An adult patient with a chronic myelogenous leukemia sits down with you to discuss his questions and concerns about his upcoming bone marrow transplant. He has already received some educational materials and participated in a family conference during which health team members described the procedure and potential complications. He has been told that he has a risk of graft rejection or graft versus host disease (GVHD), but he does not understand the distinction (Chapter 12, Learning Objectives 1, 2, 10, 11).

1. What are the similarities between graft versus host disease and graft rejection?
2. What are the pathophysiologic differences between graft versus host disease and graft rejection?
3. How would these differences be manifested clinically?
4. Studies have shown a protective effect of mild to moderate GVHD in cancer patients who have had a bone marrow transplant. Based on your understanding, can you explain these findings?