Type I hypersensitivities require which of the following initial priming events to occur?

• A. Activation of cytotoxic T cells
• B. Release of histamine from basophils
• C. Production of IgG antibodies
• D. Sensitization of mast cells by IgE antibodies

Answer: (D)

Verified step by step guidance

1. Understand that Type I hypersensitivity is an allergic reaction that occurs rapidly upon exposure to an allergen.
2. Recognize that the initial priming event involves the immune system's response to the first exposure to the allergen.
3. Learn that during this first exposure, B cells produce IgE antibodies specific to the allergen.
4. These IgE antibodies bind to receptors on the surface of mast cells, a process known as sensitization.
5. Upon subsequent exposure to the same allergen, these sensitized mast cells release histamine and other mediators, leading to the symptoms of an allergic reaction.