Protein purification method

Abstract

A method is provided for purifying physiologically active proteins, especially antibodies, in order to remove impurities such as DNA contaminants and viruses with minimal loss of physiologically active proteins. The physiologically active protein is introduced into an aqueous solution of low conductivity at a pH of below the isoelectric point of the physiologically active protein to precipitate impurities as particles. The particles are removed, leaving a purified physiologically active protein.

1 - 6 . (canceled) 
     
     
         7 . A method for manufacturing an antibody formulation, which comprises the steps:
 1) applying a composition comprising the antibody and viruses to a protein-A or protein-G affinity column, which binds the antibody,   2) eluting the bound antibody with an aqueous solution of pH of 2.0 to 3.9 and an ionic concentration of 50 mM or less,   3) adjusting the pH of the eluate of step 2) to a pH of from 4.0 to 7.5 by adding a buffer,   4) removing particles comprising the viruses from the eluate of step 3),   thereby obtaining the antibody formulation.   
     
     
         8 . The method according to  claim 7 , wherein the antibody is humanized IL-6 receptor antibody. 
     
     
         9 . The method according to  claim 8 , wherein the antibody is hPM-1 antibody.