The invention relates to polypeptides comprising, as constituent A, at least three monomers of a member of the TNF ligand family and, as constituent B, at least two peptide linkers that link the monomers of the member of the TNF ligand family to one another. The invention also relates to the use of these polypeptides for treating diseases and for producing a medicament or a vaccine. The invention also relates to methods for producing and isolating these polypeptides, to nucleic acids that code for these polypeptides, to vectors containing these nucleic acids, to host cells transfected with these vectors, and to pharmaceutical compositions containing these inventive objects. Finally, the invention relates to methods for the extracorporeal manipulation, depletion and/or removal of components contained in body fluids, e.g. by means of apheresis.