CD2 and Parkinson disease: Of interest, PD and AP patients expressed higher amounts of HLA-I, CD8, CD2, CD3, CD14 and CD20 in CSF, while no or very low detection was observed in HC, suggesting a CNS activation of the immune system, in particular of the T cell-mediated immunity with particular emphasis on intracellular endogenous synthetized antigens that involves the activation of HLA class I [37,38] and are presented to CD8 T cells [39].