Transgenic transchromosomal rodents for making human antibodies

1. A method for generating a human sequence antibody or fragment thereof that binds to a predetermined antigen, the method comprising:

isolating antibody V region nucleic acid sequences from a transgenic mouse, the transgenic mouse comprising two human immunoglobulin loci, wherein one of the human immunoglobulin loci is a human heavy chain locus and the other human immunoglobulin loci is a human light chain locus; wherein the human heavy chain locus is carried by transchromosome SC20 and the human light chain locus is carried by a transgene integrated into the genome of said mouse, and wherein an endogenous mouse heavy chain locus and at least one endogenous mouse light chain locus are inactivated, the transgenic mouse having been immunized with a predetermined antigen;

cloning the isolated V regions into a vector to generate an expression library; and

expressing the library to identifiy V region nucleic acid sequences that encode a human antibody sequence or fragment thereof that binds to the predetermined antigen.

2. A method for generating a human sequence antibody or fragment thereof that binds to a predetermined antigen, the method comprising:

cloning a nucleic acid sequence encoding at least one human antibody V region into an expression vector,

wherein the isolated nucleic acid sequences are from a B cell of a transgenic mouse, the transgenic mouse comprising two human immunoglobulin loci, wherein one of the human immunoglobulin loci is a human heavy chain locus and the other human immunoglobulin loci is a human light chain locus; wherein the human heavy chain locus is carried by transchromosome SC20 and the human light chain locus is carried by a transgene integrated into the genome of said mouse, and wherein an endogenous mouse heavy chain locus and at least one endogenous mouse light chain locus are inactivated, the transgenic mouse having been immunized with a predetermined antigen; or from hybridomas generated by fusion of the B cell and an immortalized cell;

introducing the vector into a host cell; culturing the host cell under conditions such that the nucleic acid sequences are expressed; and isolating the human sequence antibody or fragment thereof from said host cell or culture medium thereof.

3. The method of claim 2 wherein the nucleic acid sequences are cDNA.

4. The method of claim 2 wherein the nucleic acid sequences are isolated by PCR.

5. The method of claim 2 wherein nucleic acid sequences are isolated by cDNA library screening using at least one nucleic acid probe.

6. The method of claim 2 wherein the nucleic acid sequences are isolated by phage display library screening.

7. The method of claim 2 wherein the nucleic acid sequences encode full length human antibody sequences.

8. The method of claim 2 wherein the isolated human sequence antibody isotype is different from the isotype of antibody producing cells of the immunized transgenic mouse.

9. The method of claim 2 wherein the transgenic mouse further comprises a mutation in a gene that increases the immune response to autoantigen.

10. The method of claim 9 wherein the mutation inactivates the Fc-γIIB gene.