Overview

Immunosuppression denotes a reduction in the activity or effectiveness of the immune system. It may be induced deliberately as part of medical treatment or occur as a consequence of disease, therapy, or genetic conditions. Intentional immunosuppression is a cornerstone of organ transplantation and of therapy for many autoimmune and inflammatory disorders, while unintended immunosuppression raises the risk of infection and other complications. For a brief definition see immune system activity.

Mechanisms and types

Approaches to lowering immune function vary from broad, nonselective inhibition to targeted modulation of specific cells or signaling pathways. Systemic agents blunt many immune responses, whereas newer biological therapies target precise molecules such as cytokines or lymphocyte subsets. Physical interventions such as radiation and some chemotherapies also suppress immune cells.

Common causes and therapeutic uses

Immunosuppressive strategies are used to prevent rejection after organ or bone marrow transplantation and to control autoimmune diseases that attack healthy tissue, for example rheumatoid arthritis and multiple sclerosis. Typical drug classes include corticosteroids (synthetic analogs of cortisol), calcineurin inhibitors, antiproliferative agents, mTOR inhibitors, and biologic monoclonal antibodies.

Risks and monitoring

  • Increased susceptibility to common and opportunistic infections.
  • Higher long-term risk of certain cancers and reactivation of latent infections (e.g., tuberculosis, herpes viruses).
  • Drug-specific toxicities such as metabolic changes, bone loss, or organ toxicity.

Clinical management emphasizes dosing balance, laboratory monitoring, prophylaxis against common pathogens, vaccination planning, and periodic reassessment of the need for continued suppression.

Distinctions and notable facts

Immunosuppression differs from primary immunodeficiency (inborn defects) and from immunomodulation (which may increase or decrease immunity). The development of targeted biologics has allowed more specific suppression with fewer systemic effects, but no therapy is without trade-offs. Careful individualized management seeks to control harmful immune responses while minimizing adverse consequences.