The invention concerns immune complexes for use in a diagnostic method for detecting and localizing specific cells in a human or animal body by an imaging technique. First antibodies are directed to an antigen located on the surface of said cells. The first antibodies are optionally labeled with first labels. The method comprises that the first antibodies and second antibodies directed to said first antibodies or to the first labels or the first antibodies and ligands specifically binding to the first labels are administered to said human or animal body, wherein said second antibodies or said ligands are labeled with second labels detectable by said imaging technique. The cells are detected and localized in the human or animal body after administration of the first antibodies and second antibodies or of the first antibodies and the ligands by use of the imaging technique. The immune complexes of the invention are formed from the first antibodies and the second antibodies or from the first antibodies and the ligands ex vivo before administration of said immune complexes to the human or animal body.
