Epitope Mapping of the Anti-CD20 Monoclonal Antibodies (C20Mab-11 and 2H7) Using HisMAP Method

CD20, which is expressed on B lymphocytes, has been studied as a therapeutic target for B cell lymphomas and autoimmune disorders. Identifying the binding epitopes of monoclonal antibodies (mAbs) can contribute to our understanding of their functions. We have previously developed an anti-CD20 mAb (clone C 20 Mab-11) using a Cell-Based Immunization and Screening (CBIS) method. In this study, we aimed to determine the binding epitopes of anti-CD20 mAbs, such as C 20 Mab-11 and 2H7, using the His-tag insertion for epitope mapping (HisMAP). The results showed that 171 -NPSE- 174 and 168 -EPANPSE- 174 in the second loop of CD20 were essential for C 20 Mab-11 binding and 2H7 binding, respectively. Although we developed many mAbs that recognize conformational epitopes using the CBIS method, there are many difficulties in epitope mapping for these mAbs. HisMAP could be useful for determining the conformational epitopes of other mAbs against membrane proteins.