cells / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007231:Infant, Newborn; D007626:Kell Blood-Group System / Q000097:blood / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008533:Megakaryocytes / Q000378:metabolism; D008565:Membrane Proteins / Q000097:blood / Q000378:metabolism; D051379:Mice
chemical_list: D026921:Amino Acid Transport Systems, Neutral; D000942:Antigens, Bacterial; D018952:Antigens, CD34; D000954:Antigens, Surface; D001789:Blood Group Antigens; D018076:DNA, Complementary; D004220:Disulfides; C030659:K antigens; D007626:Kell Blood-Group System; D008565:Membrane Proteins; C087883:XK protein, human; C498286:Xkh protein, mouse