Patent ID: 7820166

Claim:
A polypeptide construct comprising the CDR-1, CDR-2, CDR-3 regions of V L , as well as the CDR-1, CDR-2, CDR-3 regions of V H , wherein the CDR-3 of V H is selected from the group consisting of: Y Y N D Q Y (M13, SEQ ID NO: 8), Y S D V Y Y (M58, SEQ ID NO: 12), and Y N D E H Y (M69, SEQ ID NO: 14), and wherein said polypeptide construct has a low binding affinity for CD3 and is highly efficacious in activating a T-cell; and wherein the V L polypeptide chain comprises the CDR-1, CDR-2 and CDR-3 regions of the murine OKT3 anti-CD3 antibody V L polypeptide chain and the V H polypeptide chain comprises the CDR-1 and CDR-2 regions of the murine OKT3 anti-CD3 antibody V H polypeptide chain.