New Immune System Discovery
The immune system is sort of this big enigma, we know how pieces of it work, but we don’t know it as well as we would like or we wouldn’t have autoimmunity to contend with. Well new research reveals new information about how our immune system functions, shedding light on a vital process that determines how the body’s ability to fight infection develops. Which brings us one step closer to the big picture of the immune system.
The team describes a critical mechanism underlying how T cells are created, selected and released into the bloodstream. But let’s rewind a little, first we need some background on the immune system, a T cell is a type of blood cell called a lymphocyte that protects the body from infection. T cell precursors called thymocytes are created in the bone marrow and migrate to the thymus – a walnut-sized organ at the base of the neck – where they turn into T cells.
However, very few thymocytes become fully functional T cells, and in the current study, the team gained important new insights into why.
As they transform into T cells, thymocytes grow receptors that react to an antigen (any substance provoking an immune response) that’s bound to a small molecule called MHC. If this reaction is too strong or too weak, the thymocyte does not mature into a T cell.
The group found that the delicate balance determining the proper reactive ability is controlled by glycosylation, a process in which a sugar attaches to a target protein to give the protein stability and form. They saw that changes in the addition of sugars to receptors – including the blocking of glycosylation – during T cell development profoundly influenced how thymocytes reacted to the MHC-bound antigens and whether they became mature T cells.
Glycosylation also may help explain the creation of self-reactive T cells that escape from the thymus and can go on to attack the body’s own antigens, a process called autoimmunity that’s the basis of immune system disorders such as multiple sclerosis.
“Understanding how T cells are selected for antigen reactivity has been an enigma, and here we have made a major advance in understanding how this selection works,” Dr. Michael Demetriou, lead researcher said.
The work represents a breakthrough in basic research and facilitates further discoveries about T cell processes that could someday yield new therapeutic approaches to infection and autoimmune diseases.
This seemingly small discovery, might help hold the key to fight autoimmunity or even answer other questions or problems we haven’t even come up with yet! It’s a pretty big deal when you think about it.
Zhou RW, Mkhikian H, Grigorian A, Hong A, Chen D, Arakelyan A, & Demetriou M (2014). N-glycosylation bidirectionally extends the boundaries of thymocyte positive selection by decoupling Lck from Ca2+ signaling. Nature immunology PMID: 25263124