The immune system is powerful enough to provide protection from disease. Unfortunately, to act decisively the cells of the immune system have to be able to discriminate between self and non-self. Poor discrimination can lead to autoimmunity, cancer or infection. New approaches promise the precise use of interleukins, to reset self-recognition, eliminate a wide range of diseases and liberalize organ transplantation.
IL-2 is the Cytokine Responsible for Suppression of Autoimmunity -- Tolerance
Self/non-self discrimination is dependent on cellular communication and much of that communication takes place via small proteins called interleukins. First and foremost among the interleukins is interleukin-2 (IL-2). IL-2 is made by cells of the immune system, lymphocytes. Mice that are either defective in producing IL-2 or the lymphocyte receptor for IL-2, IL2R alpha, also called CD25, rapidly develop autoimmune diseases, such as type I diabetes or inflammatory bowel disease. Thus IL-2 is necessary for both effective immunological defenses against pathogens and suppression of immune attacks on self tissues, i.e. autoimmunity.
IL-2 Balance Achieved with Complex of IL-2 and Anti-IL-2 AntibodiesDirect injection of IL-2 has some impact on cancers, but is very difficult to control. This should be expected, because local environments should determine if the IL-2 will stimulate aggressive immunological attacks or development of regulatory T cells, Tregs, that produce tolerance.
More subtle control is achieved by using antibodies that bind to particular regions of the IL-2. The resulting IL-2/anti-IL-2 complexes can be used to stimulate immunological reactions to an antigen, which is useful for vaccines, or can stimulate tolerance for use in organ transplantation.
Future applications may be in the cure of a wide variety of autoimmune diseases, e.g. type I diabetes, inflammatory bowel diseases, allergies, asthma; degenerative diseases, such as arthritis or athersclerosis, and cancers.
reference:
Webster KE, Walters S, Kohler RE, Mrkvan T, Boyman O, Surh CD, Grey ST, Sprent J. 2009. In vivo expansion of T reg cells with IL-2-mAb complexes: induction of resistance to EAE and long-term acceptance of islet allografts without immunosuppression. J Exp Med. Mar 30. [Epub ahead of print]