Recombinant human IL-12/IL-23 (p40) (ELISA Std.)

Bioactive IL-12 is a potent regulator of cell-mediated immune responses and key mediator of Th1 cell development. Bioactive IL-12 is secreted by activated B lymphocytes, dendritic cells and macrophages as a 70 kD heterodimeric glycoprotein comprised of disulfide-bonded 35 kD and 40 kD subunits. The p40 protein is also a subunit of IL-23 (p60). The disulfide-linked p40 homodimer can bind to IL-12 receptors and antagonize the activities of bioactive IL-12. IL-12 p40 monomer is secreted in vast excess of IL-12 p70 heterodimer; IL-12 p40 monomer has no activity and is antagonistic to IL-12 p70 with only 1/10th the activity of p40 homodimer. Recombinant human IL-12 p40 monomer contains 306 amino acids. Cytokine detection IL-12, IL-23 and IL-35 share common subunits, utilizing combinations of p40, p19 and p35 proteins. Caution must be used when selecting antibodies and assays when specific identification, measurement, as well as activation state discrimination, is required. 1. Active IL-12 consists of two subunits: p40 + p35. 2. p40 can also exist as a monomer (IL-12 p40) or a homodimer (IL-12 p80). 3. Besides contributing to IL-12, p40 is also found in IL-23, a heterodimer of p40 and p19. 4. Similarly, p35 not only contributes to IL-12, but is also found in the heterodimer IL-35 (p35 and EBI3). Note that assays using antibodies specific for the p40 subunit will be unable to discriminate between the active IL-12, monomeric p40, dimeric p40, and IL-23; likewise, assays using p35 detection alone will pick up both IL-12 (heterodimer) and IL-35.