Question: In IgE-mediated hypersensitivity reactions: 
 Options:  <1> Eosinophils and mast cells play an important role. <2> There are no cellular elements involved. <3> Antibody-mediated cytotoxicity reactions play a key role. <4> There are no elements of the immune system involved in atopy. <5> The IgE immunoglobulin receptor does not intervene.
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