The immune system remembers. Often this memory, primed by past encounters with threats like bacteria or viruses, is an asset. But when that memory is sparked by internal drivers, like chronic inflammation, it can prove detrimental, perpetuating a misguided immune response. In a new paper, researchers demonstrated that recipients of a bone marrow transplant were predisposed to more severe arthritis if their donor had inflammatory gum disease. The researchers note that this mechanism may also prompt a reconsideration of how bone marrow donors are selected. …To put the whole picture together regarding the link between inflammatory conditions, the "critical experiment,"...