Cyclosporine, an immunosuppressive drug, given to avoid transplant rejection acts by
Cyclosporine, an immunosuppressive drug, given to avoid transplant rejection acts by
Select an option to attempt
Correct Answer: Option C
Explanation
Cyclosporine A (CsA) mechanism of immunosuppression: CsA binds to cyclophilin (CypA, a cytoplasmic immunophilin/peptidyl-prolyl isomerase). The CsA-cyclophilin complex inhibits calcineurin (protein phosphatase 2B, PP2B), a calcium/calmodulin-dependent phosphatase. Calcineurin normally dephosphorylates NFAT (Nuclear Factor of Activated T cells), allowing it to translocate to the nucleus and activate IL-2 transcription. By blocking calcineurin → NFAT remains phosphorylated (cytoplasmic) → IL-2 not produced → T cells cannot proliferate (T cell activation suppressed). Tacrolimus (FK506) has the same mechanism but binds FKBP12 instead of cyclophilin. CsA is used to prevent allograft rejection and treat autoimmune diseases.