Outline the major types of renal transplant rejection and the common immunosuppressive therapy used.

• A. Hyperacute (antibody-mediated; very rapid), Acute (cell-mediated or antibody-mediated; days–months), Chronic (months–years); immunosuppressants include calcineurin inhibitors, steroids, mycophenolate/azathioprine.
• B. Hyperacute is the only type; no immunosuppression helps.
• C. Rejection cannot be prevented; immunosuppression is useless.
• D. Only acute rejection occurs; chronic rejection is not a concept.

Answer: (A)

Renal transplant rejection comes in three major forms defined by when they occur and how the immune system attacks the graft. Hyperacute rejection happens within minutes to hours after the transplant and is antibody-mediated, driven by preformed donor-specific antibodies (often against HLA or ABO antigens). Because the antibodies are already present, this form causes rapid complement activation and graft vessel thrombosis, leading to immediate graft failure. Prevention hinges on thorough crossmatching before transplantation, and once it occurs, standard maintenance immunosuppression is unlikely to save the graft; therapies that target circulating antibodies (like plasmapheresis and IVIG) and other targeted immune agents are used in management.

Acute rejection arises days to months after transplantation and can be cell-mediated, antibody-mediated, or a combination of both. It responds to treatment aimed at suppressing T cells and reducing antibody effects, with high-dose corticosteroids as the first-line therapy; if needed, more intensive approaches such as lymphocyte-depleting agents (for example, anti-thymocyte globulin) or antibody-directed therapies and plasmapheresis may be employed.

Chronic rejection develops over months to years and reflects ongoing immune injury and chronic allograft vasculopathy, often with progressive fibrosis and graft dysfunction. It is harder to reverse and management focuses on optimizing immunosuppression and controlling risk factors to slow progression, with the goal of maintaining graft function as long as possible.

Common immunosuppressive therapy used to prevent rejection includes a combination approach: calcineurin inhibitors (such as tacrolimus or cyclosporine), corticosteroids, and antiproliferative agents (like mycophenolate mofetil or azathioprine). Some regimens also use induction therapies (e.g., basiliximab) or other agents (such as mTOR inhibitors) in specific situations.