Patent ID: 8168185

Claim:
A method separating and purifying an anti CD-25 antibody from a fluid comprising at least a cation exchange chromatography purification step comprising: (a) binding fluid comprising anti CD-25 antibody to a cation exchange resin; (b) washing the cation exchange resin with a buffer at a pH about 1 unit below the isoelectric point of the anti CD-25 antibody, the buffer having a conductivity of about 2 to 6 mS/cm; and (c) eluting the anti CD-25 antibody with a buffer at a pH about 1 unit below the isoelectric point of the anti CD-25 antibody with an increasing salt gradient; wherein: said anti CD-25 antibody comprises a human heavy chain variable region comprising the amino acid sequence as set forth in SEQ ID NO: 1 and a human kappa light chain variable region comprising the amino acid sequence as set forth in SEQ ID NO: 2, or conservative sequence modifications thereof; or said anti CD-25 antibody comprises the following VH CDRs: (i) SEQ ID NO: 3 (VH CDR1), SEQ ID NO: 4 (VH CDR2) and SEQ ID NO: 5 (VH CDR3) and the following VL CDRs: SEQ ID NO: 6 (VL CDR1), SEQ ID NO: 7 (VL CDR2) and SEQ ID NO: 8 (VL CDR3): or (ii) conservative sequence modifications of any one of the sequences defined in (i).