CD19 is a CD molecule expressed on B cells (i.e., B lymphocytes), belonging to the Ig superfamily. All B cell lines except plasma cells, malignant B cells, and FDC express this molecule. It plays a crucial role as a membrane antigen in B cell proliferation, differentiation, activation, and antibody production, and can also facilitate signal transduction of the BCR.
CD19 is expressed in the majority of acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), and B cell lymphomas. In fact, 80% of ALL, 88% of B cell lymphomas, and 100% of B cell leukemias express CD19 normally at high levels. Conversely, other B cell malignancies show lower levels of CD19.
CD19 has been identified as a potential therapeutic target for lymphomas and leukemias. Various immunotherapy methods targeting CD19, such as bispecific antibodies, ADCs, Fc-engineered antibodies, and CAR-T cells, have shown promising results in clinical trials.
