title: A competitive enzyme-linked immunoassay (ELISA) for the measurement of soluble human interleukin-2 receptors (IL-2R, Tac protein).
abstract: A solid-phase, competition enzyme-linked immunosorbent assay (ELISA) was established for the quantitative measurement of soluble (human) interleukin-2 receptors (IL-2R). The ladder of reagents from the solid phase up consisted of: (1) recombinant DNA-derived, purified IL-2R, (2) sample-containing soluble IL-2R and fluorescein isothiocyanate (FITC)-conjugated monoclonal antibody, 7G7/B6, directed against the IL-2R, (3) alkaline phosphatase-conjugated rabbit anti-FITC, and (4) substrate. This ELISA was compared with a 'sandwich' ELISA for soluble IL-2R. The competitive ELISA was less sensitive than the 'sandwich' assay, being capable of measuring 5000 versus 31 U/ml, respectively. While both anti-Tac and 7G7/B6 in the IL-2R-containing sample inhibited the 'sandwich' assay, only 7G7/B6 inhibited the competition assay. Anti-mouse immunoglobulin enhanced the 'sandwich' assay and inhibited the competitive assay; both effects could be overcome by the addition of normal mouse immunoglobulin in the sample buffer. Studies of a patient's serum receiving anti-Tac as therapy for the adult T cell leukemia demonstrated that rises in the level of IL-2R occurring with anti-Tac therapy, as measured with the competition assay, were masked in the 'sandwich' assay. This competition ELISA will be useful for measuring soluble IL-2R levels in patients receiving anti-Tac as therapy for various immunologic disorders.
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology / Q000627:therapeutic use; D001667:Binding, Competitive; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D007945:Leukemia, Lymphoid / Q000628:therapy; D011971:Receptors, Immunologic / Q000032:analysis* / Q000276:immunology; D015375:Receptors, Interleukin-2; D012995:Solubility
chemical_list: D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2