B-cell antigen CD19 (CD19)

B-cell antigen CD19 is a 95 kDa type I transmembrane glycoprotein belonging to the immunoglobulin superfamily that is expressed exclusively on the surface of B-lineage cells from the early pre-B cell stage until terminal differentiation into plasma cells. It serves as a critical co-receptor for the B-cell antigen receptor (BCR) complex, significantly lowering the threshold for antigen-dependent B-cell activation and mediating downstream signaling through the recruitment of kinases such as PI3K and Lyn. Because CD19 is highly and consistently expressed in the majority of B-cell malignancies, including acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphomas, but is absent from hematopoietic stem cells and non-lymphoid tissues, it has become a premier target for immunotherapy. The ExaCAR-NK construct is a specialized chimeric antigen receptor engineered into natural killer cells designed to recognize and eliminate CD19-positive tumor cells. Therapeutic engagement of CD19 via CAR-based technologies has revolutionized the treatment of refractory B-cell cancers, though it requires careful management of side effects such as B-cell aplasia and cytokine-related toxicities.

Other names

B-lymphocyte antigen CD19B-lymphocyte surface antigen B4T-cell surface antigen Leu-12CVID3

The ExaCAR-NK construct utilizes a chimeric antigen receptor (CAR) expressed on natural killer (NK) cells to specifically bind to CD19 on the surface of B-cell malignancies. Upon binding, the CAR-NK cells are activated to release cytotoxic granules (perforin and granzymes) and cytokines, leading to the direct lysis and apoptosis of the target tumor cells.