fa Medical Biotechnology Medical Biotechnology مقاله کامل Full Length/Original Article <strong>Background: </strong>Ofatumumab, an anti-CD20 mAb, was approved in 2009 for the treatment of chronic lymphocytic leukemia. This mAb acts through immune-mediated mechanisms, in particular complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity by natural killer cells as well as antibody-dependent phagocytosis by macrophages. Apoptosis induction is another mechanism of this antibody. Computational docking is the method of predicting the conformation of an antibody-antigen from its separated elements. Validation of the designed antibodies is carried out by docking tools. Increased affinity enhances the biological action of the antibody, which in turn improves the therapeutic effects. Furthermore, the increased antibody affinity can reduce the therapeutic dose of the antibody, resulting in lower toxicity and handling cost. <strong>Methods:</strong> Considering the importance of this issue, using <em>in silico</em> analysis such as docking and molecular dynamics, we aimed to find the important amino acids of the Ofatumumab antibody and then replaced these amino acids&nbsp;with others to improve antibody-binding affinity. Finally, we examined the binding affinity of&nbsp;antibody variants to antigen. <strong>Results</strong>: Our findings showed that variant 3 mutations have improved the characteristics of antibody binding compared to normal Ofatumumab antibodies. &nbsp;<strong>Conclusion:</strong> The designed anti-CD20 antibodies showed potentiality for improved affinity in comparison to commercial Ofatumumab.&nbsp; Monoclonal antibody, Ofatumumab, Protein engineering 180 192 http://ibj.pasteur.ac.ir/browse.php?a_code=A-10-1-695&slc_lang=fa&sid=1 Zahra Payandeh No Department of Medical Biotechnology and Nanotechnology, Faculty of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran Masoumeh Rajabibazl Yes Department of Clinical Biochemistry, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran Yousef Mortazavi No Department of Medical Biotechnology and Nanotechnology, Faculty of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran Azam Rahimpour No School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran Amir Hossein Taromchi No Department of Medical Biotechnology and Nanotechnology, Faculty of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran