Mutant interleukin-2 (IL-2) polypeptides
The present invention relates to mutant IL-2 polypeptides that act as receptor antagonists. The mutant IL-2 polypeptides bind CD 25 but do not activate the IL-2 receptor. Also provided are methods of using the mutant IL-2 polypeptides, for example, to treat a patient who has cancer or a viral infection. The mutant polypeptides can also be used in various delivery systems.
1. A mutant interleukin-2 (IL-2) polypeptide comprising an amino acid sequence set forth in SEQ ID NO:2 and further comprising an amino acid substitution at position 91 and/or position 126 of SEQ ID NO: 2, wherein the polypeptide binds CD25 but does not activate the IL-2 receptor on T regulatory cells.
2. The mutant IL-2 polypeptide of claim 1 , further comprising a mutation at position 69 or position 74 of SEQ ID NO:2.
3. The mutant IL-2 polypeptide of claim 1 , further comprising a heterologous amino acid sequence.
4. The mutant IL-2 polypeptide of claim 3 , wherein the heterologous amino acid sequence increases the circulating half-life of the mutant IL-2 polypeptide, enhances expression of the mutant IL-2 polypeptide, directs cellular localization of the mutant IL-2polypeptide, or serves as a marker or tag.
5. A composition comprising the mutant IL-2 polypeptide of claim 1 and a physiologically acceptable carrier.
6. The mutant IL-2 polypeptide of claim 1 , wherein amino acid residue 91 has been substituted.
7. The mutant IL-2 polypeptide of claim 1 , wherein amino acid residue 126 has been substituted.
8. The mutant IL-2 polypeptide of claim 1 , wherein amino acid residues 91 and 126 have been substituted.
9. The mutant IL-2 polypeptide of claim 1 , wherein arginine is substituted for valine at position 91 and threonine is substituted for glutamine at position 126.
10. The mutant IL-2 polypeptide of claim 1 , wherein arginine is substituted for valine at position 91 and isoleucine is substituted for glutamine at position 126.
11. The mutant IL-2 polypeptide of claim 1 , wherein the mutant polypeptide binds to the IL-2Rα subunit with a K d of less than 28 nM.
12. The mutant IL-2 polypeptide of claim 10 , wherein the mutant polypeptide binds to the IL-2Rα subunit with a K d of less than 25 nM.
13. The mutant IL-2 polypeptide of claim 11 , wherein the mutant polypeptide binds to the IL-2Rα subunit with a K d of less than 5 nM.
14. The mutant IL-2 polypeptide of claim 12 , wherein the mutant polypeptide binds to the IL-2Rα subunit with a K d of less than 1 nM.
15. The mutant IL-2 polypeptide of claim 12 , wherein the mutant polypeptide binds to the IL-2Rα subunit with a K d of less than 500 pM.
16. The mutant IL-2 polypeptide of claim 6 , wherein arginine is substituted for valine at position 91.
17. The mutant IL-2 polypeptide of claim 7 , wherein threonine is substituted for glutamine at position 126.
18. The mutant IL-2 polypeptide of claim 7 , wherein isoleucine is substituted for glutamine at position 126.
19. The mutant IL-2 polypeptide of claim 3 , wherein the heterologous amino acid sequence increases the circulating half-life of the mutant IL-2 polypeptide, enhances expression of the mutant IL-2 polypeptide, directs cellular localization of the mutant IL-2polypeptide, or serves as a marker or tag.
20. The mutant IL-2 polypeptide of claim 3 , wherein the heterologous amino acid sequence is an Fc region of an immunoglobulin, a FLAG epitope, a c-myc epitope, albumin, or an Aga2p agglutinin polypeptide.
21. The mutant IL-2 polypeptide of claim 3 , wherein the heterologous amino acid sequence is the sequence of an antibody or antigen-binding fragment thereof.
22. The mutant IL-2 polypeptide of claim 3 , wherein the heterologous amino acid sequence is a toxin.
23. A composition comprising the mutant IL-2 polypeptide of claim 9 and a physiologically acceptable carrier.
24. A composition comprising the mutant IL-2 polypeptide of claim 10 and a physiologically acceptable carrier.
25. A composition comprising the mutant IL-2 polypeptide of claim 16 and a physiologically acceptable carrier.
26. A composition comprising the mutant IL-2 polypeptide of claim 17 and a physiologically acceptable carrier.
27. A composition comprising the mutant IL-2 polypeptide of claim 18 and a physiologically acceptable carrier.