An antirejection regimen typically includes which classes of drugs?

• A. Steroid
• B. Calcineurin inhibitor; Antimetabolite; Steroid
• C. Monoclonal antibody only
• D. Calcineurin inhibitor only

Answer: (B)

Maintaining a transplanted organ relies on suppressing the T-cell–driven immune response through a multi-pronged approach. A typical maintenance regimen combines a calcineurin inhibitor, an antimetabolite, and a corticosteroid. The calcineurin inhibitor (such as tacrolimus or cyclosporine) blocks the signal that activates T cells by preventing IL-2 transcription, which reduces T-cell activation. The antimetabolite (like mycophenolate mofetil or azathioprine) inhibits lymphocyte proliferation by interfering with purine synthesis, limiting the expansion of both T and B cells. The corticosteroid (prednisone or methylprednisolone) provides broad anti-inflammatory effects, dampening multiple immune pathways and helping prevent early rejection.

Using only a steroid lacks sustained, targeted control of T-cell activation; using a monoclonal antibody alone is generally reserved for induction therapy or treatment of rejection rather than maintenance; and using a calcineurin inhibitor alone misses the antiproliferative and broad anti-inflammatory actions needed for robust, multi-pathway immunosuppression.