Immunsuppression

Immunosuppression refers to a reduction in the activity or effectiveness of the immune system. It can result from disease, medical treatment, or congenital conditions and increases the risk of infections, cancers, and slower wound healing. Immunosuppression may be temporary or long lasting and can affect innate and adaptive immune responses.

Causes and mechanisms vary. They include intrinsic immune deficiencies, acquired conditions such as HIV/AIDS or malnutrition, and iatrogenic suppression from drugs or radiation. Mechanisms include reduced numbers or impaired function of lymphocytes, diminished cytokine signaling, and interference with antigen presentation.

Common iatrogenic causes are pharmacologic immunosuppression used to prevent transplant rejection or treat autoimmune disease. Classes include calcineurin inhibitors (cyclosporine, tacrolimus), mTOR inhibitors (sirolimus), antimetabolites (azathioprine, mycophenolate), and corticosteroids; biologics such as rituximab or anti-TNF agents may also suppress immunity.

Clinically, immunosuppressed patients are at increased risk for bacterial, viral, fungal, and opportunistic infections, as well as certain cancers and slower wound healing. In transplantation, infection and drug toxicity are major concerns, and prophylaxis is commonly used to reduce risk of Pneumocystis jirovecii pneumonia, cytomegalovirus, and herpesviruses.

Management aims to balance disease control with infection risk. This includes individualizing immunosuppressive regimens, monitoring drug levels and adverse effects, providing preventive care and vaccination where appropriate, and promptly treating infections. In some cases, reduction or modification of therapy is necessary.

Diagnosis relies on clinical assessment, laboratory tests (complete blood counts, immunoglobulin levels), and monitoring of drug trough levels when applicable. Imaging and microbiologic testing help identify infections. Prophylaxis and infection control are key components of care.