Several immune modulators, such as microglial cells and dopaminergic neuron expressions of CD1d, MHC I, and MHC II molecules, as well as increased brain infiltration of T cell subsets, including CD4+ T cells, CD8+ T cells, and NKT cells, and higher production of proinflammatory cytokines, have been observed in mouse models and human patients with PD [320,321,322,323,324]. Here, CD8A is linked to Parkinson disease.