In this task, you are given a question and answer options for that question. Using this information, you have to classify each text into different topics: medicine, nursery, psychology, chemistry, pharmacology, biology.
Q: Question: In IgE-mediated hypersensitivity reactions:
Options: <0> Eosinophils and mast cells play an important role. <1> There are no cellular elements involved. <2> Antibody-mediated cytotoxicity reactions play a key role. <3> There are no elements of the immune system involved in atopy. <4> The IgE immunoglobulin receptor does not intervene.
A:
medicine