immediate allergy


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im·me·di·ate hy·per·sen·si·tiv·i·ty

an exaggerated immune response mediated by mast cell-bound IgE antibodies occurring within minutes after exposing a sensitized individual to the approximate antigen; also called Type I hypersensitivity. Clinical symptoms result from the physiologic effects of preformed or newly generated mediators, including histamine, platelet activating factor, prostaglandins, leukotrienes, bradykinin, tachykinins, and others. The reaction may be localized to specific organ systems or be generalized, leading to anaphylaxis. Symptoms include pruritus, urticaria, angioedema, conjunctivitis, sneezing, rhinorrhea, bronchospasm, hypotension, arrhythmias, and shock. See: allergy.

im·me·di·ate al·ler·gy

(i-mē'dē-ăt al'ĕr-jē)
A type I allergic reaction; so called because in a sensitized subject the reaction becomes evident usually within minutes after contact with the allergen (antigen), reaches its peak within an hour or so, then rapidly recedes.
See also: immediate reaction, anaphylaxis
Compare: delayed allergy