Abstract: The present invention relates to the use of a reagent that binds specifically to a predetermined ligand, contains one or more antibody constant region epitopes, and is uniform in specificity and affinity. The reagent can be produced continually, in the manufacture of calibrators (standards) and/or controls for diagnostic kits designed to qualitatively or quantitatively measure antibodies specific for a desired ligand. For example, the present invention encompasses recombinant mouse-human chimeric antibodies which may be used as calibrators (standards) and/or positive controls in assays and kits which measure human antibodies. Any species may be used in creating the chimeric antibodies, and the presence of any corresponding species of antibody may be detected.