Interleukin 6 (IL-6) is an interleukin that acts as both a pro-inflammatory cytokine and an anti-inflammatory myokine. Rat IL-6 cDNA encodes a 211 amino acid (aa) residue precursor polypeptide with a hydrophobic signal peptide that is cleaved to generate the 187 aa residue mature protein. At the protein sequence level, there is approximately 39% identity between rat and human, and 87% identity between mouse and rat IL-6.
IL-6 is secreted by T cells and macrophages to stimulate immune response, e.g. during infection and after trauma, especially burns or other tissue damage leading to inflammation. IL-6 also plays a role in fighting infection, as IL-6 has been shown in mice to be required for resistance against bacteriumStreptococcus pneumoniae.
IL-6 stimulates the inflammatory and auto-immune processes in many diseases such as diabetes, atherosclerosis, depression, Alzheimer’s Disease, systemic lupus erythematosus, multiple myeloma, prostate cancer, Behçet’s disease, and rheumatoid arthritis. Advanced/ metastatic cancer patients have higher levels of IL-6 in their blood.