 Border-associated macrophages are a specialized type of macrophage located at the border between neurons and glia in the brain. They have been implicated in the pathology of Parkinson's disease, but their exact role in the progression of the disease was not known. This study shows that these macrophages are critical in the initiation of the inflammatory response caused by alpha-cynecline, which is a hallmark of Parkinson's disease. The researchers also showed that these macrophages are responsible for activating T-cells, which are important in the body's immune response. By understanding how these macrophages contribute to the progression of Parkinson's disease, it may be possible to develop new treatments to slow or stop the disease from progressing. This article was authored by A. M. Schoenhoef, D. A. Fig, G. P. Williams, and others.