This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Medicine
All of the following immunosuppressives cause profound myelosuppression except: 
Select and explain. 
A. Sirolimus, B. Cyclosporine, C. Azathioprine, D. Mercaptopurine
B: Cyclosporine
Answer: B: Cyclosporine 
Explanation: Ciclosporin&;s main effect is to lower the activity of T-cells; it does so by calcineurin-phosphatase pathway.Unlike cytotoxic immunosuppressants, it is free of toxic effects on bone marrow and RE system as it doesn&;t act on cell cycle.(ref: KD Tripathi 6/e p839)