EPX and myeloid sarcoma: The activity of eosinophils assessed with eosinophil peroxidase (EPO) activity was increased in MS vs. NH females (17.86 (16.2–24.6) vs. 4.4 (2.4–7.5) μg EPO/g of tissue; p < 0.01; n = 7–8; Figure 2B).