Ligand (ACT-4-L) to a receptor on the surface of activated CD4+ T-cells

Abstract

The invention provides ligands and fragments thereof to a receptor on the surface of activated CD4 + T-cells. An exemplary ligand is designated ACT-4-L-h-1. Preferred fragments include purified extracellular domains of ligands. The invention also provides humanized and human antibodies to the ligand. The invention further provides methods of using the ligand and the antibodies in treatment of diseases and conditions of the immune system. The invention also provides methods of monitoring activated CD4 + T-cells using the ligands or fragments thereof.

1 . A purified ACT-4-L ligand polypeptide having a segment between 5 and 160 contiguous amino acids from an amino acid sequence shown in  FIG. 10 .  
     
     
         2 . The polypeptide of  claim 1  that exhibits at least eighty percent sequence identity to the amino acid sequence of  FIG. 10 .  
     
     
         3 . The polypeptide of  claim 2  having an antigenic determinant common to a protein with the amino acid sequence shown in  FIG. 10 .  
     
     
         4 . The polypeptide of  claim 3  comprising an intracellular domain, a transmembrane domain, or an extracellular domain.  
     
     
         5 . The polypeptide of  claim 1  that comprises an extracellular domain of an ACT-4-L ligand.  
     
     
         6 . The polypeptide of  claim 1  that is glycosylated.  
     
     
         7 . The polypeptide of  claim 6  further comprising a linked second polypeptide.  
     
     
         8 . The polypeptide of  claim 7 , wherein the second polypeptide is an immunoglobulin constant domain.  
     
     
         9 . A purified extracellular domain of an ACT-4-L ligand comprising at least five contiguous amino acids from the full-length ACT-4-L-h-1 extracellular domain.  
     
     
         10 . The extracellular domain of  claim 9  that is full-length.  
     
     
         11 . The extracellular domain of  claim 9  that is in soluble form.  
     
     
         12 . The extracellular domain of  claim 11  that specifically binds to the ACT-4-L-h-1 ligand.  
     
     
         13 . The extracellular domain of  claim 11  that specifically binds to the ACT-4-h-1 receptor.  
     
     
         14 . The extracellular domain of  claim 13  consisting essentially of a domain that specifically binds to the ACT-4-h-1 receptor.  
     
     
         15 . The extracellular domain of  claim 9  that is labelled.  
     
     
         16 . The extracellular domain of  claim 9  that inhibits in vitro activation of CD4 +  T cells expressing the ACT-4-h-1 receptor on their surface.  
     
     
         17 . The extracellular domain of  claim 9  that stimulates in vitro activation of CD4 +  T cells expressing the ACT-4-h-1 receptor on their surface.  
     
     
         18 . The extracellular domain of  claim 9  that competes with an antibody designated L106 for specific binding to the ACT-4-h-1 receptor.  
     
     
         19 . The extracellular domain of  claim 9  that competes with the ACT-4-L-h-1 ligand for binding to an antibody.  
     
     
         20 . The extracellular domain of  claim 9  further comprising a linked second polypeptide.  
     
     
         21 . The extracellular domain of  claim 20 , wherein the second polypeptide is a constant region of an immunoglobulin heavy chain.  
     
     
         22 . An ACT-4 receptor polypeptide consisting essentially of a domain that specifically binds to the ACT-4-L-h-1 ligand.  
     
     
         23 . A humanized monoclonal antibody comprising a humanized heavy chain and a humanized light chain: 
 (1) the humanized light chain comprising three complementarity determining regions (CDR1, CDR2 and CDR3) having amino acid sequences from the corresponding complementarity determining regions of a light chain of a nonhuman antibody that specifically binds to an extracellular domain of the ACT-4-L-h-1 ligand, and having a variable region framework sequence substantially identical to a human light chain variable region framework sequence; and    (2) the humanized heavy chain comprising three complementarity determining regions (CDR1, CDR2 and CDR3) having amino acid sequences from the corresponding complementarity determining regions a heavy chain of the nonhuman antibody, and having a variable region framework sequence substantially identical to a human heavy chain variable region framework sequence;    wherein the humanized antibody specifically binds to the extracellular domain of the ACT-4-L-h-1 ligand with a binding affinity having a lower limit of 10 7  M −1  and an upper limit that is within five-fold of the binding affinity of the nonhuman antibody.    
     
     
         24 . The humanized monoclonal antibody of  claim 23 , wherein the ACT-4-L-h-1 ligand is on the surface of a B cell and the binding of the antibody to the ligand inhibits activation of the B cell.  
     
