Immunobiology researchers from Yale University have identified an antigen that triggers development of Type I diabetes. Though Type 1 diabetes is classified as an autoimmune disease, the agent that stimulates the immune system to attack the pancreas hasn’t been identified until now.
Researchers used NOD (non-obese diabetic) mice for their studies, because mice have a version of Type I diabetes that’s extremely similar to the human version of this disease. For both mice and humans, the major contributing factor for the disease is genetic and involves a defect in an area called the major histocompatibility complex (MHC).
Through an unknown mechanism, the beta cells of the pancreas, which are responsible for making insulin, are attacked by the body as if they are foreign tissue. Defensive cells of the immune system, called CD8 T lymphocytes react to an antigen on the beta cells. The reaction takes the form of an attack, eventually destroying the beta cells, and thereby eliminating the body’s ability to make insulin.
Type I diabetes accounts for approximately 10 percent of all cases of diabetes and usually begins in childhood. Type II diabetes, which is much more common, is not an autoimmune disease but a dysfunction in the metabolism of glucose (sugar). Those with Type I need to take replacement insulin, whereas those with Type II diabetes may or may not need insulin.
While the cells that carry out the destruction had been identified previously, the antigen that sets off the reaction had not. Previous researchers proposed that the offending agent is insulin itself or one of its chemical precursors.
Now that the antigen has been identified, researchers hope to investigate the possibility of using it to desensitize the body, similar to the way allergy shots work. If this can be achieved, it may become possible to prevent Type I diabetes.