Your roommate is rushed to the hospital after suffering a...

Your roommate is rushed to the hospital after suffering a severe allergic reaction to a bee sting. After she is treated and released, she asks you (the local biology expert!) to explain what happened. She says, "I don't understand how this could have happened. l've been stung by bees before and didn't have a reaction." Suggest an explanation for what has happened to cause her severe allergic reaction and why she did not have the reaction after previous bee stings.

Key Concepts

Sensitization

Sensitization refers to the process by which the immune system becomes primed to recognize and respond to a specific antigen after an initial exposure. In cases of allergy, a previous exposure to an allergen such as bee venom leads the body to produce specific antibodies, which is why subsequent exposures can trigger a stronger reaction.

IgE-Mediated Hypersensitivity

IgE-mediated hypersensitivity is a type of allergic reaction where the immune system produces IgE antibodies specific to an allergen. These antibodies bind to mast cells and basophils, setting the stage for an immediate and severe allergic response upon re-exposure to the allergen.

Mast Cell Activation

Mast cell activation is a key aspect of IgE-mediated allergic reactions. When the allergen binds to the IgE antibodies on the surface of mast cells, it triggers these cells to release histamine and other inflammatory mediators responsible for the symptoms of an allergic reaction.

Secondary Immune Response

The secondary immune response is the body's enhanced reaction to an antigen that it has encountered before. Because memory cells remain after the initial exposure, subsequent encounters with the allergen result in a quicker and more vigorous immune response, which in the case of allergies, can lead to severe symptoms.

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