Other phenotypic changes of T cells in PD are also known: reduced absolute lymphocyte counts, decreased absolute and relative counts of total T cells, decreased absolute and relative counts of CD4 + , and sometimes also CD8 + lymphocytes, increased Th1/Th2 and Th17/Treg ratios and increased expression of inflammatory cytokines [5, 12–27]. Here, CD4 is linked to Parkinson disease.