In light of the hypothesis that altered leptin levels are an explanation for the increased risk of developing MS in obese individuals, we conclude that leptin is a modulating factor that switches the immune system towards a more pro-inflammatory state, by secretion of pro-inflammatory cytokines, upregulation of the leptin receptor, and downregulation of anti-inflammatory Treg cells. The gene discussed is LEPR; the disease is myeloid sarcoma.