As shown in Figure 3A and 3B, syphilis patients with neurological involvement (including both asymptomatic and symptomatic syphilis patients) had higher percentage of CD4+ CD25high Tregs (4.7%±0.2%, P<0.001) and CD4+ Foxp3+ Tregs (5.0%±0.4%, P<0.001) in peripheral blood compared with healthy individuals (2.7%±0.1% and 2.4%±0.1%, respectively). Here, CD4 is linked to syphilis.