CD19 monoclonal antibodies 

CD19 monoclonal antibodies work by targeting the CD19 protein that is present on the surface of pre-B and mature B lymphocytes and overexpressed in several different cancers, including CD19-positive B-cell leukemias or lymphomas.

CD19 monoclonal antibodies may have slightly different ways of working. Some are considered bispecific T-cell engagers, and work by directing T-cells (an important part of our immune system) to target and bind with the CD19 protein that is present on CD19-positive B-cell leukemia or lymphoma cells. Others bind directly to the CD19 antigen and mediate the disintegration and rupture of the B-cell (also called B-cell lysis). 

CD19 is a type-I transmembrane glycoprotein of 95 kDa that belongs to the immunoglobulin superfamily and is widely expressed on B cells throughout most stages of B-cell differentiation, though its expression is down-regulated during their terminal differentiation to plasma cells.

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.