Method of depleting target antigen-specific antibody from a patient by administering a fusion protein (seldeg) for selectively depleting antigen-specific antibodies

A pharmaceutical composition comprising a Seldeg which selectively depletes at least 50% of target antigen-specific antibodies from a circulation or a target tissue when administered to a subject, wherein the Seldeg comprises:

• (a) a targeting component having a protein or a protein fragment or a ligand configured to specifically bind to an internalizing cell surface receptor or an internalizing cell surface molecule;
• and
• (b) an antigen component having one molecule of an antigen, an antigen fragment or an antigen mimetic configured to specifically bind a target antigen-specific antibody or a variant thereof;
• wherein the targeting component is fused directly or indirectly to the antigen component.