FAS and myeloid sarcoma: The T-cell CD95/Fas function is dysregulated in the MS patient with increases in soluble CD95 in relapsing remitting MS and elevated CD95L expression in inflammatory infiltrates in both active and chronic lesions.54, 55 It may be that modulation of CD95 is just representative of activation, or possibly suppression through apoptosis, as previously suggested.23 The biological plausibility of this association is not a leap as one hallmark of acute infectious mononucleosis is enhanced CD95 and CD95L expression.52, 56