Used in research and development of immunotherapies targeting B-cell malignancies such as leukemia and lymphoma. Binds specifically to the CD19 antigen expressed on B cells, enabling the study of B-cell signaling, depletion strategies, and chimeric antigen receptor (CAR) design. Commonly used as a benchmark in flow cytometry, immunohistochemistry, and in vivo models to evaluate new anti-CD19 therapeutics. Supports the validation of drug candidates and diagnostic tools in oncology and autoimmune disease research.