3. Activation of
immunologic responses
In addition to producing the direct DNA damage, radiation can also produce a lot of free radicals, including reactive oxygen species (ROS), and cause indirect damages to normal tissues/organs. The delicate immune system can also be disturbed by this oxidative stress, causing extraordinary number of immunological responses, including the abnormal release of many cytokines.
Cytokines are regulatory proteins released by cells of the immune system. It has been reported that a number of cytokines may be induced by radiation, including tumor necrosis factor alpha (TNF-α), IL-1, IL-4, IL-5, IL-6, IL-8, IL-10, and transforming growth factor beta (TGF-β). The alteration of cytokine levels in blood, skin, or other tissues can cause a number of pharmacological responses.
