Polypeptides that modulate the interaction between cells of the immune system

1. A polypeptide that binds CD28 and reduces, inhibits, prevents and/or blocks the interaction between CD80-Fc or CD86-Fc and cell-displayed CD28, and that comprises three stretches of amino acid residues chosen from:

SEQ ID NOs: 518, 530, and 542;

SEQ ID NOs: 519, 531, and 543;

SEQ ID NOs: 520, 532, and 544;

SEQ ID NOs: 521, 533, and 545;

SEQ ID NOs: 522, 534, and 546; and

SEQ ID NOs: 523, 535, and 547.

2. A polypeptide according to claim 1 , that can specifically bind CD28 with a dissociation constant (K D ) of 10 −5 to 10 −12 moles/liter or less, 10 −7 to 10 −12 moles/liter or less or 10 −8 to 10 −12 moles/liter.

3. A polypeptide according to claim 1 , that can specifically bind CD28 with a rate of association (k on -rate) of between 10 2 M −1 s −1 to about 10 7 M −1 s −1 , between 10 3 M −1 s −1 and 10 7 M −1 s −1 , between 10 4 M −1 s −1 and 10 7 M −1 s −1 , or between 10 5 M −1 s −1 and 10 7 M −1 s −1 .

4. A polypeptide according to claim 1 , that can specifically bind CD28 with a rate of dissociation (k off rate) between 1 s −1 and 10 −6 s −1 , between 10 −2 s −1 and 10 −6 s −1 , between 10 −3 s −1 and 10 −6 s −1 , or between 10 −4 s −1 and 10 −6 s −1 .

5. A polypeptide according to claim 1 , that can specifically bind CD28 with an affinity less than 500 nM, less than 200 nM, less than 10 nM, or less than 500 pM.

6. A polypeptide according to claim 1 , that comprises an immunoglobulin fold or that under suitable conditions is capable of forming an immunoglobulin fold.

7. A polypeptide according to claim 1 , that essentially consists of a light chain variable domain sequence or of a heavy chain variable domain sequence.

8. A polypeptide according to claim 1 , that essentially consists of a domain antibody, a single domain antibody, a V HH , a humanized V HH , or a camelized V H .

9. A polypeptide according to claim 1 , that essentially consists of a V HH , a humanized V HH , or a camelized V H that

has at least 80% amino acid identity with at least one of the amino acid sequences of SEQ ID NO's: 1 to 22, in which for the purposes of determining the degree of amino acid identity, the amino acid residues that form the CDR sequences are disregarded;

and in which:

one or more of the amino acid residues at positions 11, 37, 44, 45, 47, 83, 84, 103, 104 and 108 according to the Kabat numbering are chosen from

at position 11: L, M, S, V, W,

at position 37: F, Y, H, I, L, V,

at position 44: G, E, A, D, Q, R, S, L,

at position 45: L, R, C, I, L, P, Q, V,

at position 47: W, L, F, A, G, I, M, R, S, V, Y,

at position 83: R, K, N, E, G, I, M, Q, T,

at position 84: P, A, L, R, S, T, D, V,

at position 103: W, P, R, S,

at position 104: G, D, and

at position 108: Q, L, R.

10. A polypeptide according to claim 1 , that essentially consists of a V HH , a humanized V HH , or a camelized V H that

i) has at least 80% amino acid identity with at least one of the amino acid sequences of SEQ ID NO's: 266-285, 347-351, 394-399, 449-455, 505-511, 554-559 or 1288-1391 in which for the purposes of determining the degree of amino acid identity, the amino acid residues that form the CDR sequences are disregarded;

and in which:

one or more of the amino acid residues at positions 11, 37, 44, 45, 47, 83, 84, 103, 104 and 108 according to the Kabat numbering are chosen from

at position 11: L, M, S, V, W,

at position 37: F, Y, H, I, L, V,

at position 44: G, E, A, D, Q, R, S, L,

at position 45: L, R, C, I, L, P, Q, V,

at position 47: W, L, F, A, G, I, M, R, S, V, Y,

at position 83: R, K, N, E, G, I, M, Q, T,

at position 84: P, A, L, R, S, T, D, V,

at position 103: W, P, R, S,

at position 104: G, D, and

at position 108: Q, L, R.

11. A polypeptide according to claim 1 , that essentially consists of a humanized V HH .

12. A polypeptide that cross-blocks the binding to CD28 by at least one of the polypeptides according to claim 1 .

13. A polypeptide that is cross-blocked from binding to CD28 by at least one of the polypeptides according to claim 1 .

14. A compound or a construct, that comprises or essentially consists of one or more polypeptides according to claim 1 , and optionally further comprises one or more other groups, residues, moieties or binding units, optionally linked via one or more linkers.

