Among syphilis individuals with neurological involvement, there was no significant difference in CD4+ CD25high Treg frequency (P>0.05) (Figure 3C) and CD4+ Foxp3+ Treg frequency (P>0.05) (Figure 3D) in peripheral blood among asymptomatic, meningeal, and parenchymal neurosyphilis patients. Here, FOXP3 is linked to neurosyphilis.