Anti-Human CD19 (Clone 4G7) - FITC (C987-GRP)

CD19 is a B cell surface glycoprotein that is a member of the immunoglobulin (Ig) superfamily1, 2. CD19 is a positive regulator of B cell differentiation that also acts as a bridge between the innate and adaptive immune responses 2. Additionally, CD19 enhances B cell receptor signaling and tumor cell proliferation 11. B cell differentiation occurs in the bone marrow and follows a progression from hematopoietic stem cells to ProB, PreB, and then immature B lymphocytes3. The progression involves multiple gene rearrangements that are carefully controlled and results in the generation of the basic Ig repertoire and expression of various surface molecules, including CD34, CD10, and CD19 3, which forms a complex with Leu13, CD81, and CD21 on the surface of mature B cells 2. Additionally, CD19 associates with the B cell antigen receptor to enhance signal transduction 2. CD19 is an attractive immunotherapy target for cancers of lymphoid origin due to its early and persistent expression throughout B cell maturation4. 4G7 was generated by immunizing a mouse with chronic lymphocytic leukemia cells 5. The antibody is specific for normal and malignant B lymphocytes. 4G7 has been used to analyze CD19 variants for the development of improved CD19 CAR T cell immunotherapy 6 and for fine mapping of the binding epitope 7. The 4G7 epitope is conformationally sensitive and is not accessible on wildtype CD19 when displayed on yeast cells 7 but is available on a mutated variant, CD19.1 6. The 4G7 epitope centers around residue R144, and the hot spot for impactful mutations lies between residues 138 and 153. Additionally, a properly folded extracellular domain is required for 4G7 binding. A single chain Fv fragment of 4G7 has also been tested for bispecific CD19 immunotherapy development 8, 9.