Bispecific anti-human CD20/human transferrin receptor antibodies and methods of use

1. A bispecific antibody comprising

a) one antibody comprising two pairs each of an antibody light chain and an antibody heavy chain, wherein the binding sites formed by each of the pairs of the heavy chain and the light chain specifically bind to a first antigen, and

b) one additional Fab fragment, wherein the additional Fab fragment is fused to the C-terminus of one of the heavy chains of the antibody, wherein the binding site of the additional Fab fragment specifically binds to a second antigen,

wherein the additional Fab fragment specifically binding to the second antigen comprises a domain crossover such that the constant light chain domain (CL) and the constant heavy chain domain 1 (CH1) are replaced by each other,

wherein the first antigen is human CD20 protein and the second antigen is human transferrin receptor, and

wherein the bispecific antibody comprises a light chain comprising the amino acid sequence of SEQ ID NO: 1, a heavy chain comprising the amino acid sequence of SEQ ID NO: 2, a Fab fragment comprising a light chain comprising the amino acid sequence of SEQ ID NO: 3, and a heavy chain comprising the amino acid sequence of SEQ ID NO: 4.

2. The antibody of claim 1 , wherein the antibody is monoclonal.

3. A pharmaceutical formulation comprising the antibody of claim 1 and a pharmaceutically acceptable carrier.

4. A method of treating an individual having multiple sclerosis comprising administering to the individual an effective amount of the antibody of claim 1 .

5. A method of depleting brain sequestered B-cells expressing CD20 in an individual comprising administering to the individual an effective amount of the antibody of claim 1 to deplete brain sequestered B-cells expressing CD20.