Researchers at Columbia University Medical Center and the La Jolla Institute for Allergy and Immunology have discovered the first direct evidence that autoimmunity plays a role in Parkinson's disease. The link to autoimmunity dates back almost 100 years but it had not been confirmed until recent studies.

In particular these researchers have demonstrated that two fragments of alpha-synuclein, a protein that accumulates in the neurons of individuals with Parkinson's disease, can activate the T cells involved in autoimmune attacks. It is still unclear if this immune response causes Parkinson's or is a result of the disease process. Previous researchers had mistakenly presumed that neurons were were protected from autoimmune attacks. However, these newer studies show that dopamine neurons in Parkinson's are vulnerable because they contain protein molecules on the cell surface that may be mistaken as foreign proteins. 

As neurons in Parkinson's are no longer able to break down abnormal alpha-synuclein, autoimmunity arises. Normally, young, healthy cells break down and recycle old or damaged proteins. These studies are important in terms of helping find effective treatment modalities.

In 2002, Italian researchers also demonstrated autoimmunity in individuals with Parkinson's disease when they reported increased levels of both IgM and IgM antiganglioside antibodies in patients with a tremor-dominant form of Parkinson's disease.

 Source:

Columbia University Medical Center. June 21, 2017. Parkinson's is partly an autoimmune disease, Study Finds. Science Daily. 
https://www.sciencedaily.com/releases/2017/06/170621132904.htm