A 45-year-old patient with end-stage renal failure undergoes a living-related renal transplant. Which immunosuppressive drug acts by inhibiting the calcineurin pathway to prevent T-cell activation?

• A Azathioprine
• B Mycophenolate mofetil
• C Cyclosporin ✓
• D Sirolimus (Rapamycin)

Explanation

Cyclosporin and tacrolimus are calcineurin inhibitors that block the phosphatase activity of calcineurin, thereby preventing dephosphorylation of NFAT and subsequent transcription of interleukin-2, which is essential for T-cell proliferation. Azathioprine inhibits purine synthesis. Mycophenolate mofetil selectively inhibits inosine monophosphate dehydrogenase in lymphocytes. Sirolimus (mTOR inhibitor) blocks T-cell proliferation downstream of IL-2 signalling without inhibiting calcineurin.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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