title: Novel fusion proteins for the antigen-specific staining and elimination of B cell receptor-positive cell populations demonstrated by a tetanus toxoid fragment C (TTC) model antigen.
abstract: BACKGROUND
  In an earlier study we developed a unique strategy allowing us to specifically eliminate antigen-specific murine B cells via their distinct B cell receptors using a new class of fusion proteins. In the present work we elaborated our idea to demonstrate the feasibility of specifically addressing and eliminating human memory B cells.
  
  
  RESULTS
  The present study reveals efficient adaptation of the general approach to selectively target and eradicate human memory B cells. In order to demonstrate the feasibility we engineered a fusion protein following the principle of recombinant immunotoxins by combining a model antigen (tetanus toxoid fragment C, TTC) for B cell receptor targeting and a truncated version of Pseudomonas aeruginosa exotoxin A (ETA') to induce apoptosis after cellular uptake. The TTC-ETA' fusion protein not only selectively bound to a TTC-reactive murine B cell hybridoma cell line in vitro but also to freshly isolated human memory B cells from immunized donors ex vivo. Specific toxicity was confirmed on an antigen-specific population of human CD27(+) memory B cells.
  
  
  CONCLUSIONS
  This protein engineering strategy can be used as a generalized platform approach for the construction of therapeutic fusion proteins with disease-relevant antigens as B cell receptor-binding domains, offering a promising approach for the specific depletion of autoreactive B-lymphocytes in B cell-driven autoimmune diseases.
authors.affiliation: Department of Experimental Medicine and Immunotherapy, Institute for Applied Medical Engineering, University Hospital RWTH Aachen, Pauwelsstr. 20, 52074, Aachen, Germany. diana.klose@ime.fraunhofer.de.|Department of Pharmaceutical Product Development, Fraunhofer-Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstr. 6, 52074, Aachen, Germany. diana.klose@ime.fraunhofer.de.
authors.forename: Diana
authors.initials: D
authors.lastname: Klose
authors.affiliation: Department of Internal Medicine D, Rheumatology and Clinical Immunology Unit, University Hospital Münster, Domagkstr. 3, 48149, Münster, Germany. ute.saunders@ukmuenster.de.
authors.forename: Ute
authors.initials: U
authors.lastname: Saunders
authors.affiliation: Department of Experimental Medicine and Immunotherapy, Institute for Applied Medical Engineering, University Hospital RWTH Aachen, Pauwelsstr. 20, 52074, Aachen, Germany. stefan.barth@uct.ac.za.|South African Research Chair in Cancer Biotechnology, Institute of Infectious Disease and Molecular Medicine (IDM), Department of Integrative Biomedical Sciences, Faculty of Health Sciences, University of Cape Town, Anzio Road, 7925, Observatory, South Africa. stefan.barth@uct.ac.za.
authors.forename: Stefan
authors.initials: S
authors.lastname: Barth
authors.affiliation: Department of Pharmaceutical Product Development, Fraunhofer-Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstr. 6, 52074, Aachen, Germany. rainer.fischer@molbiotech.rwth-aachen.de.|Institute for Molecular Biotechnology, RWTH Aachen University, Worringer Weg 1, 52074, Aachen, Germany. rainer.fischer@molbiotech.rwth-aachen.de.
authors.forename: Rainer
authors.initials: R
authors.lastname: Fischer
authors.affiliation: Department of Internal Medicine D, Rheumatology and Clinical Immunology Unit, University Hospital Münster, Domagkstr. 3, 48149, Münster, Germany. a.jacobi@ruppiner-kliniken.de.|Division of Rheumatology and Clinical Immunology, Brandenburg Medical School, Fehrbelliner Str. 38, 16816, Neuruppin, Germany. a.jacobi@ruppiner-kliniken.de.
authors.forename: Annett Marita
authors.initials: AM
authors.lastname: Jacobi
authors.affiliation: Department of Experimental Medicine and Immunotherapy, Institute for Applied Medical Engineering, University Hospital RWTH Aachen, Pauwelsstr. 20, 52074, Aachen, Germany. nachreiner@hia.rwth-aachen.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Nachreiner
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000737:chemistry / Q000378:metabolism; D002478:Cells, Cultured; D004926:Escherichia coli; D057809:HEK293 Cells; D006801:Humans; D006825:Hybridomas / Q000276:immunology / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D051379:Mice; D018448:Models, Immunological; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D013745:Tetanus Toxoid / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
chemical_list: D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D013745:Tetanus Toxoid