Organ Transplants and Immunosuppression

Replacement of diseased tissues or organs by healthy ones is called transplantation.

• The Rejection Problem: When foreign tissue is transplanted, the recipient's immune system recognises it as an antigen and stimulates an immune response to reject it.
• Allograft: A transplant using tissue from another person (e.g., skin from a donor). This is usually rejected by the body.
• Autograft: A transplant using tissue from the patient's own body (e.g., using thigh skin to treat a burn on the forehead). This is never rejected because the immune system does not develop mechanisms against 'self' tissues.

• Tissue Matching: A mandatory pre-transplant procedure to ensure the donor organ is compatible with the recipient.
• X-irradiation: Exposing the patient's bone marrow and lymph tissues to X-rays to inhibit blood cell production, which slows down the rejection process.
• Immunosuppressant Drugs: Medications such as cortisol and cyclosporine are heavily used to suppress the immune system and prevent it from attacking the new organ.

• The required drugs are highly expensive.
• By suppressing the entire immune system, patients become highly vulnerable to other infections.
• Prolonged immunosuppression can make patients more prone to developing cancer.

• To overcome the dangers of non-specific immunosuppression, scientists are looking for ways to suppress only the specific immune response (T-cell response) targeting the new graft, leaving the rest of the immune system functioning normally.
• The Most Promising Method: Treating the patient or their bone marrow with specific antibodies designed to recognise and destroy only the exact T-lymphocytes responsible for graft rejection.

• Transplantation involves replacing diseased organs, but foreign tissues are typically recognised as antigens and rejected by the recipient's immune system.
• Rejection does not occur if the transplanted tissue is taken from the patient's own body, as the immune system naturally accepts its own cells.
• To prevent foreign organ rejection, medical procedures rely on careful tissue matching, X-irradiation, and immunosuppressive medications such as cortisol and cyclosporine.
• Current immunosuppressive treatments suppress the entire immune system, which is not only expensive but also leaves patients highly vulnerable to infections and cancer.
• A promising future solution involves using specialised antibodies to destroy only the specific immune cells causing rejection, allowing the rest of the immune system to function safely and normally.