The B-cells have not been observed yet in the brains of patients with PD patient; however, immunoglobulin G (IgG), but not IgM, is deposited in the SNpc on dopaminergic neurons in postmortem brains of patients with PD, colocalizing with α-syn aggregates (Orr et al., 2005). This evidence concerns the gene CD40LG and Parkinson disease.