Immunosuppressant medications, also known as immunosuppressive agents, are a class of drugs
that suppress or weaken the body's immune system. These medications play a crucial role in
various medical conditions, including organ transplantation, autoimmune diseases, and certain
inflammatory disorders. By modulating the immune response, immunosuppressants prevent the
body from rejecting transplanted organs or tissues and alleviate the symptoms of autoimmune
diseases, where the immune system mistakenly attacks healthy cells.
Mechanisms of Action
Immunosuppressants work through various mechanisms to dampen the immune response. Some
drugs target specific components of the immune system, such as T cells or B cells, while others
interfere with the production of cytokines, signaling molecules that mediate immune responses.
The following are some key mechanisms of action of immunosuppressant medications:
Inhibition of Calcineurin: Calcineurin inhibitors, such as cyclosporine and tacrolimus,
block the activity of calcineurin, an enzyme essential for T cell activation. By inhibiting
calcineurin, these drugs prevent the production of cytokines, such as interleukin-2 (IL-2),
which are crucial for T cell proliferation and activation.
Inhibition of mTOR: mTOR inhibitors, such as sirolimus and everolimus, block the
mammalian target of rapamycin (mTOR), a protein kinase that plays a key role in cell
growth and proliferation. By inhibiting mTOR, these drugs suppress T cell and B cell
proliferation, as well as cytokine production.
Antimetabolites: Antimetabolites, such as azathioprine and mycophenolate mofetil,
interfere with DNA synthesis and cell proliferation. These drugs primarily affect rapidly
dividing cells, such as lymphocytes, which are key components of the immune system.
Corticosteroids: Corticosteroids, such as prednisone and methylprednisolone, are potent
anti-inflammatory and immunosuppressive agents. They work by inhibiting the
production of inflammatory cytokines and suppressing the activity of various immune
cells.