A sensitive, rapid assay for the detection of human granulocyte-macrophage colony stimulating factor

Several monoclonal antibodies were developed against recombinant human granulocyte colony stimulating factor (hu-GM-CSF). All were reactive to the protein by enzyme linked immunoabsorbent assay (ELISA), and one, 1G2 was capable of immunoprecipitating significant levels of radiolabeled hu-GM-CSF. When 1G2 and a second GM-CSF reactive monoclonal antibody, 3G11, were used in a double determinant assay, the level of detection of hu-GM-CSF in solution was approximately 500 ng/ml. Additional sensitivity was gained by using affinity purified rabbit polyclonal antibodies, together with the monoclonal 1G2. Using such a configuration in a double determinant assay one could detect 10-90 ng/ml of human-GM-CSF in solution with no reactivity observed to CSF-1 or granulocyte-CSF.