Disclosed is a complex, characterized in that it comprises: - one fusion polypeptide that comprises in N- to C-terminal direction (i) a T-cell response eliciting peptide, (ii) a &bgr；2-microglobulin, and (iii) the extracellular domains &alpha；1, &alpha；2, and &alpha；3 of a class I MHC molecule, and - two polypeptide chains, which are linked by one or more disulfide bonds, wherein the first disulfide-linked polypeptide chain comprises in N- to C-terminal direction (i) an immunoglobulin light or heavy chain variable domain, (ii) an immunoglobulin light or heavy chain constant domain, and (iii) an antibody heavy chain hinge region polypeptide, and wherein the second disulfide-linked polypeptide chain comprises an antibody heavy chain hinge region polypeptide, wherein the fusion polypeptide is - covalently bound either to the C-terminus or the N-terminus of one of the disulfide-linked polypeptide chains, or - covalently bound to the N-terminus of an antibody variable domain that is the complementary heavy or light chain variable domain to that comprised in the first disulfide-linked polypeptide chain, or - covalently bound to the C-terminus of an antibody constant domain that is the complementary heavy or light chain constant domain to that comprised in the first disulfide-linked polypeptide chain with the proviso that the complex comprises exactly one fusion polypeptide.
