On the basis of these findings, it is suggested that microglial cells and dopaminergic-neuron-mediated cellular take-up of lipids, (e.g., TAG, GPE, PA, PE, PC, GM1, GM2, and GM3) and/or such lipid-induced alteration in pathogenic forms of α-syn (Figure 1), as well as their cellular processing and presentation by CD1d to NKT cells (for lipids) or presentation and delivery through MHC I/MHC II (for lipid-induced activated forms of α-syn) to corresponding T cell subsets (e.g., CD4+ and CD8+ T cells) cause massive generation of proinflammatory cytokines, which is lethal in PD. This evidence concerns the gene CD4 and Parkinson disease.