Anti-ilt7 antibody

Abstract

An antibody binding to IPC was obtained by using an animal cell in which a cell membrane protein associatable with ILT7 was co-expressed as an immunogen. The antibody of the invention has a high specificity which allows immunological distinction between other ILT family molecules and ILT7. The anti-ILT7 antibody of the invention bound to IPC and inhibited the activity thereof. With the anti-ILT7 antibody of the invention, the IPC activity can be inhibited and an interferon-related disease can be treated or prevented. ILT7 expression is maintained even in IPC in the presence of IFNα. Therefore, an inhibitory action of IPC activity by the anti-ILT7 antibody can be expected even in an autoimmune disease patient with an increased production of IFNα.

1 . A monoclonal antibody which binds to an extracellular domain of human ILT7 or a fragment comprising its antigen binding region. 
     
     
         2 . The monoclonal antibody or the fragment comprising its antigen binding region according to  claim 1 , wherein the monoclonal antibody binds to a human interferon producing cell. 
     
     
         3 . (canceled) 
     
     
         4 . The monoclonal antibody or the fragment comprising its antigen binding region according to  claim 1 , wherein the monoclonal antibody comprises amino acid sequences according to any of the following i) to iii) as CDR1, CDR2, and CDR3 in the heavy chain variable region and the light chain variable region:
 i) CDR1 of a heavy chain variable region: SDYAWN (SEQ ID NO: 58);   CDR2 of a heavy chain variable region: YISYSGSTSYNPSLKSR (SEQ ID NO: 59); and   CDR3 of a heavy chain variable region: SPPYYAMDY (SEQ ID NO: 60);   CDR1 of light chain variable region: KASQDVGTAVA (SEQ ID NO: 61);   CDR2 of a light chain variable region: WASTRHT (SEQ ID NO: 62); and   CDR3 of a light chain variable region: QQYSSYPLT (SEQ ID NO: 63);   ii) CDR1 of a heavy chain variable region: SYWIH (SEQ ID NO: 64);   CDR2 of a heavy chain variable region: RIYPGTGSTYYNEKFKG (SEQ ID NO: 65); and   CDR3 of a heavy chain variable region: YPTYDWYFDV (SEQ ID NO: 66);   CDR1 of a light chain variable region: RASQSISNYLH (SEQ ID NO: 67);   CDR2 of a light chain variable region: YASQSIS (SEQ ID NO: 68);   CDR3 of a light chain variable region: QQSNSWPLT (SEQ ID NO: 69);   iii) CDR1 of a heavy chain variable region: SDYAWN (SEQ ID NO: 70);   CDR2 of a heavy chain variable region: YISYSGSTSYNPSLKSR (SEQ ID NO: 71);   CDR3 of a heavy chain variable region: ALPLPWFAY (SEQ ID NO: 72);   CDR1 of a light chain variable region: KASQDVGTAVA (SEQ ID NO: 73);   CDR2 of a light chain variable region: WASTRHT (SEQ ID NO: 74); and   CDR3 of a light chain variable region: QQYSSYPYT (SEQ ID NO: 75).   
     
     
         5 . The monoclonal antibody or the fragment comprising its antigen binding region according to  claim 1 , wherein the monoclonal antibody comprises a mature sequence of an amino acid sequence selected from any of the following combinations (a) to (c) as the heavy chain variable region and the light chain variable region;
 a) a heavy chain variable region of SEQ ID NO: 39 and a light chain variable region of SEQ ID NO: 41;   b) a heavy chain variable region of SEQ ID NO: 43 and a light chain variable region of SEQ ID NO: 45; and   c) a heavy chain variable region of SEQ ID NO: 47 and a light chain variable region of SEQ ID NO: 49.   
     
     
         6 . A polynucleotide encoding the monoclonal antibody or the fragment comprising its antigen binding region according to  claim 4 . 
     
     
         7 . A vector comprising a polynucleotide encoding the monoclonal antibody or the fragment comprising its antigen binding region according to  claim 4 . 
     
     
         8 . A transformed cell retaining the vector according to  claim 7  in an expressible manner. 
     
     
         9 . A method for producing the monoclonal antibody or the fragment comprising its antigen binding region according to  claim 4 , comprising the steps of: culturing the transformed cell according to  claim 8 ; and recovering the monoclonal antibody or the fragment comprising its antigen binding region from the culture. 
     
     
         10 . A hybridoma which produces the monoclonal antibody according to  claim 1 . 
     
     
         11 - 12 . (canceled) 
     
     
         13 . A method for producing a cell which produces a monoclonal antibody which binds to an extracellular domain of human ILT7, comprising the following steps of:
 (1) administering to an immune animal a cell which expresses a exogenous protein comprising an extracellular domain of human ILT7 and a exogenous molecule which associates with human ILT7; and   (2) selecting an antibody producing cell which produces an antibody which binds to human ILT7 from the antibody producing cell of the immune animal.   
     
     
         14 . The method according to  claim 13 , wherein the molecule which associates with human ILT7 is a cell membrane protein. 
     
     
         15 . The method according to  claim 14 , wherein the cell membrane protein is Fc receptor γ chain. 
     
     
         16 . The method according to  claim 15 , wherein the cell expressing human ILT7 and the molecule which associates with human ILT7 is a cell retaining the following (a) and (b) in an expressible manner:
 (a) an exogenous polynucleotide encoding an amino acid sequence comprising an extracellular domain of human ILT7; and   (b) an Fc receptor γ chain A polynucleotide encoding an exogenous polynucleotide, and a foreign polynucleotide.   
     
     
         17 . The method according to  claim 16 , wherein the cell is an animal cell. 
     
     
         18 . The method according to  claim 17 , wherein the cell is a human-derived cell. 
     
     
         19 . The method according to  claim 18 , wherein the human-derived cell is a 293T cell. 
     
     
         20 . The method according to  claim 13 , additionally comprising a step of cloning the antibody producing cell obtained by the method according to  claim 13 . 
     
     
         21 - 26 . (canceled) 
     
     
         27 . A method for inhibiting the activity of an interferon producing cell, comprising a step of contacting any of the following components with an interferon producing cell:
 (a) a monoclonal antibody which binds to human ILT7 and inhibits the activity of an interferon producing cell or a fragment comprising its antigen binding region; and   (b) an immunoglobulin into which a complementarity-determining region of the monoclonal antibody described in (a) is introduced or a fragment comprising its antigen binding region.   
     
     
         28 . (canceled) 
     
     
         29 . The method according to  claim 27 , wherein the activity of the interferon producing cell is due to either the interferon producing activity or the survival of the interferon producing cell, or both of them. 
     
     
         30 - 31 . (canceled)