Since previous work has shown that EMMPRIN expression is elevated on cells in active perivascular inflammatory cuffs in autopsied MS specimens, the lack of elevation of sEMMPRIN in the CSF during presumed active disease indicates that either membrane associated EMMPRIN in active MS brain lesions is not correlated with the cleaved sEMMPRIN form, or that sEMMPRIN drained into the CSF from active lesions is not detectable over the high levels already constitutive to the CSF compartment. The gene discussed is BSG; the disease is myeloid sarcoma.