A CD33-specific single-chain immunotoxin mediates potent apoptosis of cultured human myeloid leukaemia cells

Br J Haematol. 2006 Apr;133(2):141-51. doi: 10.1111/j.1365-2141.2005.05869.x.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADP Ribose Transferases / pharmacology*
  • Animals
  • Antigens, CD / immunology*
  • Antigens, Differentiation, Myelomonocytic / immunology*
  • Antigens, Neoplasm / immunology
  • Antineoplastic Agents / pharmacology*
  • Apoptosis / drug effects
  • Bacterial Toxins / pharmacology*
  • Cytotoxicity, Immunologic
  • Epitopes
  • Exotoxins / pharmacology*
  • Flow Cytometry
  • Humans
  • Immunoglobulin Fragments / immunology
  • Immunoglobulin Variable Region / immunology
  • Immunotoxins / pharmacology*
  • Leukemia, Myeloid / immunology
  • Leukemia, Myeloid / pathology*
  • Mice
  • Mice, Inbred BALB C
  • Pseudomonas aeruginosa Exotoxin A
  • Recombinant Fusion Proteins / pharmacology
  • Sialic Acid Binding Ig-like Lectin 3
  • Tumor Cells, Cultured
  • U937 Cells
  • Virulence Factors / pharmacology*

Substances

  • Antigens, CD
  • Antigens, Differentiation, Myelomonocytic
  • Antigens, Neoplasm
  • Antineoplastic Agents
  • Bacterial Toxins
  • CD33 protein, human
  • Cd33 protein, mouse
  • Epitopes
  • Exotoxins
  • Immunoglobulin Fragments
  • Immunoglobulin Variable Region
  • Immunotoxins
  • Recombinant Fusion Proteins
  • Sialic Acid Binding Ig-like Lectin 3
  • Virulence Factors
  • immunoglobulin Fv
  • ADP Ribose Transferases