What is the mechanism behind a photoallergic reaction?
Answer
The immune system identifies a UV-modified chemical as a foreign invader
In a photoallergic reaction, UV light alters the structure of a chemical present in the skin. The body's immune system then mistakenly identifies this new, light-modified compound as a foreign threat. This triggers an immune response that manifests as symptoms like eczema, hives, or rashes. Because this is an immune response rather than direct tissue damage, it often persists longer than phototoxicity and can be triggered by even minimal exposure once the body has been sensitized.
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