Patent ID: 7144986

Claim:
An isolated polypeptide consisting of a fragment of the IL-6 receptor, wherein said polypeptide inhibits binding of IL-6 ligand with the IL-6 receptor under physiological conditions, and wherein (a) said fragment comprises the amino acid sequence I A I V L R F (SEQ ID NO: 13), which sequence can further comprise one amino acid substitution selected from the following; I, L, or V is substituted with any synthetic or naturally-occurring amino acid residue having a side-chain consisting of a C 1 –C 6 straight-chain or branched alkyl moiety; R is substituted with any synthetic or naturally-occurring amino acid residue having a side-chain that is basic under physiological conditions; A is substituted with glycinyl, isoleucinyl, leucin.yl, valinyl, norleucinyl, norvitlinyl, Sarcosinyl, β-alaninyl, and α-aminoisobutyryl; F is substituted with tyrosinyl, tryptophanyl, and α-aminoisobutyryl, and (b) said polypeptide comprises less than 200 contiguous amino acid residues.