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

1. A method for the production of a soluble Fc-receptor, said method comprising the following steps:

a) cultivating in a cultivation medium a cell comprising a nucleic acid encoding a fusion polypeptide of 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 human IgG1 heavy chain polypeptide comprising the amino acid sequence of SEQ ID NO: 1 with the mutations L234A, L235A and P329G, human IgG4 heavy chain polypeptide comprising the amino acid sequence of SEQ ID NO: 15 with the mutations S228P and L235E, and human IgG1 heavy chain polypeptide comprising the amino acid sequence of SEQ ID NO: 1 with the mutations 1253A, H310A, and H435A,

b) recovering said fusion polypeptide from said cell or said cultivation medium, and

c) optionally, cleaving said fusion polypeptide with a protease, thereby producing said soluble Fc-receptor.

2. The method of claim 1 , wherein said fusion polypeptide has 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 method of claim 1 or 2 , wherein said soluble Fc receptor comprises two fusion polypeptides of Formula I or Formula II.