sensibilization

Sensibilization, or sensitization, is the process by which an organism becomes reactive to a stimulus or antigen, often resulting in a heightened response upon subsequent exposures. The term is used across disciplines, including immunology, toxicology, neuroscience, and public health.

In allergy and immunology, sensitization describes the initial encounter with an allergen that leads the immune system to become reactive. For many allergens, this involves the production of antigen-specific IgE antibodies and the priming of mast cells and basophils. On later exposure, the allergen cross-links IgE on these cells, triggering the release of histamine and other mediators and producing symptoms. In contact dermatitis, sensitization is mediated by T cells and can cause a delayed hypersensitivity reaction upon re-exposure.

In toxicology and pharmacology, chemical sensitization occurs when a small dose of a chemical binds to proteins to form hapten-protein conjugates that are recognized by T lymphocytes. Once sensitized, even trace exposures can elicit responses such as dermatitis or asthma. This concept is important for occupational safety and for understanding drug hypersensitivity reactions.

In neuroscience and psychology, sensitization describes an increased response to a stimulus with repeated exposure, such as heightened pain sensitivity or amplified effects of certain drugs. This is distinct from tolerance, where responses diminish with continued exposure.

The term thus covers several contexts: immunological sensitization to allergens, chemical or drug sensitization in toxicology, and neural or behavioral sensitization. Prevention and management typically involve avoidance of triggering agents where possible and appropriate medical care to address symptoms.