ILT3 binding molecules and uses therefor
View Patent ↗The present invention provides binding molecules that specifically bind to ILT3, e.g., human ILT3 (hILT3), on antigen presenting cells, such as for example, monocytes, macrophages and dendritic cells (DC), e.g., monocyte-derived dendritic cells (MDDC). The binding molecules of the invention are characterized by binding to hILT3 with high affinity and downmodulating immune responses in vitro, e.g., downmodulating alloimmune responses; the production of inflammatory cytokines by dendritic cells, e.g., monocyte-derived dendritic cells (MDDC); the upregulation of costimulatory molecules by DC, e.g., MDDC; and/or calcium flux in monocytes. In addition, the binding molecules upregulate the expression of inhibitory receptors on dendritic cells, e.g., immature dendritic cells. Surprisingly, these same binding molecules which downmodulate immune responses in vitro, are immunostimulatory in vivo. Various aspects of the invention relate to binding molecules, and pharmaceutical compositions thereof. Methods of using the binding molecules of the invention to detect human ILT3 or to modulate human ILT3 activity, either in vitro or in vivo, are also encompassed by the invention.
1. An isolated antibody that specifically binds ILT3, or an antigen binding fragment of the antibody, selected from the group consisting of:
a) an antibody or antigen binding fragment comprising the amino acid sequence of SEQ ID NO: 28, except that one or more human framework amino acid residues of the antibody or antigen binding fragment are backmutated to one or more corresponding murine framework amino acid residues of SEQ ID No. 2,
b) an antibody or antigen binding fragment comprising the amino acid sequence of SEQ ID NO: 29, except that one or more human framework amino acid residues of the antibody or antigen binding fragment are backmutated to one or more corresponding murine framework amino acid residues of SEQ ID No. 1, and
c) an antibody comprising the amino acid sequence of SEQ ID NO: 33 and further comprising the amino acid sequence of SEQ ID NO: 34, except that one or more human framework amino acid residues of the antibody or antigen binding fragment are backmutated to one or more corresponding murine framework amino acid residues of SEQ ID Nos. 1 or 2.
2. An isolated antibody that specifically binds ILT3 or an antigen binding fragment of the antibody, the antibody or antigen binding fragment comprising the amino acid sequence of SEQ ID NO: 28.
3. An isolated antibody that specifically binds ILT3 or an antigen binding fragment of the antibody, the antibody or antigen binding fragment comprising the amino acid sequence of SEQ ID NO: 29.
4. An isolated antibody that specifically binds ILT3 or an antigen binding fragment of the antibody, the antibody or antigen binding fragment comprising a light chain variable region comprising the amino acid sequence of SEQ ID NO :33 and further comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 34.
5. The isolated antibody or antigen binding fragment thereof, of any one of claims 2 , 3 and 4 , wherein the isolated antibody or antigen binding fragment downmodulates immune cell activation in vitro.
6. The isolated antibody or antigen binding fragment thereof, of any one of claims 2 , 3 and 4 , wherein the isolated antibody or antigen binding fragment upmodulates immune response in vivo.
7. The isolated antibody or antigen binding fragment thereof, of any one of claims 2 , 3 and 4 , wherein the isolated antibody or antigen binding fragment binds to human ILT3 on dendritic cells.
8. The isolated antibody or antigen binding fragment thereof, of any one of claims 2 , 3 and 4 , wherein the isolated antibody or antigen binding fragment binds to human ILT3 on monocytes.
9. The isolated antibody or antigen binding fragment thereof, of any one of claims 2 , 3 and 4 , wherein the isolated antibody or antigen binding fragment downmodulates the production of inflammatory cytokines by dendritic cells in vitro.
10. The isolated antibody or antigen binding fragment thereof, of any one of claims 2 , 3 and 4 , wherein the isolated antibody or antigen binding fragment downmodulates the upregulation of costimulatory molecules on dendritic cells in vitro.
11. The isolated antibody or antigen binding fragment thereof, of any one of claims 2 , 3 and 4 , wherein the isolated antibody or antigen binding fragment upmodulates the expression of inhibitory receptors on dendritic cells in vitro.
12. A composition comprising the isolated antibody or antigen binding fragment of any one of claims 2 , 3 and 4 and a pharmaceutically acceptable carrier.
13. The composition of claim 12 , further comprising at least one additional therapeutic agent which upmodulates an immune response in a subject.
14. An isolated antibody that specifically binds ILT3 or an antigen binding fragment of the antibody, the antibody or antigen binding fragment comprising a light chain variable region comprising the amino acid sequence of SEQ ID NO :28 and further comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 29.
15. The isolated antibody or antigen binding fragment of any one of claims 2 , 3 , 4 , and 14 comprising a heavy chain constant region.
16. The isolated antibody or antigen binding fragment of claim 15 , wherein the heavy chain constant region comprises the amino acid sequence of SEQ ID NO: 30.
17. The isolated antibody or antigen binding fragment of claim 15 , wherein the heavy chain constant region comprises the amino acid sequence of SEQ ID NO: 31.
18. The isolated antibody or antigen binding fragment of any one of claims 2 , 3 , 4 and 14 comprising a light chain constant region.
19. The isolated antibody or antigen binding fragment of claim 18 , wherein the light chain constant region comprises the amino acid sequence of SEQ ID NO: 32.
20. An isolated antibody that specifically binds ILT3 or an antigen binding fragment of the antibody, the antibody or antigen binding fragment comprising the amino acid sequence of SEQ ID NO: 33.
21. An isolated antibody that specifically binds ILT3 or an antigen binding fragment of the antibody, the antibody or antigen binding fragment comprising the amino acid sequence of SEQ ID NO: 34.
22. An isolated antibody that specifically binds ILT3 or an antigen binding fragment of the antibody, the antibody or antigen binding fragment comprising the amino acid sequence of SEQ ID NO: 35.
23. An isolated antibody that specifically binds ILT3 or an antigen binding fragment of the antibody, the antibody or antigen binding fragment comprising a light chain variable region comprising the amino acid sequence of SEQ ID NO :33 and further comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 35.
24. The isolated antibody or antigen binding fragment of claim 1 , wherein the one or more human framework amino acid residues backmutated to the corresponding murine amino acid residue is selected from the group consisting of amino acid residue number 3, 4, 9, 10, 13, 14, 15, 18, 20, 21, 22, 41, 42, 43, 45, 46, 49, 58, 70, 76, 78, 79, 80, 84, 85, 86, 87, and 100 of SEQ ID NO: 28.
25. The isolated antibody or antigen binding fragment thereof, of any claim 1 , wherein the one or more human framework amino acid residues backmutated to the corresponding murine amino acid residue is selected from the group consisting of amino acid residue number 3,10,19, 40, 42, 44, 49, 76, 78, 84, 88, 93, and 97 of SEQ ID NO: 29.
26. The isolated antibody or antigen binding fragment of any one of claims 2 3 4 , and 14 , which is an antigen binding fragment selected from the group consisting of a Fab fragment, a F(ab′)2 fragment and a scFv fragment.
27. The isolated antibody or antigen binding fragment of claim 1 , wherein amino acid residue number 100 of SEQ ID NO: 28 is backmutated to a corresponding murine framework amino acid residue of SEQ ID No. 2.
28. The isolated antibody or antigen binding fragment of claim 27 , wherein amino acid residue number 100 of SEQ ID NO: 28 is backmutated from a glutamine to an alanine.