The CSF/serum ratio of CXCL10 in neurosyphilis patients (median 4.13, ranged from 0.07 to 99.9) was significantly higher than that in non-neurosyphilis patients (median 0.4, ranged from 0.06 to 6.08, p = 0.000) (Fig. 2O). Here, CXCL10 is linked to neurosyphilis.