TNF and myeloid sarcoma: As it was shown that TNF-TNFR1 signaling induces TNFR2 shedding (Higuchi and Aggarwal, 1994), the increase in TNFR2 expression in microglia/macrophages in the MS brain could be part of a homeostatic response regulating TNF activity, as previously shown for regulatory T cells (van Mierlo et al., 2008).