Disclosed is a recombinant fusion protein containing an amino-acid sequence which comprises: (a) the Fc section or part of an Fc section of an immunoglobulin as component (A) or a functional variant of component (A); (b) the extracellular part of a TNF ligand or a partial sequence of the extracellular part of a TNF ligand as component (B) or a functional variant of component (B); and optionally (c) a transition area between component (A) and component (B), containing a linker.