Human IL-23 ELISA Set, for supernatant only

The usefulness of sandwich ELISAs (enzyme-linked immunosorbent assays) in cytokine biology is evident from the many reports published on this subject. The assay requires two antibodies (either mono- or polyclonal antibodies) that bind with high affinity to different sites on the cytokine molecule. One of the antibodies is immobilized to the wells of a 96-well microtiter plate. This so-called capture or coating antibody functions to selectively immobilize the cytokine from crude protein preparations. The second antibody (detection antibody) is labeled with biotin and binds to a different site on the cytokine molecule. Biotin allows the antibody to interact with streptavidin molecules. By using HRP (horseradish peroxidase)-labeled streptavidin, the cytokine can now quantitatively be determined by enzymaticconversion of a HRP-specific substrate to a colored product. Since many biotin molecules can be coupled to the detector antibody, several HRP molecules are bound. The enzyme activity is subsequently further increased by using complexes (polymers) of HRP-streptavidin. This results in an extreme sensitive assay with a detection limit within the low picogram range (ca.5 pg/ml).