25668
Allergy is an acquired hypersensitivity reaction of the immune system mediated by cross - linking of the allergen - specific IgE - bound high - affinity IgE receptors , leading to immediate mast cell degranulation .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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