Specificity Reference Reagent Purified IgG fraction of polyclonal goat antiserum to human IgD, Fc specific. As unlabelled secondary antibody for indirect detection of IgD in human cell, tissue substrates and body fluids in immunofluorescence and immunoenzyme assay methods; for the production of immunoconjugates with a selected marker; to prepare insoluble immunoaffinity adsorbents by coupling to an artificial carrier; as catching or detecting antibody reagent in non-isotopic assay methodology (e.g. ELISA) to identify and measure IgD in human serum or other body fluid. When applied in any immunocytochemical or histochemical staining procedure or solid phase coupling technique, the optimum concentration of the IgG preparation should be established. Working dilutions for histochemical and cytochemical use are usually between 1:100 and 1:250; in ELISA and comparable non-precipitating antibody-binding assays between 1:500 and 1:5,000.