CD19 His Tag Protein, Cynomolgus/Rhesus macaque

CD19 (Cluster of Differentiation 19) is a 95 kDa type I transmembrane glycoprotein belonging to the immunoglobulin superfamily, encoded by the CD19 gene located on the short arm of chromosome 16 (16p11.2). It serves as a lineage-specific B cell marker, expressed continuously from the pro-B cell stage until its downregulation prior to terminal differentiation into plasma cells. Structurally, CD19 comprises two extracellular Ig-like domains (C2 type), a transmembrane region, and an intracellular domain containing multiple tyrosine residues that interact with Src family kinases (such as Lyn and Fyn) and the PI3K/AKT signaling pathway. Functioning as a co-receptor for the B cell receptor (BCR), CD19 lowers the threshold for B cell activation and enhances antigen responsiveness, playing essential roles in B cell development, proliferation, differentiation, and antibody production. Under pathological conditions, CD19 is highly expressed in the vast majority of B cell malignancies (including B-ALL, diffuse large B cell lymphoma, and follicular lymphoma), making it an ideal target for immunotherapy. Chimeric antigen receptor T cell (CAR-T) therapies (such as Tisagenlecleucel and Axicabtagene ciloleucel) and bispecific T cell engagers (such as Blinatumomab) developed based on this target have achieved breakthrough efficacy in hematologic malignancy treatment. Furthermore, CD19-targeted therapy has demonstrated potential in inducing B cell depletion and disease remission in autoimmune diseases such as systemic lupus erythematosus, though vigilance is required for adverse effects including cytokine release syndrome and neurotoxicity.