Method for producing soluble FcR as Fc-fusion with inert immunoglobulin Fc-region and uses thereof

1. A fusion polypeptide comprising the formula (I):

R1-FC-R2  (formula I)

wherein:

R1 denotes a first Fc-receptor,

R2 denotes a second Fc-receptor, and

FC denotes a heavy chain Fc-region polypeptide,

wherein R1 or R2 or both are present,

wherein FC does not bind to R1 and/or R2,

wherein FC is selected from:

(i) human IgG1 heavy chain polypeptide comprising the amino acid sequence of SEQ ID NO: 3 with

(1) the mutations L234A, L235A, and P329G,

(2) the mutations I253A, H310A, and H435A,

(3) the mutation T366W and optionally the mutation S354C,

(4) the mutations T366S, L368A, and Y407V, and optionally the mutation Y349C,

(5) the mutations L234A, L235A, P329G, T366W, and optionally the mutation S354C,

(6) the mutations I253A, H310A, H435A, T366W, and optionally the mutation S354C,

(7) the mutations L234A, L235A, P329G, T366S, L368A, and Y407V, and optionally the mutation Y349C,

(8) the mutations I253A, H310A, H435A, T366S, L368A, and Y407V, and optionally the mutation Y349C,

(9) the mutations L234A, L235A, P329G, I253A, H310A, H435A, T366W, and optionally the mutation S354C, or

(10) the mutations L234A, L235A, P329G, I253A, H310A, H435A, T366S, L368A, and Y407V, and optionally the mutation Y349C,

and

(ii) human IgG4 heavy chain polypeptide comprising the amino acid sequence of SEQ ID NO 15 with

(1) the mutations S228P and L235E,

(2) the mutation T366W and optionally the mutation S354C,

(3) the mutations T366S, L368A, and Y 407V, and optionally the mutation Y349C,

(4) the mutations S228P, L235E, T366W, and optionally the mutation S354C, or

(5) the mutations S228P, L235E T366S, L368A, Y407V, and optionally the mutation Y349C.

2. The fusion polypeptide of claim 1 , wherein said fusion polypeptide comprises the formula II:

R1-CS1-L1-CS2-FC-CS3-L2-CS4-R2  (formula II)

wherein:

R1 denotes a first Fc-receptor,

R2 denotes a second Fc-receptor,

FC denotes a heavy chain Fc-region polypeptide,

CS1 denotes a first cleavage site,

CS2 denotes a second cleavage site,

CS3 denotes a third cleavage site,

CS4 denotes a fourth cleavage site,

L1 denotes a first linker, and

L2 denotes a second linker,

wherein R1 or R2 or both are present,

wherein any one of CS1, CS2, CS3, CS4 can independently of each other be present or absent,

wherein L1 and L2 can independently of each other be present or absent, and

wherein FC does not bind to R1 and/or R2.

3. The fusion polypeptide as in either claim 1 or claim 2 , wherein R1 and R2 are independently of each other selected from human Fc gamma-receptor, human neonatal Fc-receptor, murine Fc-receptor, and rabbit neonatal Fc-receptor.

4. A dimeric fusion polypeptide comprising a first fusion polypeptide and a second fusion polypeptide as in either claim 1 or claim 2 .

5. The fusion polypeptide of claim 4 , wherein:

a) R1 and R2 of said first fusion polypeptide and said second fusion polypeptide are identical,

b) R1 and R2 of said first fusion polypeptide are identical, R1 and R2 of said second fusion polypeptide are identical but different from R1 and R2 of said first fusion polypeptide, or

c) R1 of said first fusion polypeptide and said second polypeptide are identical and R2 of said first fusion polypeptide and said second fusion polypeptide are identical but different from R1.