The invention relates to antibodies against the human La protein and to their use in immunotargeting, in particular the immunotargeting of tumor cells. The object of the invention is to provide improved antibodies which bind universal target structures on the surface of tumor cells, and to provide novel anti-La antibodies, in particular with a high affinity for La, a universal target structure on tumor cells, which make it possible to use the antibodies as recombinant fragments for immunotargeting. The invention comprises recombinant antibodies comprising: (i) a binding unit of an antibody which specifically binds to an epitope of a human nuclear antigen, preferably human La protein, and (ii) a binding unit of an antibody which specifically binds to an effector cell or of a ligand which specifically binds to an effector cell. The invention furthermore comprises novel antibodies which specifically bind the human La protein.