The invention is directed to a composition, which comprises: (i) a fusion polypeptide comprising a streptavidin (SA) or avidin polypeptide and one or several effector molecule(s), wherein said fusion polypeptide retains the property of SA and avidin polypeptides to bind biotin (ii) biotinylated targeting molecule(s), which are capable of targeting subset(s) of cells and/or cell surface molecule(s), and in particular dendritic cells (DC), subsets of DC and/or surface molecule(s) (including surface receptor(s)) of DC. The combination of the invention is suitable for diagnosing or immunomonitoring a disease in a mammal or in prophylactic treatment and especially in vaccination and in therapy including in immunotherapy.
