Using receiver-operating characteristic (ROC) curves, we found that the CD80+:CD19+ ratio and CD19+CD80+ levels could discriminate between patients with impaired mobility in HAM/TSP (p = 0.0010, AUC = 0.96) and patients with active MS (p = 0.0077, AUC = 0.88), respectively. The gene discussed is CD80; the disease is myeloid sarcoma.