     
         25 . The humanized monoclonal antibody of  claim 23 , wherein the ACT-4-L-h-1 ligand is on the surface of a B cell and the binding of the antibody to the ligand stimulates activation of the B-cell.  
     
     
         26 . The humanized monoclonal antibody of  claim 23 , wherein the ACT-4-L-h-1 ligand is on the surface of a B cell and the binding of the antibody to the ligand inhibits the capacity of the B-cells to activate CD4 +  T-cells.  
     
     
         27 . A human monoclonal antibody that specifically binds to an extracellular domain of the ACT-4-L-h-1 ligand.  
     
     
         28 . A purified nucleic acid segment encoding an ACT-4-L ligand polypeptide of  claim 1 .  
     
     
         29 . The purified nucleic acid segment of  claim 28  further comprising at least 25 contiguous nucleotides between nucleotides 1 and 112 of the 5′-untranslated region of the sequence shown in  FIG. 10 .  
     
     
         30 . A purified nucleic acid segment having between 15 and 500 contiguous nucleotides from the sequence shown in  FIG. 10 .  
     
     
         31 . An isolated population of cells substantially enriched in B-cells expressing an ACT-4-L ligand on their surface.  
     
     
         32 . An isolated stable cell line expressing an ACT-4-L ligand on its surface.  
     
     
         33 . A pharmaceutical composition comprising a pharmaceutically active carrier and an agent that specifically binds to an extracellular domain of the ACT-4-L-h-1 ligand.  
     
     
         34 . A method of suppressing an immune response in a patient having an immune disease or condition, the method comprising administering an effective amount of a pharmaceutical composition comprising a pharmaceutically active carrier and an agent that specifically binds to the ACT-4-L-h-1 ligand.  
     
     
         35 . The method of  claim 34 , wherein the agent competes with the ACT-4-h-1 receptor for specific binding to the ACT-4-L-h-1 ligand.  
     
     
         36 . The method of  claim 35 , wherein the agent is a monoclonal antibody.  
     
     
         37 . The method of  claim 36 , wherein the monoclonal antibody is humanized.  
     
     
         38 . The method of  claim 36 , wherein the monoclonal antibody is human.  
     
     
         39 . The method of  claim 35 , wherein the agent is an ACT-4-L ligand polypeptide.  
     
     
         40 . The method of  claim 35 , wherein the agent is a second ACT-4 receptor polypeptide consisting essentially of a domain that binds to the ACT-4-L-h-1 ligand.  
     
     
         41 . The method of  claim 35 , wherein the administering step is performed ex vivo.  
     
     
         42 . A method of suppressing an immune response in a patient having an immune disease or condition, the method comprising administering an effective amount of a pharmaceutical composition comprising a pharmaceutically active carrier and an agent that competes with the ACT-4-L ligand for specific binding to the ACT-4-h-1 receptor.  
     
     
         43 . The method of  claim 42 , wherein the agent is a monoclonal antibody.  
     
     
         44 . The method of  claim 42 , wherein the agent is a second ACT-4-L ligand polypeptide.  
     
     
         45 . The method of  claim 42 , wherein the agent is an ACT-4 receptor polypeptide consisting essentially of a domain that binds to the ACT-4-h-1 receptor.  
     
     
         46 . A method of screening for immunosuppressive agents, the method comprising: 
 contacting an ACT-4-L-h-1 ligand polypeptide with a potential immunosuppressive agent; and    detecting specific binding between the ACT-4-L-h-1 ligand polypeptide and the agent, the specific binding indicative of immunosuppressive activity.    
     
     
         47 . The method of  claim 46 , wherein the ACT-4-L-h-1 ligand polypeptide is immobilized to a solid surface.  
     
     
         48 . A method of inducing an immune response to a selected antigen comprising: 
 administering the monoclonal antibody of  claim 25  to a patient; and    exposing the patient to the selected antigen.    
     
     
         49 . A method of monitoring activated CD4 +  T-cells, the method comprising: 
 contacting a tissue sample from a patient with an ACT-4-L ligand polypeptide that specifically binds to an extracellular domain of the ACT-4-h-1 receptor; and    detecting specific binding between the ACT-4-L ligand polypeptide and the tissue sample to indicate the presence of the activated CD4 +  T-cells.    
     
     
         50 . A method of inhibiting infection of CD4 +  T-cells by a human immune deficiency virus, the method comprising contacting the CD4 +  T-cells with an antibody that specifically binds to an extracellular domain of the ACT-4 receptor.