To provide a CD3
antibody that is capable of binding to
primate CD3, has a suitable CD3 binding capacity, and has a stable single-chain scFv structure.SOLUTION: Disclosed are a CD3-targeting
antibody, a
bispecific antibody and the use thereof. The CD3-targeting
antibody comprises a light chain variable region (VL) and a
heavy chain variable region (VH). The VL has the
amino acid sequence as shown in SEQ ID NO: 56 or a
mutation thereof. The VH has mutations on the
amino acid sequence as shown in SEQ ID NO: 42, and the mutations occur at one or more of the sites of
amino acid residues selected from positions 30, 73, 76, 78, 93 and 94. The
bispecific antibody comprises a first
protein domain and a second
protein domain, wherein the first
protein domain comprises the CD3-targeting antibody as described above. The CD3-targeting antibody reduces the
toxicity caused by
cytokine release syndrome, and the
bispecific antibody prepared therefrom is stable and has the ability to bind to T cells, and also reduces the difficulty of producing.SELECTED DRAWING: Figure 11