Cytokines are thought to raise the thermoregulatory set point to cause fever by stimulating the synthesis of the chemical mediator called the prostaglandin. These are secreted by specific cells found in the immune system. These are molecules involved in cell signaling that helps cells to communicate during immune responses and stimulate the cells to inflammation sites or infection and trauma sites. It stimulates synthesis of prostaglandin and then turnover in the thermoregulatory and nonthermoreglatory tissue. These molecules can exist into three forms which are peptide, glycoprotein and protein forms. These substances are classified in many ways because there is no present unified classification system.