immunocompetence

Immunocompetence is the functional capacity of the immune system to mount effective defenses against pathogens and abnormal cells while maintaining tolerance to self tissues and limiting collateral damage. It encompasses both innate and adaptive immunity, their signaling networks, and regulatory mechanisms that shape the magnitude and quality of responses. An immunocompetent system can recognize pathogens, orchestrate inflammation, clear infections, and develop immunological memory through B and T lymphocytes, while avoiding autoimmunity or excessive tissue injury.

Components include innate immunity, providing rapid, nonspecific defense via barriers, phagocytes, dendritic cells, and complement; and adaptive immunity, providing specific responses through B cells generating antibodies and T cells mediating cell-mediated immunity, with regulatory cells restraining responses to prevent damage.

Factors influencing immunocompetence include age, nutrition, genetics, sleep, stress, infections, and environmental exposures. Medications such as immunosuppressants, illnesses like malnutrition or HIV, and cancer therapies can reduce immunocompetence. Immunosenescence refers to the gradual decline in immune function with aging.

Assessment of immunocompetence relies on clinical history (infections and vaccine responses) and laboratory tests such as complete blood count with differential, lymphocyte subset analysis, immunoglobulin levels, antibody titers, and functional assays of lymphocyte proliferation or NK cell activity. Delayed-type hypersensitivity skin tests and measures of immune repertoire can provide additional information.

Clinical relevance: reduced immunocompetence leads to recurrent infections and poor vaccine responses; excessive immunity or dysregulation can contribute to allergies or autoimmunity. Management aims to protect against pathogens and maintain balanced immune function.