title: Expression of MUC-1 epitopes on normal bone marrow: implications for the detection of micrometastatic tumor cells.
abstract: OBJECTIVE
  The expression of the carcinoma-associated mucin MUC-1 is thought to be restricted to epithelial cells and is used for micrometastatic tumor cell detection in patients with solid tumors, including those with breast cancer. Little is known, however, about the expression of MUC-1 epitopes in normal hematopoietic cells.
  
  
  METHODS
  MUC-1 expression was analyzed by flow cytometry and immunocytology on bone marrow (BM) mononuclear cells and purified CD34+ cells from healthy volunteers, using different anti-MUC-1-specific monoclonal antibodies. In addition, Western blotting of MUC-1 proteins was performed.
  
  
  RESULTS
  Surprisingly, 2% to 10% of normal human BM mononuclear cells expressed MUC-1, as defined by the anti-MUC-1 antibodies BM-2 (2E11), BM-7, 12H12, MAM-6, and HMFG-1. In contrast, two antibodies recognizing the BM-8 and the HMFG-2 epitopes of MUC-1 were not detected. MUC-1+ cells from normal BM consisted primarily of erythroblasts and normoblasts. In agreement with this, normal CD34+ cells cultured in vitro to differentiate into the erythroid lineage showed a strong MUC-1 expression on day 7 proerythroblasts. Western blotting of these cells confirmed that the reactive species is the known high molecular weight MUC-1 protein.
  
  
  CONCLUSIONS
  Our data demonstrate that some MUC-1 epitopes are expressed on normal BM cells and particularly on cells of the erythroid lineage. Hence the application of anti-MUC-1 antibodies for disseminated tumor cell detection in BM or peripheral blood progenitor cells may provide false-positive results, and only carefully evaluated anti-MUC-1 antibodies (eg, HMFG-2) might be selected. Furthermore, MUC-1-targeted immunotherapy in cancer patients might be hampered by the suppression of erythropoiesis.
authors.affiliation: Department of Hematology, Oncology and Immunology, Eberhard-Karls University of Tübingen, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Brugger
authors.forename: H J
authors.initials: HJ
authors.lastname: Bühring
authors.forename: F
authors.initials: F
authors.lastname: Grünebach
authors.forename: W
authors.initials: W
authors.lastname: Vogel
authors.forename: S
authors.initials: S
authors.lastname: Kaul
authors.forename: R
authors.initials: R
authors.lastname: Müller
authors.forename: T H
authors.initials: TH
authors.lastname: Brümmendorf
authors.forename: B L
authors.initials: BL
authors.lastname: Ziegler
authors.forename: I
authors.initials: I
authors.lastname: Rappold
authors.forename: P
authors.initials: P
authors.lastname: Brossart
authors.forename: S
authors.initials: S
authors.lastname: Scheding
authors.forename: L
authors.initials: L
authors.lastname: Kanz
mesh_terms: D000911:Antibodies, Monoclonal; D001853:Bone Marrow / Q000276:immunology*; D000939:Epitopes / Q000032:analysis*; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000276:immunology*; D006801:Humans; D018396:Mucin-1 / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D018396:Mucin-1