title: A CD33-specific single-chain immunotoxin mediates potent apoptosis of cultured human myeloid leukaemia cells.
abstract: A novel single-chain immunotoxin was constructed by combining a CD33-specific single chain Fv (scFv) antibody fragment with an engineered variant of Pseudomonas exotoxin A (ETA). The variant toxin carries the KDEL peptide at its C-terminus, a cellular peptide mediating improved retrograde transport to the endoplasmic reticulum. The purified recombinant fusion protein induced potent apoptosis of the human myeloid cell lines U937, HL-60 and THP-1. Up to 98% of U937 cells were eliminated after treatment for 72 h with a single dose of 500 ng/ml (c. 7 nmol/l). Killing was antigen-specific and occurred by apoptosis. A control protein, consisting of a CD19-specific scFv antibody fragment fused to the ETA-KDEL toxin, failed to induce death of the CD19-negative cell lines U937, HL-60 and THP-1. The CD33-ETA toxin also mediated apoptosis of fresh patient-derived acute myeloid leukaemia cells from bone marrow and peripheral blood. The pronounced antigen-restricted cytotoxicity of the novel fusion protein makes it a candidate for further evaluation of its therapeutic potential.
authors.affiliation: University of Erlangen-Nuremberg, Erwin-Rommel-Strasse 3, D-91058 Erlangen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schwemmlein
authors.forename: Matthias
authors.initials: M
authors.lastname: Peipp
authors.forename: Karin
authors.initials: K
authors.lastname: Barbin
authors.forename: Domenica
authors.initials: D
authors.lastname: Saul
authors.forename: Bernhard
authors.initials: B
authors.lastname: Stockmeyer
authors.forename: Roland
authors.initials: R
authors.lastname: Repp
authors.forename: Josef
authors.initials: J
authors.lastname: Birkmann
authors.forename: Fuat
authors.initials: F
authors.lastname: Oduncu
authors.forename: Bertold
authors.initials: B
authors.lastname: Emmerich
authors.forename: Georg H
authors.initials: GH
authors.lastname: Fey
mesh_terms: D036002:ADP Ribose Transferases / Q000494:pharmacology*; D000818:Animals; D015703:Antigens, CD / Q000276:immunology*; D015214:Antigens, Differentiation, Myelomonocytic / Q000276:immunology*; D000951:Antigens, Neoplasm / Q000276:immunology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001427:Bacterial Toxins / Q000494:pharmacology*; D003602:Cytotoxicity, Immunologic; D000939:Epitopes; D005098:Exotoxins / Q000494:pharmacology*; D005434:Flow Cytometry; D006801:Humans; D007128:Immunoglobulin Fragments / Q000276:immunology; D007135:Immunoglobulin Variable Region / Q000276:immunology; D000922:Immunotoxins / Q000494:pharmacology*; D007951:Leukemia, Myeloid / Q000276:immunology / Q000473:pathology*; D051379:Mice; D008807:Mice, Inbred BALB C; D011993:Recombinant Fusion Proteins / Q000494:pharmacology; D063268:Sialic Acid Binding Ig-like Lectin 3; D014407:Tumor Cells, Cultured; D020298:U937 Cells; D037521:Virulence Factors / Q000494:pharmacology*; D000097668:Pseudomonas aeruginosa Exotoxin A
chemical_list: D036002:ADP Ribose Transferases; D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; D001427:Bacterial Toxins; D000939:Epitopes; D005098:Exotoxins; D007128:Immunoglobulin Fragments; D007135:Immunoglobulin Variable Region; D000922:Immunotoxins; D011993:Recombinant Fusion Proteins; D063268:Sialic Acid Binding Ig-like Lectin 3; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A; C571163:CD33 protein, human; C571165:Cd33 protein, mouse; C055966:immunoglobulin Fv