American Board of Surgery Qualifying Exam (ABS QE) Practice Test 2025 - Free Surgery Exam Practice Questions and Study Guide

Sirolimus, also known as rapamycin, is an immunosuppressant that works primarily through the inhibition of the mammalian target of rapamycin (mTOR). One of its significant mechanisms of action is the inhibition of interleukin-2 (IL-2) signaling, which is crucial for T-cell activation and proliferation.

IL-2 is a cytokine that promotes T-cell growth, survival, and differentiation. When Sirolimus inhibits IL-2, it effectively decreases the activation and proliferation of T-cells. This is because T-cells require IL-2 to progress from the G1 phase to the S phase of the cell cycle, promoting their division. Without adequate IL-2 signaling due to Sirolimus's action, T-cell proliferation is significantly diminished, which is particularly beneficial in preventing transplant rejection and managing autoimmune diseases.

This context supports why the correct answer is related to decreased T-cell proliferation, as inhibiting IL-2 directly impacts the body's immune response by reducing the expansion of T-cells that would otherwise be responsive to antigens.