Methods of purifying antibodies
The invention provides methods of purifying antibodies using various antibody-specific purification media to rapidly and efficiently separate mixtures of antibodies, antibody fragments and/or antibody components to isolate a desired antibody product from the mixture. The invention relates to the purification of bispecific monoclonal antibodies carrying a different specificity for each binding site of the immunoglobulin molecule, e.g., antibodies composed of a single heavy chain and two different light chains, one containing a Kappa constant domain and the other a Lambda constant domain, including antibodies of different specificities that share a common heavy chain. The invention also provides the methods of efficiently purifying intact antibodies by separating the intact antibody from non-intact antibodies including free light chains.
1. A method of purifying a bispecific antibody consisting of two copies of a single heavy chain polypeptide and a first light chain comprising a kappa constant region and a second light chain comprising a lambda constant region (κλ-bodies), the method consisting of the steps:
(a) providing a mixed antibody composition comprising κλ-bodies; one or more monospecific monoclonal antibodies having two lambda light chains (λ-MAb); and one or more monospecific monoclonal antibodies having two kappa light chains (κ-MAb);
(b) providing a separation means that has specific affinity for a kappa light chain constant region or a lambda light chain constant region;
(c) contacting the separation means with the mixed antibody composition under conditions that allow for the mixed antibody composition to specifically bind the separation means;
(d) washing the separation means to elute impurities;
(e) eluting the κλ-bodies under conditions that allow for preferential detachment of the κλ-bodies thereby purifying the κλ-bodies.
2. The method of claim 1 , wherein the separation means having specific affinity for kappa light chain constant region is
a resin, a membrane, a magnetic bead, a particle or a monolith coupled to a ligand having specific affinity for the kappa light chain constant region; and the separation means having specific affinity for lambda light chain constant region is
a resin, a membrane, a magnetic bead, a particle or a monolith coupled to a ligand having specific affinity for the lambda light chain constant region.
3. The method of claim 1 , wherein the elution conditions comprise a step variation in the pH level.
4. The method of claim 1 , wherein the elution conditions comprise a variation of the concentration of an amino acid in the composition.
5. The method of claim 4 , wherein the amino acid is arginine, histidine, proline, phenylalanine, tyrosine, tryptophan and/or glycine.
6. A single step affinity chromatography method of purifying a bispecific antibody consisting of two copies of a single heavy chain polypeptide and a first light chain comprising a kappa constant region and a second light chain comprising a lambda constant region (κλ-bodies), the method consisting of:
(a) providing a mixed antibody composition comprising κλ-bodies; one or more monospecific monoclonal antibodies having two lambda light chains (λ-MAb); and one or more monospecific monoclonal antibodies having two kappa light chains (κ-MAb);
(b) providing a separation means, wherein the separation means is an anti-kappa light chain antibody, or an anti-lambda light chain antibody coupled to a solid support;
(c) contacting the separation means with the mixed antibody composition under conditions that allow for the mixed antibody composition to specifically bind the separation means;
(d) washing the separation means to elute impurities with a wash solution having a pH of about 7.0 or higher; and
(e) eluting specifically the κλ-bodies with an elution solution having a pH of about 3.0, thereby purifying the κλ-bodies.
7. The method of claim 6 , wherein the solid support is a resin, a membrane, a magnetic bead, a particle or a monolith.
8. The method of claim 6 , wherein the solid support is a highly cross-linked agarose.