In vitro culture of monocytes from MS patients with MP resulted in an increased gene expression of the M2 markers ARG1, CD163, and CD206 and the anti-inflammatory cytokine IL10, and the concomitant down-regulation of the mRNA level of the pro-inflammatory cytokine IL1B. This effect was even more pronounced after MS patients were subjected to 24 h of MP pulse therapy. The gene discussed is CD163; the disease is myeloid sarcoma.