Enzyme immunoassay for human granulocyte-macrophage colony-stimulating factor using monoclonal antibodies

A set of seven hybridomas producing monoclonal antibodies (MAbs)to the huma n recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) was obtained. The properties of the monoclonal antibodies were characterized, and pairs of MAbs specific to different non-overlapping epitopes of GM-CSF were identified. A sensitive and simple method of two-site ELISA for GM-CSF was developed on the basis of two MAbs. According to this method, one MAb is absorbed onto a microtiter plate and another is labeled with biotin and used for the detection of GM-CSF bound to the first MAb. MAb labeled with b iotin, in its turn, was visualized with the streptavidin-horseradish peroxi dase conjugate. The sensitivity of this test was no less than 0.5 ng/ml, an d a linear dose-response relationship was observed within a concentration i nterval from 0.5 to 32 ng/ml. No cross-reactivity was found with human tumo r necrosis factor-alpha, granulocyte colony-stimulating factor, interleukin -2, or interleukin-3 in this test system.