Recombinant Anti-CD19 x Anti-CD3 Bispecific Antibody (IgG(L)-scFv) is formed by an IgG and two scFv moieties. The scFv fragments from an anti-CD19 antibody are fused to the C terminus of an anti-CD3 IgG light (L) chains, or vice versa. It is a type of appended IgGs, which is bispecific and tetravalent (2+2 antigen-binding valency). This BsAb can retarget T cells to tumor cells. It is designed for the research of B cell lymphoma; Follicular lymphoma; Leukemia therapy.