15. A compound or a construct according to claim 14 , in which said one or more other groups, residues, moieties or binding units are chosen from the group consisting of domain antibodies, single domain antibodies, V HH s, humanized V HH s or camelized V H s.

16. A compound or a construct according to claim 14 , in which said one or more polypeptides are chosen from the group consisting of domain antibodies, single domain antibodies, V HH s, humanized V HH s or camelized V H s.

17. A compound or a construct according to claim 14 , which is a multivalent construct.

18. A compound or a construct according to claim 14 , which is a multispecific construct.

19. A compound or a construct according to claim 14 , in which said one or more other groups, residues, moieties or binding units provide the compound or construct with increased serum half-life, compared to the polypeptide without the one or more other groups, residues, moieties or binding units.

20. A compound or a construct according to claim 19 , in which said one or more other groups, residues, moieties or binding units that provide the compound or construct with increased serum half-life is chosen from the group consisting of serum proteins or fragments thereof, binding units that can bind to serum proteins, an Fc portion, and small proteins or peptides that can bind to serum proteins.

21. A compound or a construct according to claim 19 , in which said one or more other groups, residues, moieties or binding units that provide the compound or construct with increased serum half-life are selected from the group consisting of human serum albumin and fragments thereof.

22. A compound or a construct according to claim 20 , in which said one or more other groups, residues, moieties or binding units that provides the compound or construct with increased serum half-life are selected from the group consisting of binding units that can bind to serum albumin, human serum albumin, and a serum immunoglobulin.

23. A compound or a construct according to claim 19 , in which said one or more other groups, residues, moieties or binding units that provides the compound or construct with increased serum half-life are selected from the group consisting of domain antibodies, single domain antibodies, V HH s, humanized V HH s and camelized V H s that can bind to serum albumin, human serum albumin, or a serum immunoglobulin.

24. A compound or a construct according to claim 19 , in which said one or more other groups, residues, moieties or binding units that provides the compound or construct with increased serum half-life is a V HH , a humanized V HH or a camelized V H that can bind to serum albumin, human serum albumin, or a serum immunoglobulin.

25. A compound or a construct according to claim 19 , that has a serum half-life that is at least 1.5 times, at least 2 times, at least 5 times, at least 10 times or more than 20 times, greater than the half-life of the polypeptide without the one or more other groups, residues, moieties or binding units.

26. A compound or a construct according to claim 19 , that has a serum half-life that is increased with more than 1 hours, more than 2 hours, more than 6 hours, more than 12 hours, or more than 24, 48 or 72 hours, compared to the polypeptide without the one or more other groups, residues, moieties or binding units.

27. A compound or a construct according to claim 19 , that has a serum half-life in human of at least about 12 hours, at least 24 hours, at least 48 hours, at least 72 hours; of at least 5 days, at least 9 days, 9 to 14 days, at least about 10 days, about 10 to 15 days, at least about 11 days, about 11 to 16 days, at least about 12 days, about 12 to 18 days, more than 14 days, or about 14 to 19 days.

28. A monovalent construct, comprising or essentially consisting of one polypeptide according to claim 1 .

29. A composition, comprising at least one polypeptide according to claim 1 .

30. A composition according to claim 29 , which is a pharmaceutical composition, that further comprises at least one pharmaceutically acceptable carrier, diluent or excipient and/or adjuvant, and that optionally comprises one or more further pharmaceutically active polypeptides and/or compounds.

31. A polypeptide according to claim 1 , that is pegylated.

32. A polypeptide that binds CD28 and reduces, inhibits, prevents and/or blocks the interaction between CD80-Fc or CD86-Fc and cell-displayed CD28, and that essentially consists of 4 framework regions (FR1 to FR4, respectively) and 3 complementarity determining regions (CDR1 to CDR3, respectively), in which:

CDR1 is SEQ ID NO: 518, CDR2 is SEQ ID NO: 530, and CDR3 is SEQ ID NO: 542;

CDR1 is SEQ ID NO: 519, CDR2 is SEQ ID NO: 531, and CDR3 is SEQ ID NO: 543;

CDR1 is SEQ ID NO: 520, CDR2 is SEQ ID NO: 532, and CDR3 is SEQ ID NO: 544;

CDR1 is SEQ ID NO: 521, CDR2 is SEQ ID NO: 533, and CDR3 is SEQ ID NO: 545;

CDR1 is SEQ ID NO: 522, CDR2 is SEQ ID NO: 534, and CDR3 is SEQ ID NO: 546; or

CDR1 is SEQ ID NO: 523, CDR2 is SEQ ID NO: 535, and CDR3 is SEQ ID NO: 547.

33. A polypeptide that cross-blocks the binding to CD28 by at least one of the polypeptides according to claim 32 .

34. A polypeptide that is cross-blocked from binding to CD28 by at least one of the polypeptides according to claim 32 .