Transplant Immunosuppression: Calcineurin Inhibitors – Cyclosporine and Tacrolimus

Cyclosporine and tacrolimus are calcineurin inhibitors. After a T lymphocyte recognises foreign graft tissue, calcineurin normally enables transcription of interleukin-2, a signal that supports T-cell activation and expansion. Blocking calcineurin reduces interleukin-2 transcription, dampens the cellular immune response, and lowers the chance of graft rejection. That same immune suppression creates the central trade-off: the graft is protected, but the patient is less able to control infection and abnormal lymphocyte proliferation. These drugs are used to prevent rejection and manage acute rejection in transplantation, including adult kidney, liver, heart, and bone-marrow transplantation. In Canada, cyclosporine also has approved use for severe psoriasis, and tacrolimus has an approved use for rheumatoid arthritis. A kidney-transplant recipient with a new creatinine rise illustrates why the mechanism alone is not enough. The change may reflect calcineurin-inhibitor nephrotoxicity, rejection, dehydration, infection, obstruction, or an interacting medication that has raised the drug concentration. The nurse should treat the creatinine rise as a signal requiring rapid assessment—not as proof of rejection or proof of toxicity.