Fc receptor antibodies and methods of use thereof

1. An isolated anti-neonatal Fc receptor (FcRn) antibody comprising a light chain variable region (V L ) and a heavy chain variable region (V H ), wherein the antibody binds to human FcRn;

wherein the V L comprises:

(i) a V L CDR1 comprising the amino acid sequence of SEQ ID NO:14;

(ii) a V L CDR2 comprising the amino acid sequence of SEQ ID NO:15; and

(iii) a V L CDR3 comprising the amino acid sequence of SEQ ID NO:12 or SEQ ID NO:13; and

wherein the V H comprises:

(i) a V H CDR1 comprising the amino acid sequence of SEQ ID NO:22;

(ii) a V H CDR2 comprising the amino acid sequence of SEQ ID NO:23; and

(iii) a V H CDR3 comprising the amino acid sequence of SEQ ID NO:24.

2. The isolated antibody of claim 1 , wherein the V L of the isolated antibody comprises the amino acid sequence of SEQ ID NO: 10 or SEQ ID NO: 11.

3. The isolated antibody of claim 1 , wherein the V H of the isolated antibody comprises the amino acid sequence of SEQ ID NO: 9.

4. The isolated antibody of claim 1 , wherein the isolated antibody is a human or humanized antibody or is non-immunogenic in a human.

5. The isolated antibody of claim 4 , wherein the isolated antibody comprises a human antibody framework region.

6. The isolated antibody of claim 1 , wherein the isolated antibody is a murine antibody.

7. The isolated antibody of claim 1 , wherein the isolated antibody is chimeric.

8. The isolated antibody of claim 1 , wherein the isolated antibody is a full-length antibody.

9. The isolated antibody of claim 1 , wherein the isolated antibody is selected from the group consisting of Fab, F(ab)′2, Fv, and scFv.

10. A pharmaceutical composition comprising the isolated antibody of claim 1 and a pharmaceutically acceptable carrier.

11. A method of detecting an FcRn in a sample or in a subject, the method comprising:

contacting the sample with the isolated antibody of claim 1 , and

detecting an interaction between the isolated antibody and the FcRn if present.

12. A method of modulating the half-life or level of a circulating IgG in a subject, the method comprising administering to the subject the isolated antibody of claim 1 in an amount effective to modulate the half-life or level of a circulating IgG in the subject.

13. The method of claim 12 , wherein the subject has an autoimmune disease or an inflammatory disorder.

14. The method of claim 12 , wherein the subject contains an unwanted IgG in the bloodstream.

15. The method of claim 14 , wherein the unwanted IgG is an anti-human leukocyte antigen (HLA) IgG antibody.

16. The method of claim 15 , wherein the subject has received an organ transplant.