The invention relates to artificial modified proteins, preferably fusion proteins, having a reduced 
immunogenicity compared to the parent non-modified molecule when exposed to a species 
in vivo. The invention relates, above all, to novel immunoglobulin fusion proteins which essentially consist of an immunoglobulin molecule or a fragment thereof covalently fused via its C-terminus to the N-terminus of a biologically active non-immunoglobulin molecule, preferably a polypeptide or 
protein or a biologically active fragment thereof. In a specific embodiment, the invention relates to fusion proteins consisting of an Fc portion of an 
antibody which is fused as mentioned to the non-immunological target molecule which elicits biological or pharmacological 
efficacy. The molecules of the invention have 
amino acid sequences which are altered in one or more 
amino acid residue positions but have in principal the same 
biological activity as compared with the non-altered molecules. The changes are made in regions of the molecules which are identified as T-
cell epitopes, which contribute to an 
immune reaction in a living host. Thus, the invention also relates to a novel method of making such fusion proteins by identifying said epitopes comprising calculation of T-
cell epitope values for 
MHC Class II molecule binding sites in 
a peptide by computer-aided methods.