Cytokines are a major component of cellular function. They are produced by the immune system, specifically by immune system cells such as helper T cells. Cytokines are also responsible for things such as inflammation. These cytokines are small proteins which are created by the immune cells. Cytokines act as a medium of communication for immune cells. Whenever damage is detected cytokines are responsible for moving other cells to reach the location of the damage.
Cytokines are involved in the pain-signaling process. The reason for this is that they produce a compound called TNF-Alpha, which means that they result in plenty of nerve growth.