The immune system recognizes and destroys a wide range of potential pathogens and foreign substances. To avoid immune cell–mediated attack of one’s own tissues, referred to as ‘horror autotoxicus’ over 100 years ago, the body has elaborate control systems in place. In the November issue of Nature Immunology, scientists show how regulatory T cells instruct other immune cells to avoid such masochistic behavior.
Italian researchers led by Paolo Puccetti now show that two types of immune cells conspire to prevent other immune system cells from becoming activated and going into ‘attack mode’. T regulatory cells (T regs) calm the immune system by preventing antigen-presenting cells (APCs) from calling the alarm. The T regs cleverly instruct these APCs to secrete an enzyme called indoleamine 2,3-dioxygenase (IDO for short), which destroys the essential amino acid tryptophan. Without tryptophan, T cells cannot attack. APCs that had been exposed to T regs in culture were found to suppress immune responses when transferred into mice. T regs do this by enhancing IDO synthesis by the APCs, so this could be a major way by which the T regs control auto-aggressive immune cells. These new data might pave the way for new therapies to combat autoimmune diseases.
University of Perugia, Italy
Tel: +39 075 585 7463
Also available online.
(C) Nature Immunology Press Release.
Message posted by: Trevor M. D'Souza