CXCL13 and neurosyphilis: In patients with ocular syphilis and neurosyphilis the AH/serum ratio for CXCL13, CXCL10 and CXCL8 was 3.78, 89.72 and 24.92 respectively while in patients with ocular syphilis without neurosyphilis the AH/serum ratio for CXCL13, CXCL10 and CXCL8 was 2.82, 76.89 and 14.04 respectively.