Activated caspase-8 in megakaryocytes from a healthy donor and MDS patients. (A) A bone marrow sample from a healthy control. No caspase-8 activity is detected in the megakaryocytes. (B) Bone marrow of an MDS patient showing activated caspase-8 immunonegative megakaryocytes (detected in 5/21 samples, in < 10% of megakaryocytes; indicated by arrowheads). (C) Bone marrow sample of another MDS patient showing a megakaryocyte that is positive for activated caspase-8. Magnification × 400. Slides were observed with an Olympus BX50 microscope (Paes Nederland, Zoeterwoude, The Netherlands) using a 40×/0.75 numerical objective lens. Images were captured with an Olympus DP70 camera (Paes Nederland) and image analysis software (SIS, Münster, Germany). Images were further processed using Adobe Photoshop CS and Illustrator CS (Adobe).