CD4 and myeloid sarcoma: As for the changes induced by PP in MS patients, the markers that have been evaluated belong to the immune system, and hence PP, restores the responsiveness to IFN therapy [19,20], normalizes lymphocyte CD4 counts, CD8, HLADR antigen-bearing cells, NK, serum IFN, and the monocyte/macrophage cell population in PP responders [19].