Patent ID: 8765385

Claim:
A method for detecting in a sample the presence of a neutralizing anti-ActRIIB antibody, the method comprising: (i) forming a mixture comprising the sample, an ActRIIB polypeptide and a control antibody that is a known neutralizing, monoclonal anti-ActRIIB antibody, wherein the anti-ActRIIB antibody comprises: a) a light chain comprising: i) a CDR1 comprising the amino acid sequence of SEQ ID NO:40; ii) a CDR2 comprising the amino acid sequence of SEQ ID NO:41; and iii) a CDR3 comprising the amino acid sequence of SEQ ID NO:42; and b) a heavy chain comprising: i) a CDR1 comprising the amino acid sequence of SEQ ID NO:37; ii) a CDR2 comprising the amino acid sequence of SEQ ID NO:38; and iii) a CDR3 comprising the amino acid sequence of SEQ ID NO:39; and (ii) measuring the amount of control antibody that is bound to the ActRIIB polypeptide, wherein the ActRIIB polypeptide is a polypeptide comprising a ligand-binding domain of ActRIIB, and wherein a decrease in the amount of control antibody bound to the ActRIIB polypeptide relative to a standard indicates that the sample contains a neutralizing anti-ActRIIB antibody.