immunitet

Immunitet, or immunity, is a term used in different contexts to denote protection or exemption. In biology, it refers to the body's ability to resist infection and disease. In law and political life, it refers to protection from certain legal processes or liabilities. The dual usage reflects distinct concepts that share the idea of safeguarding an entity from harm or consequence.

Biological immunity encompasses two main layers. Innate immunity provides immediate, non-specific defenses such as physical barriers (skin and mucous membranes), phagocytic cells, natural killer cells, the complement system, and inflammatory responses. Adaptive immunity develops after exposure to a pathogen and involves highly specific responses by B lymphocytes (which produce antibodies) and T lymphocytes (which destroy infected cells and regulate immune activity). The adaptive system also exhibits immunological memory, enabling faster and stronger responses upon re-exposure.

Active immunity arises from an infection or vaccination, creating lasting protection in most cases. Passive immunity results from antibodies transferred from another host, offering temporary defense. Vaccination aims to stimulate active immunity without causing disease, contributing to herd immunity when a sufficient portion of the population is protected, reducing transmission and protecting those who are not immune. Duration of protection varies with the pathogen, vaccine, and host factors; some immunity wanes over time or can be circumvented by evolving pathogens or immunodeficiencies.

Legal immunity refers to exemptions from usual legal processes or penalties. This can include diplomatic immunity, parliamentary or certain official immunities, and, in some jurisdictions, functional immunity for specific roles. Immunity may be absolute or limited in scope and can be revoked or waived under particular conditions, such as removal, resignation, or legal reforms.

Immunitet thus describes both a biological defense mechanism and a legal protection, with each domain applying the concept to different forms of safeguard.