Immunosuppressants Used in Kidney Transplantation

Immunosuppressants are critical in preventing rejection of transplanted organs, particularly kidneys.
They act by inhibiting the immune response, specifically targeting T cells and other aspects of lymphocyte function.

Basiliximab: A monoclonal antibody that targets CD25 on activated T cells, blocking the IL-2 receptor; this action inhibits T cell proliferation.
Daclizumab: Similar to basiliximab, it targets the IL-2 receptor by binding to CD25 and thereby suppressing T cell activation.
General Note: Both agents can be identified by their suffix "-ab," indicating monoclonal antibodies.

These agents interfere with the synthesis of nucleic acids, impacting the replication of lymphocytes.
- Azathioprine: A purine analog that disrupts DNA synthesis in lymphocytes, leading to reduced proliferation and activation.
- Cyclophosphamide: An alkylating agent that alkylates DNA, causing cross-links and preventing cell division.
- Mycophenolate: Inhibits inosine monophosphate dehydrogenase (IMPDH), crucial in purine synthesis, thereby selectively targeting lymphocytes over other cell types.
- Sirolimus: A kinase inhibitor that interferes with the mTOR pathway, inhibiting cell cycle progression in T cells and B cells, essentially blocking their activation and proliferation.

Critical in disrupting T cell activation and function through inhibition of specific signaling pathways.
- Cyclosporine: Inhibits calcineurin, preventing the dephosphorylation of NFAT transcription factors necessary for IL-2 production by T cells, thereby blocking T cell activation.
- Tacrolimus: Similar to cyclosporine but with a different binding mechanism; it also inhibits calcineurin, leading to reduced IL-2 transcription and T cell activation.

Potent anti-inflammatory agents that have immunosuppressive effects as well.
- Prednisone: A synthetic corticosteroid that has anti-inflammatory and immunosuppressive properties; it suppresses the immune response by inhibiting various signaling pathways in immune cells.
- Methylprednisolone: Similar to prednisone, it reduces inflammation and immune activity, specifically blocking histamine release and attenuating the functions of phagocytes and lymphocytes.

T Cell Attack: Primary target is the T cells or T cell receptors, directly inhibiting their proliferation or function.
Inhibition of Lymphocyte Replication: Achieved through antimetabolites and cytotoxic agents which block DNA synthesis.
Disruption of T Cell Function: Achieved through calcineurin inhibitors affecting critical signaling pathways like IL-2 production.
Anti-inflammatory Effects: Glucocorticoids like prednisone and methylprednisolone play a vital role in suppressing immune response and inflammation, essential post-transplantation to prevent rejection.