CD8A and Parkinson disease: In addition, the study reveals the effect of CD4+ T cells and CD8+ T cells on the pathological development and progression of PD by knocking the mice separately [76], and found that CD4+ T cells exacerbated PD pathological progression by possibly increasing the secretion of pro-inflammatory factors and promoting dopaminergic neuronal toxicity by activating the apoptotic signal Fas- Fas Ligand (FasL) [77].