Pearson correlation analysis showed that there was a positive correlation between the percentage of circulating CD4+ CD25high Tregs and serum RPR titer in secondary syphilis (r = 0.27, P<0.01, Figure 2B), latent syphilis (r = 0.27, P<0.05, Figure 2C) and serofast (r = 0.44, P<0.01, Figure 2D) syphilis patients, but no correlation in primary syphilis patients (r = 0.10, P = 0.44, Figure 2A). This evidence concerns the gene CD4 and syphilis.