Immunocompetent

Immunocompetent describes an individual whose immune system functions normally, mounting appropriate innate and adaptive immune responses to pathogens. In contrast, immunocompromised refers to impaired immune function due to disease, therapy, or other factors. The term emphasizes a functional state of health rather than a fixed anatomy, and its meaning can be context-dependent.

The immune system comprises innate defenses, such as barriers, phagocytic cells, and complement, and adaptive defenses, including B cells that produce antibodies and T cells that regulate responses and destroy infected cells. Immunocompetence implies the capacity to mount effective responses to infections and to vaccines, as well as to clear pathogens without excessive collateral damage.

Clinical use of the term often serves to distinguish hosts in whom immune deficiency is not suspected from those with primary immunodeficiencies (congenital defects) or secondary immunodeficiencies (acquired conditions such as HIV infection, malnutrition, cancer, or immunosuppressive therapy). It can guide management decisions, such as infection risk assessment and treatment choices.

Immunocompetence is variable and influenced by factors such as age, nutrition, chronic illnesses, and medications. Aging, or immunosenescence, often reduces immune responsiveness, while acute illness or stress can transiently alter function. No single laboratory test universally defines immunocompetence; assessments typically rely on clinical context, vaccination responses, and, when indicated, measurements of immune cell populations and antibody levels.