PECAM1 and myeloid sarcoma: Another study showed that the number of CD31 + microparticles of endothelial origin was high in the plasma of MS patients in the exacerbation disease period but not in the remission phase, suggesting that CD31 + microparticles may reflect a chronic injury of the endothelium and represent a marker of acute injury in MS (Minagar et al., 2001).