Which mediator is primarily responsible for initiating the urticaric response?

The primary mediator responsible for initiating the urticaric response is IgE, or immunoglobulin E. Urticaria, commonly known as hives, is an allergic reaction that manifests as raised, itchy welts on the skin. The mechanism begins with the sensitization phase where, upon first exposure to an allergen, IgE antibodies are produced. These antibodies bind to mast cells and basophils, priming them for future exposure.

When a subsequent exposure to the same allergen occurs, the allergen cross-links the IgE antibodies on these immune cells, leading to degranulation. This degranulation releases a variety of inflammatory mediators, including histamine, which causes the classic symptoms of urticaria such as redness, swelling, and itching. Thus, the role of IgE is crucial as it initiates the process that ultimately results in the development of urticaria.

Other mediators like cyclic AMP and prostaglandins play roles in different physiological processes, such as signaling pathways and inflammation, but they do not primarily initiate the urticaric response. Similarly, prednisone is a corticosteroid that may be used to treat inflammation but does not directly trigger the urticaric response. Therefore, IgE