Recombinant Anti-CD28 x Anti-CD3 Bispecific Antibody (IgG(L)-scFv) is formed by an IgG and two scFv moieties. The scFv fragments from an anti-CD28 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 improve T-cell activation. It is designed for the research of Tumors therapy.