A recombinant, single-chain, anti-CD19/anti-CD3 bispecific monoclonal antibody with potential immunostimulating and antineoplastic activities. Blinatumomab possesses two antigen-recognition sites, one for the CD3 complex, a group of T cell surface glycoproteins that complex with the T cell receptor (TCR), and one for CD19, a tumor-associated antigen (TAA) overexpressed on the surface of B cells. This bispecific monoclonal antibody brings CD19-expressing tumor B-cells and cytotoxic T lymphocytes (CTLs) and helper T lymphocytes (HTLs) together, which may result in the CTL- and HTL-mediated cell death of CD19-expressing B-lymphocytes.