We first compared concentrations of selected chemokines in the sera of patients in MS relapse with their concentrations in the sera of control subjects, and detected significantly lower concentrations of CXCL10 and CXCL8 in RRMS patients (CXCL10, 76.49 [40.17–128.90] pg/mL; CXCL8, 50.16 [34.25–86.61] pg/mL) in comparison to controls (CXCL10, 171.40 [138.31–249.79] pg/mL; CXCL8, 64.02 [47.05–242.34] pg/mL; p < 0.001; p = 0.026, respectively, Mann–Whitney test, Figure 1A,B). The gene discussed is CXCL10; the disease is myeloid sarcoma.