The mechanism of action of cyclosporine involves its ability to suppress the immune system’s response, particularly by targeting T lymphocytes (T cells), which play a crucial role in immune reactions.
The primary target of cyclosporine is calcineurin, a protein phosphatase found in T cells. When T cells are activated, calcineurin plays a role in signaling pathways that produce and release cytokine molecules involved in immune responses. cyclosporine binds to a protein called cyclophilin, forming a complex that inhibits calcineurin’s activity.
This prevents the activation of transcription factors called a nuclear factor of activated T cells (NFAT), which are necessary to produce cytokines such as interleukin-2 (IL-2). As a result, the immune response is suppressed, reducing the activity of T cells and the overall immune response.
The spectrum of activity of cyclosporine is mainly focused on T cells, although it may also affect other immune cells to some extent. By suppressing T-cell activation and cytokine production, cyclosporine helps prevent the rejection of transplanted organs by dampening the immune response against the foreign tissue.