A monoclonal antibody directed against human CD20 with potential antineoplastic activity. Anti-CD20 monoclonal antibody TL011 specifically binds to the B cell-specific cell surface antigen CD20 antigen (MS4A1; membrane-spanning 4-domains, subfamily A, member 1), thereby potentially triggering an immune response against CD20-positive B cells, leading to B cell apoptosis. CD20 is a non-glycosylated cell surface phosphoprotein that is exclusively expressed on B cells during most stages of B cell development and is often overexpressed in B-cell malignancies.