title: Increased numbers of circulating hematopoietic stem/progenitor cells are chronically maintained in patients treated with the CD49d blocking antibody natalizumab.
abstract: Blockade of CD49d-mediated lymphocyte trafficking has been used therapeutically for certain autoimmune diseases, such as multiple sclerosis (MS). In addition to negative effects on the trafficking of mature lymphocytes to sites of inflammation, CD49d blockade in mice and monkeys rapidly mobilizes hematopoietic stem/progenitor cells (HSPCs) capable of short- and long-term engraftment. Here we aimed to ascertain the effects of treatment with antifunctional anti-CD49d antibody in humans (MS patients receiving infusions of the CD49d-blocking antibody natalizumab) on levels of circulating HSPCs after a single dose of antibody or after long-term treatment. On average, 6-fold elevated levels of circulating CD34+ cells and colony-forming unit-culture (CFU-C) were achieved within 1 day of the first dose of natalizumab, and similar levels were continuously maintained under monthly natalizumab infusions. The blood of natalizumab-treated subjects also contained SCID-repopulating cells. The fate of these circulating HSPCs and their clinical relevance for MS patients remains to be determined.
authors.affiliation: Department of Medicine/Hematology, University of Washington, Seattle, USA. hbonig@u.washington.edu
authors.forename: Halvard
authors.initials: H
authors.lastname: Bonig
authors.forename: Annette
authors.initials: A
authors.lastname: Wundes
authors.forename: Kai-Hsin
authors.initials: KH
authors.lastname: Chang
authors.forename: Sylvia
authors.initials: S
authors.lastname: Lucas
authors.forename: Thalia
authors.initials: T
authors.lastname: Papayannopoulou
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage* / Q000276:immunology; D061067:Antibodies, Monoclonal, Humanized; D018952:Antigens, CD34 / Q000276:immunology; D003114:Colony-Forming Units Assay; D004305:Dose-Response Relationship, Drug; D005260:Female; D000882:Haplorhini; D019650:Hematopoietic Stem Cell Mobilization; D006412:Hematopoietic Stem Cells / Q000276:immunology; D006801:Humans; D007249:Inflammation / Q000097:blood / Q000188:drug therapy / Q000276:immunology; D039441:Integrin alpha4 / Q000276:immunology; D008214:Lymphocytes / Q000276:immunology; D008297:Male; D051379:Mice; D016513:Mice, SCID; D009103:Multiple Sclerosis / Q000097:blood / Q000188:drug therapy* / Q000276:immunology; D000069442:Natalizumab; D013997:Time Factors
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D018952:Antigens, CD34; D000069442:Natalizumab; D039441:Integrin alpha4