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Updated: Jul 7, 2026

In Vitro Methods for Comparing Target Binding and CDC Induction Between Therapeutic Antibodies: Applications in Biosimilarity Analysis
Published on: May 4, 2017
Complement-dependent and complement-independent cytotoxicity of polyclonal antithymocyte globulins in chronic
Francis A Ayuk1, Nabil Atassi, Gunther Schuch
1Department of Bone Marrow Transplantation, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. ayuketan@uke.uni-hamburg.de
Objective:
Despite important progress in its management, chronic lymphocytic leukemia (CLL) remains incurable with standard therapies. Allogeneic stem cell transplantation (SCT) is a potentially curative therapy for patients with CLL. Polyclonal antithymocyte (or anti-T-cell) globulins (ATGs) are used for conditioning in allogeneic SCT mainly due to their anti-T-cell activity. ATGs however, contain antibodies targeting antigens expressed on various hematopoietic cells including B cells.
Methods:
We assessed anti-CLL activity of two commercially available ATG preparations at clinically relevant concentrations (10-100 microg/ml) in CLL samples from 16 patients. Cytotoxicity was determined by staining with 7-amino-actinomycin D (7-AAD), annexin V and flow cytometry.
Results:
Both ATG preparations induced marked complement-independent dose-dependent cytotoxicity in all samples. Addition of complement strongly enhanced the cytotoxic effect of both ATG preparations significantly. ATG-induced complement-dependent cytotoxicity (CDC) was at least as high as that observed with Alemtuzumab. Both ATGs enhanced the cytotoxic effect of Fludarabine.
Conclusion:
ATG is an effective agent against CLL in vitro. We suggest that this potential be taken into consideration when developing stem cell transplantation protocols for patients with CLL.
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