antigensensitized

Antigensensitized refers to a state where an individual's immune system has been exposed to a specific antigen and has developed a heightened response to subsequent exposures. This sensitization process involves the recognition of the antigen by immune cells, primarily lymphocytes. Upon initial contact, the immune system learns to identify the antigen as foreign and triggers a primary immune response. This typically involves the production of antibodies and the activation of T cells.

Following this initial encounter, some of these immune cells, particularly memory B cells and memory T cells, persist in the body. These memory cells are primed to react more rapidly and vigorously upon re-exposure to the same antigen. Therefore, when an antigensensitized individual encounters the antigen again, the secondary immune response is often faster, stronger, and more effective than the primary response. This is the underlying principle behind vaccination, where a weakened or inactivated form of a pathogen (the antigen) is introduced to induce antigensensitization without causing disease, thus protecting against future infections. Conversely, in certain allergic reactions, antigensensitization to a harmless substance can lead to an overactive and detrimental immune response upon subsequent exposure.