Ortler et al. demonstrated for the first time that B7-H1 was highly expressed in the inflammatory areas of white matter in MS patients and was likely to be expressed on activated microglia/macrophage, which was consistent with the hypothesis that B7-H1 expression may reduce T cell activation and promote immune homeostasis in the CNS (Ortler et al., 2008). This evidence concerns the gene CD274 and myeloid sarcoma.