Immunosuppression

Immunosuppression refers to reduced activity of the immune system, impairing the body's ability to fight infections and respond to diseases. It can be intentional, as a therapeutic goal in conditions such as organ transplantation and autoimmune diseases, or it can arise secondarily from infections, malnutrition, aging, cancer, or medical treatments. Primary immunodeficiencies are genetic disorders, while secondary (acquired) immunodeficiencies result from other conditions or therapies.

Mechanisms of immunosuppression involve dampening both cellular and humoral immune responses. T cell–mediated immunity is commonly targeted to prevent graft rejection or to control autoimmune activity, and B cell function or antibody production may be reduced as well. Innate immune responses can also be affected, and overall immune surveillance against opportunistic pathogens and malignancies is diminished.

Pharmacologic immunosuppressants are a central tool in medicine. Corticosteroids (e.g., prednisone) broadly suppress immune activity. Calcineurin inhibitors (cyclosporine, tacrolimus) reduce T cell activation. Antimetabolites (azathioprine, mycophenolate mofetil) interfere with lymphocyte proliferation. mTOR inhibitors (sirolimus) and alkylating agents provide additional mechanisms of suppression. Biologics and monoclonal antibodies (e.g., rituximab, abatacept) selectively target immune pathways. Dosing and monitoring are tailored to the patient’s condition, with attention to drug interactions and organ function.

Health risks include increased susceptibility to bacterial, viral, fungal infections and opportunistic organisms, and a higher risk of certain malignancies. Metabolic effects, hypertension, osteoporosis, and delayed wound healing may occur. Vaccination responses can be blunted, and live vaccines are often avoided in substantial immunosuppression.

Management emphasizes balancing disease control with infection risk. This includes infection prophylaxis when indicated, regular monitoring of immune and organ function, vaccination planning, and coordinated care among specialists.