Universal GM-CSF expressing bystander human K562 cell line

1. A universal bystander cell line, which: (i) is the human cell line K562 or a subclone thereof, which is modified to lack major histocompatibility class I (MHC-I) antigens and major histocompatibility class II (MHC-II) antigens, and (ii) is modified by introduction of a nucleic acid molecule comprising a nucleic acid sequence encoding an immunomodulatory cytokine operably linked to an inducible promoter, wherein the universal bystander cell line expresses about 500 ng or greater of the immunomodulatory cytokine/10 6 cells/24 hours upon being induced.

2. The universal bystander cell line of claim 1 , wherein the immunomodulatory cytokine is selected from the group consisting of granulocyte macrophage-colony stimulating factor (GM-CSF) and interleukin-2.

3. The universal bystander cell line of claim 1 , wherein the inducible promoter is selected from the group consisting of the IL-8 promoter and the 6-16 promoter.

4. The universal bystander cell line of claim 1 , wherein the immunomodulatory cytokine is granulocyte macrophage-colony stimulating factor (GM-CSF).

5. The universal bystander cell line of claim 4 , which expresses about 1,000 ng or greater GM-CSF/10 6 cells/24 hours upon being induced.

6. A composition comprising the universal bystander cell line of claim 4 and a cancer antigen.

7. A composition comprising

a universal bystander cell line, which: (i) is the human cell line K562 or a subclone thereof, which is modified to lack major histocompatibility class I (MHC-I) antigens and major histocompatibility class II (MHC-II) antigens, and (ii) is modified by introduction of a nucleic acid molecule comprising a nucleic acid sequence encoding granulocyte macrophage-colony stimulating factor (GM-CSF) operably linked to a promoter, wherein the universal bystander cell line expresses about 500 ng or greater GM-CSF/10 6 cells/24 hours;

a cancer antigen; and

an adjuvant.

8. The composition of claim 7 wherein the cancer antigen is a cell-surface antigen and the universal bystander cell line is genetically modified to express said cell-surface antigen.

9. A method of stimulating an immune response to a cancer in a human patient, which method comprises administering to said patient the composition of claim 7 , wherein said cancer antigen is an antigen of said cancer and wherein said composition is irradiated, whereupon administration of said composition, an immune response to said cancer is stimulated.

10. The method of claim 9 , wherein said cancer antigen is a cell of said cancer.

11. In a method of cancer immunotherapy, the improvement comprising administering to a human patient having a cancer the composition of claim 7 , wherein said cancer antigen is an antigen of said cancer and wherein said composition is irradiated.

12. The composition of claim 7 wherein said promoter is a cytomegalovirus promoter.

13. The composition of claim 12 , wherein said universal bystander cell line expresses about 1,000 ng or greater GM-CSF/10 6 cells/24 hours.

14. The universal bystander cell line of claim 1 , wherein said nucleic acid molecule further comprises a nucleic acid sequence encoding hygromycin resistance operably linked to a promoter and said universal bystander cell line is selected by growth in a culture medium comprising about 400 ug/ml or greater hygromycin.

15. A composition comprising the universal bystander cell line of claim 1 and a cancer antigen.

16. A method of stimulating an immune response to a cancer in a human patient, which method comprises administering to said patient the composition of claim 6 , wherein said cancer antigen is an antigen of said cancer and wherein said composition is irradiated, whereupon administration of said composition, an immune response to said cancer is stimulated.

17. The method of claim 16 , wherein said cancer antigen is a cell of said cancer.