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

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.