immunocompromise

Immunocompromise refers to a state in which the immune system has a reduced ability to respond to infections and other challenges. It can be temporary or permanent and may affect innate and adaptive immunity. Individuals with compromised immunity are at greater risk for infections that are more frequent, severe, or prolonged, and they may experience diminished responses to vaccines.

Immunodeficiencies are broadly categorized as primary (congenital) immune disorders and secondary (acquired) immune suppression. Primary immunodeficiencies result from inherited genetic defects affecting components of the immune system, such as antibody production, cell-mediated immunity, phagocytes, or complement pathways. Secondary immunodeficiencies arise from diseases or treatments that suppress immunity, including HIV infection, malnutrition, diabetes, chronic kidney or liver disease, cancer and chemotherapy, organ or bone marrow transplantation with immunosuppressive drugs, corticosteroid use, splenectomy, and aging (immunosenescence).

Mechanisms of immunocompromise include reduced antibody levels, impaired lymphocyte function, defective phagocytosis, impaired barrier defenses, and complement deficiencies. Clinically, these states increase susceptibility to a broad range of infections and can blunt responses to vaccines, with a higher incidence of opportunistic pathogens such as Pneumocystis jirovecii, Candida species, certain bacteria, and reactivation of latent viruses.

Diagnosis is based on clinical history and targeted laboratory testing, including quantitative immunoglobulins, lymphocyte subsets, specific antibody titers, functional assays, and HIV testing. Management focuses on treating the underlying cause when possible, preventing infections through hygiene, vaccines (as appropriate), and antimicrobial prophylaxis, and, in selected cases, immunoglobulin replacement or adjustment of immunosuppressive therapy to balance infection risk with disease control. Prognosis varies with the cause and its reversibility.