Ilt3 Binding Molecules And Uses Therefor

Abstract

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 - 43 . (canceled) 
     
     
         44 . An isolated antibody that specifically binds ILT3, or an antigen-binding fragment of the antibody, comprising:
 a heavy chain variable region (VH) complementarity determining region 1 (VH CDR1) comprising the amino acid sequence shown in SEQ ID NO: 3;   a heavy chain variable region (VH) complementarity determining region 2 (VH CDR2) comprising the amino acid sequence shown in SEQ ID NO: 4;   a heavy chain variable region (VH) complementarity determining region 3 (VH CDR3) comprising the amino acid sequence shown in SEQ ID NO: 5; and   at least one framework region present in one of SEQ ID NOs: 48-63.   
     
     
         45 . The isolated antibody or antigen-binding fragment of  claim 44 , wherein the antibody or antigen-binding fragment is selected from the group consisting of a single chain antibody, an scFv fragment, a Fab fragment, a F(ab′) 2  fragment, a humanized antibody, and a chimeric antibody. 
     
     
         46 . The isolated antibody or antigen-binding fragment of  claim 44 , further comprising a human heavy chain constant region. 
     
     
         47 . The isolated antibody or antigen-binding fragment of  claim 46 , wherein the human heavy chain constant region comprises the amino acid sequence shown in one of SEQ ID NOs: 30 or 31. 
     
     
         48 . An isolated antibody that specifically binds ILT3, or an antigen-binding fragment of the antibody, comprising:
 a heavy chain variable region (VH) complementarity determining region 1 (VH CDR1) comprising the amino acid sequence shown in SEQ ID NO: 3;   a heavy chain variable region (VH) complementarity determining region 2 (VH CDR2) comprising the amino acid sequence shown in SEQ ID NO: 4; and   a heavy chain variable region (VH) complementarity determining region 3 (VH CDR3) comprising the amino acid sequence shown in SEQ ID NO: 5;   wherein framework regions of the VH are human VH framework regions, except that one or more human framework amino acid residues of the human VH framework regions are backmutated to corresponding murine amino acid residues present in SEQ ID NO: 1;   wherein the one or more human framework amino acid residues backmutated to the corresponding murine amino acid residues are 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.   
     
     
         49 . An isolated antibody that specifically binds ILT3, or an antigen-binding fragment of the antibody, comprising:
 a light chain variable region (VL) complementarity determining region 1 (VL CDR1) comprising the amino acid sequence shown in SEQ ID NO: 6;   a light chain variable region (VL) complementarity determining region 2 (VL CDR2) comprising the amino acid sequence shown in SEQ ID NO: 7;   a light chain variable region (VL) complementarity determining region 3 (VL CDR3) comprising the amino acid sequence shown in SEQ ID NO: 8; and   at least one framework region present in one of SEQ ID NOs: 36-47 or 64.   
     
     
         50 . The isolated antibody or antigen-binding fragment of  claim 49 , wherein the antibody or antigen-binding fragment is selected from the group consisting of a single chain antibody, an scFv fragment, a Fab fragment, a F(ab′) 2  fragment, a humanized antibody, and a chimeric antibody. 
     
     
         51 . The isolated antibody or antigen-binding fragment of  claim 49 , further comprising a human light chain constant region. 
     
     
         52 . The isolated antibody or antigen-binding fragment of  claim 51 , wherein the human light chain constant region comprises the amino acid sequence shown in SEQ ID NO: 32. 
     
     
         53 . An isolated antibody that specifically binds ILT3, or an antigen-binding fragment of the antibody, comprising:
 a light chain variable region (VL) complementarity determining region 1 (VL CDR1) comprising the amino acid sequence shown in SEQ ID NO: 6;   a light chain variable region (VL) complementarity determining region 2 (VL CDR2) comprising the amino acid sequence shown in SEQ ID NO: 7; and   a light chain variable region (VL) complementarity determining region 3 (VL CDR3) comprising the amino acid sequence shown in SEQ ID NO: 8,   wherein framework regions of the VL are human VL framework regions, except that one or more human framework amino acid residues of the human VL framework regions are backmutated to corresponding murine amino acid residues present in SEQ ID NO: 2;   wherein the one or more human framework amino acid residues backmutated to the corresponding murine amino acid residues are 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.   
     
