Consistently with CD25 expression, the highest percentage of Foxp3+ Tregs among CD4+ T cells were observed in patients with secondary syphilis (4.3%±0.4%, p<0.001) and serofast syphilis (4.3%±0.3%, p<0.001) patients, followed by latent syphilis (3.9%±0.4%, p<0.01) and primary syphilis patients (3.6%±0.4%, p<0.05), which were all significantly higher than healthy donors (2.3%±0.1%) (Figure 1B). Here, CD4 is linked to syphilis.