Both meningeal (12.5%±1.4%) and parenchymal (12.0%±1.2%) neurosyphilis patients showed pronounced decreases in CD4+CD25high Treg percentage compared to syphilis patients without neurological involvement (P<0.05, P<0.001, respectively) and asymptomatic neurosyphilis patients (P<0.05, P<0.001, respectively) (Table 3). Here, CD4 is linked to syphilis.