Rogue immune cells may contribute to development of PD: here's the link:
http://news.bbc.co.uk/2/hi/health/7795329.stm
I have read now two articles in the past week which implicate immune cells in PD: this article, and the one I posted 12.23.08 which discussed clumps of a specific type of immune cell, the T cell, in the PD brain. Interesting, yes?