The invention relates to a molecular complex for targeting the antigen towards cells comprising antigens, including at least one antigen associated with at least two ligands of surface molecules of cells comprising antigens, said complex including at least one first ligand of a sulphated sugar of the glycosaminoglycan family and a second ligand of a specific surface molecule of cells comprising antigens, and said first ligand being covalently bonded with said antigen and/or said second ligand.