What causes allergies?

Allergies are specifically caused by the immune system's inappropriate response to harmless substances, known as allergens. When these allergens, such as pollen, pet dander, or certain foods, enter the body, the immune system mistakenly identifies them as threats. In response, the immune system produces specific antibodies called Immunoglobulin E (IgE). These antibodies attach to mast cells and basophils, which are types of white blood cells that release histamine and other chemicals. These substances lead to the symptoms commonly associated with allergies, such as sneezing, itching, and swelling.

The process of generating antibodies for non-threatening substances underscores the role of allergies in the immune response. Instead of defending against a genuine threat, the body reacts to benign materials, illustrating a fundamental misunderstanding by the immune system.

Other options speak to different aspects of immune function. For instance, infections in the immune system can lead to other responses or conditions but are not directly responsible for allergic reactions. Similarly, errors in T-cell responses may contribute to other immune dysfunctions or autoimmunity but do not specifically account for the allergic reaction pathway. Lastly, exposure to pathogens relates to the immune response against infectious agents rather than the misconceptions causing allergies.