Altered antibodies and their preparation

Abstract

An altered antibody chain is produced in which the CDR's of the variable domain of the chain are derived from a first mammalian species. The framework-encoding regions of DNA encoding the variable domain of the first species are mutated so that the mutated framework-encoding regions encode a framework derived from a second different mammalian species. The or each constant domain of the antibody chain, if present, are also derived from the second mammalian species. An antibody which is capable of binding to human CD4 antigen is also provided together with a pharmaceutical composition comprising the antibody.

1 . A process for the preparation of an antibody chain in which complementarity determining regions (CDRs) of the variable domain of the antibody chain are derived from a first mammalian species and the framework of the variable domain and, if present, the or each constant domain of the antibody chain are derived from a second different mammalian species, which process comprises: 
 (i) mutating the framework-encoding regions of DNA encoding a variable domain of an antibody chain of the said first species such that the mutated framework-encoding regions encode the said framework derived from the said second species; and    (ii) expressing the said antibody chain utilising the mutated DNA from step (i);    the mutation in step (i) being such that an antibody incorporating the antibody chain expressed in step (ii) retains the binding capability of the antibody from which the CDRs are derived.    
     
     
         2 . A process according to  claim 1 , wherein the framework-encoding regions of DNA encoding the variable domain of an antibody heavy chain are mutated in step (i).  
     
     
         3 . A process according to  claim 1  or  2 , wherein the framework-encoding regions of DNA encoding the variable domain of an antibody light chain are mutated in step (i).  
     
     
         4 . A process according to any one of the preceding claims, wherein the said first species is rat or mouse.  
     
     
         5 . A process according to any one of the preceding claims, wherein the said second species is human.  
     
     
         6 . A process according to any one of the preceding claims, comprising: 
 (a) determining the nucleotide and predicted amino acid sequence of a variable domain of a selected antibody chain of the said first species;    (b) determining the antibody framework to which the framework of the said domain is to be altered;    (c) mutating the framework-encoding regions of DNA encoding the said variable domain such that the mutated framework-encoding regions encode the framework determined upon in step (b).    (d) linking the mutated DNA obtained in step (c) to DNA encoding a constant domain of the said second species and cloning the DNA into an expression vector; and    (e) introducing the expression vector into a compatible host cell and culturing the host cell under such conditions that antibody chain is expressed.    
     
     
         7 . A process according to  claim 6 , in which about the most homologous framework of an antibody chain of a different species is selected in step (b) as the framework to which the framework of the said variable domain is to be altered.  
     
     
         8 . A process according to any one of the preceding claims, wherein the antibody of the said first species is a CD4 antibody.  
     
     
         9 . A process according to any one of the preceding claims, wherein the said antibody chain is co-expressed with a complementary antibody chain and antibody comprising the said two chains is recovered.  
     
     
         10 . An antibody which is capable of binding to human CD4 antigen, in which the CDRs of the light chain of the antibody have the amino acid sequences:  
       
         
           
                 
                 
                 
                 
               
                     
                     
                 
                     
                   CDR1: 
                   LASEDIYSDLA 
                     
                 
                     
                     
                 
                     
                   CDR2: 
                   NTDTLQN 
                 
                     
                     
                 
                     
                   CDR3: 
                   QQYNNYPWT 
                 
                     
                     
                 
             
                
                
                
                
                
                
                
               
            
           
         
       
       in which the CDRs of the heavy chain of the antibody have the amino acid sequences:  
       
         
           
                 
                 
                 
                 
               
                     
                     
                 
                     
                   CDR1: 
                   NYGMA 
                     
                 
                     
                     
                 
                     
                   CDR2: 
                   TISHDGSDTYFRDSVKG 
                 
                     
                     
                 
                     
                   CDR3: 
                   QGTIAGIRH, 
                 
                     
                   and 
                 
                     
                     
                 
             
                
                
                
                
                
                
                
                
               
            
           
         
       
       in which the framework of the variable domain and, if present, the or each constant domain of each chain are derived from a mammalian non-rat species.  
     
     
         11 . An antibody according to  claim 10 , in which the mammalian non-rat species is human.  
     
     
         12 . An antibody according to  claim 11 , in which the variable domain framework of the heavy chain is homologous to the heavy chain variable domain framework of the protein KOL.  
     
     
         13 . An antibody according to  claim 12 , in which the heavy chain variable region has the amino acid sequence shown in the upper line in  FIG. 10  or  12 .  
     
     
         14 . An antibody according to  claim 11 , in which the variable domain framework of the heavy chain is homologous to the heavy chain variable domain framework of the protein NEW.  
     
     
         15 . An antibody according to  claim 14 , in which the heavy chain variable region has the amino acid sequence shown in the upper line of  FIG. 6  or  7 .  
     
     
         16 . An antibody according to any one of  claims 11  to  15 , in which the variable domain framework of the light chain is homologous to the variable domain framework of the protein REI.  
     
     
         17 . An antibody according to  claim 16 , in which the light chain has the amino acid sequence shown in the upper line of  FIG. 3 .  
     
     
         18 . An antibody which is capable of binding to human CD4-antigen in which the CDRs of the light and heavy chain are derived from a non-human mammalian species and the framework of the variable domain and, if present, the or each constant domain of each chain are human, the said antibody having glycosylation characteristic of CHO cells.  
     
     
         19 . A pharmaceutical composition comprising a pharmaceutically acceptable carrier or diluent and, as active ingredient, an antibody as claimed in any one of  claims 10  to  18 .