Compositions and methods including recombinant B lymphocyte cell line including at least one endogenous gene expressing at least one endogenous membrane immunoglobulin reactive to a first antigen and including at least one exogenously incorporated nucleic acid expressing at least one exogenous secreted immunoglobulin reactive to a second antigen

1. A method for treating a disease in a vertebrate subject with an immunotherapeutic product comprising:

isolating from a vertebrate subject exposed to at least one first antigen, a B lymphocyte expressing at least one first immunoglobulin that is an endogenous membrane immunoglobulin reactive to the at least one first antigen;

introducing into the isolated B lymphocyte at least one of at least one exogenous nucleic acid encoding at least one second immunoglobulin that is an exogenous secreted immunoglobulin reactive to at least one second antigen to produce a recombinant B lymphocyte cell line;

selecting the recombinant B lymphocyte line expressing the at least one exogenous secreted immunoglobulin reactive to the at least one second antigen; and

administering a therapeutically effective amount of said recombinant B lymphocyte cell line to one or more vertebrate subjects afflicted with disease.

2. The method of claim 1 , further comprising:

exposing the recombinant B lymphocyte cell line to the at least one first antigen; and

assaying production of the at least one exogenous secreted immunoglobulin reactive to the at least one second antigen in the recombinant B lymphocyte cell line.

3. The method of claim 1 , wherein the at least one first antigen and the at least one second antigen are different epitopes of a single antigenic polypeptide.

4. The method of claim 1 wherein:

the isolated B lymphocyte cell line is configured to disrupt expression of an endogenous secreted immunoglobulin reactive to the at least one first antigen.

5. The method of claim 1 , further comprising:

introducing into the isolated recombinant B lymphocyte cell line at least one exogenous nucleic acid encoding at least one secreted immunoglobulin reactive to a third antigen to produce at least one second recombinant B lymphocyte cell line; and

selecting the at least one second recombinant B lymphocyte cell line expressing the at least one exogenous secreted immunoglobulin reactive to at least one third antigen and expressing the at least one exogenous secreted immunoglobulin reactive to the at least one second antigen; and

assaying production of the exogenous secreted immunoglobulin reactive to at least one third antigen in the at least one second recombinant B lymphocyte cell line.

6. The method of claim 5 , further comprising:

exposing the at least one second recombinant B lymphocyte cell line to the at least one first antigen; and

assaying production of the exogenous secreted immunoglobulin reactive to the at least one third antigen in the at least one second recombinant B lymphocyte cell line.

7. The method of claim 1 , further comprising:

introducing into the recombinant B lymphocyte cell line at least one exogenous nucleic acid encoding at least one membrane immunoglobulin reactive to the third antigen to produce at least one second recombinant B lymphocyte cell line;

selecting the at least one second recombinant B lymphocyte cell line expressing the at least one exogenous membrane immunoglobulin reactive to the third antigen.

8. The method of claim 1 , further comprising:

exposing the recombinant B lymphocyte cell line to the at least one first antigen, and

assaying production of the exogenous secreted immunoglobulin reactive to the at least one second antigen in the recombinant B lymphocyte cell line.

9. The method of claim 8 , further comprising:

harvesting the secreted immunoglobulin reactive to the at least one second antigen from the recombinant B lymphocyte cell line or from a culture of the recombinant B lymphocyte cell line.

10. The method of claim 5 , further comprising:

exposing the at least one second recombinant B lymphocyte cell line to the at least one first antigen, and

assaying production of the exogenous secreted immunoglobulin reactive to the third antigen in the at least one second recombinant B lymphocyte cell line.

11. The method of claim 10 , further comprising:

harvesting the exogenous secreted immunoglobulin reactive to the third antigen from the recombinant B lymphocyte cell line or from a culture of the recombinant B lymphocyte cell line.

12. The method of claim 1 further comprising:

exposing the vertebrate subject to the at least one first antigen.

13. The method of claim 12 , further comprising assaying production of the one or more exogenous secreted immunoglobulin reactive to the at least one second antigen by administering the at least one first antigen to the vertebrate subject.

14. The method of claim 1 , wherein

the isolated B lymphocyte cell comprises at least one of naïve B lymphocytes, immature B lymphocytes, transitional B lymphocytes, mature B lymphocytes, follicular B lymphocytes, memory B lymphocytes, plasmablasts, or plasma cells.

15. The method of claim 1 , wherein the recombinant B lymphocyte cell is autologous to one of the one or more vertebrate subjects.

16. The method of claim 1 , wherein the recombinant B lymphocyte cell is allogeneic to the one or more vertebrate subjects.