Immunologists and epidemiologists know that disease casusing organisms can make proteins that the body assumes belong to it. They use these forged molecular pass keys on the cellular docking ports that allow hormones and other messengers to regulate body activities. It now looks like their deception has another consequence: the body’s messengers can get caught in the friendly fire from the immune system because they look too much like the enemy. In panic about the deceit, the body may instigate an unintended immune attack against itself.
https://www.the-scientist.com/features/do-commensal-microbes-stoke-the-fire-of-autoimmunity–65871