Schwemmlein Michael, Peipp Matthias, Barbin Karin, Saul Domenica, Stockmeyer Bernhard, Repp Roland, Birkmann Josef, Oduncu Fuat, Emmerich Bertold, Fey Georg H
University of Erlangen-Nuremberg, Erwin-Rommel-Strasse 3, D-91058 Erlangen, Germany.
Br J Haematol. 2006 Apr;133(2):141-51. doi: 10.1111/j.1365-2141.2005.05869.x.
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.
通过将CD33特异性单链Fv（scFv）抗体片段与工程改造的绿脓杆菌外毒素A（ETA）变体相结合，构建了一种新型单链免疫毒素。该变体毒素在其C末端携带KDEL肽，这是一种介导内质网逆行转运改善的细胞肽。纯化的重组融合蛋白可诱导人髓系细胞系U937、HL-60和THP-1发生强效凋亡。用500 ng/ml（约7 nmol/l）的单剂量处理72小时后，高达98%的U937细胞被清除。杀伤具有抗原特异性，且通过凋亡发生。一种由与ETA-KDEL毒素融合的CD19特异性scFv抗体片段组成的对照蛋白未能诱导CD19阴性细胞系U937、HL-60和THP-1死亡。CD33-ETA毒素还介导了来自骨髓和外周血的新鲜患者来源的急性髓系白血病细胞的凋亡。这种新型融合蛋白显著的抗原限制性细胞毒性使其成为进一步评估其治疗潜力的候选药物。
