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 - 31 . (canceled) 
     
     
         32 . A monoclonal antibody which binds to human ILT7, binds to none of human ILT1, human ILT2 and human ILT3, and suppresses interferon-α (IFNα) production from ILT7-expressing cells, or a fragment comprising its antigen binding region. 
     
     
         33 . The monoclonal antibody according to claim  1 , wherein the ILT7 expressing cell is an interferon producing cell (IPC). 
     
     
         34 . The monoclonal antibody according to claim  1  or  2 , wherein the cell is CD123 positive or BDCA-2 positive. 
     
     
         35 . The monoclonal antibody according to any one of claims  1  to  3 , wherein the cell is CD3 negative, CD14 negative, CD16 negative, CD19 negative, CD20 negative, and CD56 negative. 
     
     
         36 . The monoclonal antibody according to any one of claims  1  to  4 , wherein the monoclonal antibody is produced by a method comprising the following steps of:
 (1) administering to a non-human animal 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 exogenous polynucleotide encoding Fc receptor γ-chain (FcRγ); 
 
 (2) producing and selecting an antibody producing cell which produces an antibody which binds to human ILT7 from the antibody producing cell of the non-human animal; and 
 (3) culturing the cell so selected and recovering a monoclonal antibody from the culture. 
 
     
     
         37 . The monoclonal antibody according to claim  5 , wherein the cell is an animal cell; and optionally wherein the cell is a human-derived cell; and further optionally wherein the human-derived cell is a 293T cell. 
     
     
         38 . The monoclonal antibody according to any one of claims  1  to  4 , wherein the fragment comprising its antigen binding region is Fab, F(ab′)2, single chain Fv, or diabody. 
     
     
         39 . A method for detecting an interferon producing cell, comprising the steps of: contacting the monoclonal antibody of any one of claims  1  to  7  with a test cell; and detecting the monoclonal antibody or the fragment comprising its antigen binding region which is bound to the cell. 
     
     
         40 . An interferon α (IFNα)-suppressing agent comprising the monoclonal antibody according to any one of claims  1  to  7  as an active ingredient.