Findings that macrophages and microglia are some of the main p75NTR-expressing cells in multiple sclerosis (MS) lesions (Dowling et al., 1999), together with evidence that NGF/p75 activation can limit the microglia’s inflammatory cascade (Neumann et al., 1998), also seem to implicate NGF signaling in neurotrophin-mediated immune modulation at MS lesion sites. The gene discussed is NGF; the disease is myeloid sarcoma.