     
         54 . An isolated antibody that specifically binds ILT3, or an antigen-binding fragment of the antibody, comprising:
 a heavy chain variable region (VH) complementarity determining region 1 (VH CDR1) comprising the amino acid sequence shown in SEQ ID NO: 3;   a heavy chain variable region (VH) complementarity determining region 2 (VH CDR2) comprising the amino acid sequence shown in SEQ ID NO: 4;   a heavy chain variable region (VH) complementarity determining region 3 (VH CDR3) comprising the amino acid sequence shown in SEQ ID NO: 5;   a light chain variable region (VL) complementarity determining region 1 (VL CDR1) comprising the amino acid sequence shown in SEQ ID NO: 6;   a light chain variable region (VL) complementarity determining region 2 (VL CDR2) comprising the amino acid sequence shown in SEQ ID NO: 7;   a light chain variable region (VL) complementarity determining region 3 (VL CDR3) comprising the amino acid sequence shown in SEQ ID NO: 8; and   at least one framework region present in one of SEQ ID NOs: 36-64.   
     
     
         55 . The isolated antibody or antigen-binding fragment of  claim 54 , wherein the antibody or antigen-binding fragment is selected from the group consisting of a single chain antibody, an scFv fragment, a Fab fragment, a F(ab′) 2  fragment, a humanized antibody, and a chimeric antibody. 
     
     
         56 . The isolated antibody or antigen-binding fragment of  claim 54 , further comprising a human heavy chain constant region. 
     
     
         57 . The isolated antibody or antigen-binding fragment of  claim 56 , wherein the human heavy chain constant region comprises the amino acid sequence shown in one of SEQ ID NOs: 30-31. 
     
     
         58 . The isolated antibody or antigen-binding fragment of  claim 54 , further comprising a human light chain constant region. 
     
     
         59 . The isolated antibody or antigen-binding fragment of  claim 58 , wherein the human light chain constant region comprises the amino acid sequence shown in SEQ ID NO: 32. 
     
     
         60 . An isolated antibody that specifically binds ILT3, or an antigen-binding fragment of the antibody, comprising:
 a heavy chain variable region (VH) complementarity determining region 1 (VH CDR1) comprising the amino acid sequence shown in SEQ ID NO: 3;   a heavy chain variable region (VH) complementarity determining region 2 (VH CDR2) comprising the amino acid sequence shown in SEQ ID NO: 4;   a heavy chain variable region (VH) complementarity determining region 3 (VH CDR3) comprising the amino acid sequence shown in SEQ ID NO: 5;   a light chain variable region (VL) complementarity determining region 1 (VL CDR1) comprising the amino acid sequence shown in SEQ ID NO: 6;   a light chain variable region (VL) complementarity determining region 2 (VL CDR2) comprising the amino acid sequence shown in SEQ ID NO: 7; and   a light chain variable region (VL) complementarity determining region 3 (VL CDR3) comprising the amino acid sequence shown in SEQ ID NO: 8;   wherein framework regions of the VH and VL are human VH and VL framework regions, except that one or more human framework amino acid residues of the human VH framework regions are backmutated to corresponding murine amino acid residues present in SEQ ID NO: 1;   wherein the one or more human framework amino acid residues backmutated to the corresponding murine amino acid residues are 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.   
     
     
         61 . An isolated antibody that specifically binds ILT3, or an antigen-binding fragment of the antibody, comprising:
 a heavy chain variable region (VH) complementarity determining region 1 (VH CDR1) comprising the amino acid sequence shown in SEQ ID NO: 3;   a heavy chain variable region (VH) complementarity determining region 2 (VH CDR2) comprising the amino acid sequence shown in SEQ ID NO: 4;   a heavy chain variable region (VH) complementarity determining region 3 (VH CDR3) comprising the amino acid sequence shown in SEQ ID NO: 5;   a light chain variable region (VL) complementarity determining region 1 (VL CDR1) comprising the amino acid sequence shown in SEQ ID NO: 6;   a light chain variable region (VL) complementarity determining region 2 (VL CDR2) comprising the amino acid sequence shown in SEQ ID NO: 7; and   a light chain variable region (VL) complementarity determining region 3 (VL CDR3) comprising the amino acid sequence shown in SEQ ID NO: 8;   wherein framework regions of the VH and VL are human VH and VL framework regions, except that one or more human framework amino acid residues of the human VL framework regions are backmutated to corresponding murine amino acid residues present in SEQ ID NO: 2;   wherein the one or more human framework amino acid residues backmutated to the corresponding murine amino acid residues are 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.   
     
     
         62 . An isolated antibody that specifically binds ILT3, or an antigen-binding fragment of the antibody, wherein the antibody or antigen-binding fragment competes for binding to ILT3 with the antibody or antigen-binding fragment of  claim 44 . 
     
     
         63 . An isolated antibody that specifically binds ILT3, or an antigen-binding fragment of the antibody, wherein the antibody or antigen-binding fragment competes for binding to ILT3 with the antibody or antigen-binding fragment of  claim 49 .