Described are soluble gp130 polypeptide monomers and dimers, wherein, in a preferred embodiment, at least one of the three amino acid residues Thr 102 , Gln 113 or Asn 114 of the N-terminal Ig-like domain of gp130 is mutated to Tyr 102 , Phe 113 or Leu 114 , respectively. These mutations, alone or in combination, specifically enhance binding of gp130 to its ligand complex of interleukin-6 and soluble interleukin-6 receptor, thus increasing the biological activity of the gp130 muteins. In a particularly preferred embodiment, all three mutations are combined in the triple mutein Thr102Tyr/Gln113Phe/Asn114Leu (T102Y/Q113F/N114L). Moreover, a pharmaceutical composition containing said monomers or dimers and various medical uses are described.
