Human interleukin 2. Quantitation by a sensitive radioimmunoassay.
Using polyclonal and monoclonal antibodies to human recombinant IL-2 (rIL-2), we developed a sensitive radioimmunoassay (RIA) for quantitation of human IL-2. In this assay, microtitration plates pre-coated with an anti-rIL-2 monoclonal antibody (35H10), recognizing residues 59-72 of human IL-2, are incubated with serial dilutions of test samples. Captured IL-2 is quantitated by adding an affinity-purified rabbit anti-rIL-2 antibody followed by an 125I-labeled goat anti-rabbit IgG. Antibodies to chemically synthesized IL-2 peptides could replace the polyspecific rabbit anti-rIL-2 antibody as the second specific reagent in the assay. This configuration was more sensitive than others tested, approaching the level of detection of the conventional IL-2 bioassay, thus allowing detection of as little as 100-200 pg IL-2. Serum or plasma fluids, however, inhibited the assay, reducing its sensitivity by approximately 5-fold. This RIA correlated well with the conventional bioassay in measuring IL-2 levels in sera from IL-2-treated patients. This, and similar, RIAs may serve as a useful adjunct or alternative to the conventional IL-2 bioassay in detecting and quantitating human IL-2 in culture supernatants and clinical samples.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000032:analysis; D001666:Binding Sites, Antibody; D002460:Cell Line; D003601:Cytotoxicity Tests, Immunologic; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007376:Interleukin-2 / Q000032:analysis* / Q000276:immunology / Q000378:metabolism; D011817:Rabbits; D011863:Radioimmunoassay / Q000379:methods*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
D000911:Antibodies, Monoclonal; D007376:Interleukin-2