title: B-cell reconstitution after lentiviral vector-mediated gene therapy in patients with Wiskott-Aldrich syndrome.
abstract: BACKGROUND
  Wiskott-Aldrich syndrome (WAS) is a severe X-linked immunodeficiency characterized by microthrombocytopenia, eczema, recurrent infections, and susceptibility to autoimmunity and lymphomas. Hematopoietic stem cell transplantation is the treatment of choice; however, administration of WAS gene-corrected autologous hematopoietic stem cells has been demonstrated as a feasible alternative therapeutic approach.
  
  
  OBJECTIVE
  Because B-cell homeostasis is perturbed in patients with WAS and restoration of immune competence is one of the main therapeutic goals, we have evaluated reconstitution of the B-cell compartment in 4 patients who received autologous hematopoietic stem cells transduced with lentiviral vector after a reduced-intensity conditioning regimen combined with anti-CD20 administration.
  
  
  METHODS
  We evaluated B-cell counts, B-cell subset distribution, B cell-activating factor and immunoglobulin levels, and autoantibody production before and after gene therapy (GT). WAS gene transfer in B cells was assessed by measuring vector copy numbers and expression of Wiskott-Aldrich syndrome protein.
  
  
  RESULTS
  After lentiviral vector-mediated GT, the number of transduced B cells progressively increased in the peripheral blood of all patients. Lentiviral vector-transduced progenitor cells were able to repopulate the B-cell compartment with a normal distribution of B-cell subsets both in bone marrow and the periphery, showing a WAS protein expression profile similar to that of healthy donors. In addition, after GT, we observed a normalized frequency of autoimmune-associated CD19(+)CD21(-)CD35(-) and CD21(low) B cells and a reduction in B cell-activating factor levels. Immunoglobulin serum levels and autoantibody production improved in all treated patients.
  
  
  CONCLUSIONS
  We provide evidence that lentiviral vector-mediated GT induces transgene expression in the B-cell compartment, resulting in ameliorated B-cell development and functionality and contributing to immunologic improvement in patients with WAS.
authors: San Raffaele Telethon Institute for Gene Therapy (TIGET), IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors: Maria Carmina
authors: MC
authors: Castiello
authors: San Raffaele Telethon Institute for Gene Therapy (TIGET), IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors: Samantha
authors: S
authors: Scaramuzza
authors: San Raffaele Telethon Institute for Gene Therapy (TIGET), IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors: Francesca
authors: F
authors: Pala
authors: Pediatric Immunohematology and Bone Marrow Transplantation Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors: Francesca
authors: F
authors: Ferrua
authors: CRS4, Science and Technology Park Polaris, Pula, Cagliari, Italy.
authors: Paolo
authors: P
authors: Uva
authors: San Raffaele Telethon Institute for Gene Therapy (TIGET), IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors: Immacolata
authors: I
authors: Brigida
authors: San Raffaele Telethon Institute for Gene Therapy (TIGET), IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors: Lucia
authors: L
authors: Sereni
authors: Department of Immunology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands.
authors: Mirjam
authors: M
authors: van der Burg
authors: Pediatric Immunohematology and Bone Marrow Transplantation Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors: Giorgio
authors: G
authors: Ottaviano
authors: Dr von Hauner Children's Hospital, Ludwig-Maximilians-University Munich, Munich, Germany.
authors: Michael H
authors: MH
authors: Albert
authors: San Raffaele Telethon Institute for Gene Therapy (TIGET), IRCCS San Raffaele Scientific Institute, Milan, Italy; Vita-Salute San Raffaele University, Milan, Italy.
authors: Maria
authors: M
authors: Grazia Roncarolo
authors: San Raffaele Telethon Institute for Gene Therapy (TIGET), IRCCS San Raffaele Scientific Institute, Milan, Italy; Vita-Salute San Raffaele University, Milan, Italy.
authors: Luigi
authors: L
authors: Naldini
authors: San Raffaele Telethon Institute for Gene Therapy (TIGET), IRCCS San Raffaele Scientific Institute, Milan, Italy; Department of System Medicine, Tor Vergata University, Rome, Italy.
authors: Alessandro
authors: A
authors: Aiuti
authors: San Raffaele Telethon Institute for Gene Therapy (TIGET), IRCCS San Raffaele Scientific Institute, Milan, Italy; IRGB CNR, Milan Unit, Milan, Italy. Electronic address: villa.anna@hsr.it.
authors: Anna
authors: A
authors: Villa
authors: San Raffaele Telethon Institute for Gene Therapy (TIGET), IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors: Marita
authors: M
authors: Bosticardo
mesh_terms: D001323:Autoantibodies / Q000096:biosynthesis; D053264:B-Cell Activating Factor / Q000235:genetics / Q000378:metabolism; D016175:B-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D001853:Bone Marrow / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D015870:Gene Expression; D020869:Gene Expression Profiling; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007136:Immunoglobulins / Q000096:biosynthesis; D016130:Immunophenotyping; D007223:Infant; D016086:Lentivirus / Q000235:genetics; D008297:Male; D011993:Recombinant Fusion Proteins / Q000627:therapeutic use; D014161:Transduction, Genetic; D019172:Transplantation Conditioning; D014182:Transplantation, Autologous; D014923:Wiskott-Aldrich Syndrome / Q000235:genetics / Q000276:immunology / Q000473:pathology / Q000628:therapy*; D051316:Wiskott-Aldrich Syndrome Protein / Q000235:genetics* / Q000276:immunology
chemical_list: D001323:Autoantibodies; D053264:B-Cell Activating Factor; D007136:Immunoglobulins; D011993:Recombinant Fusion Proteins; C495767:WAS protein, human; D051316:Wiskott-Aldrich Syndrome Protein; C555620:anti-CD20Fab-LDM protein
keywords: B cell; Wiskott-Aldrich syndrome; gene therapy; lentiviral vector; primary immunodeficiency