__________ are hypersensitivity disorders of the immune system.

__________ are hypersensitivity disorders of the immune system.

• A. Allergies
• B. Infections
• C. Autoimmune diseases
• D. Immunodeficiencies

Answer: (A)

Hypersensitivity reactions are immune responses that overreact to harmless substances. Allergies are a classic example, where exposure to things like pollen, certain foods, or pet dander triggers an exaggerated immune response. In many allergic reactions, the body makes IgE antibodies that coat mast cells and basophils; when the allergen re-enters, it cross-links those IgE molecules, causing mast cell degranulation and release of histamine and other mediators. This leads to symptoms such as itching, runny nose, sneezing, hives, wheezing, or even anaphylaxis in severe cases. There are other types of hypersensitivity, but allergic reactions primarily involve type I mechanisms and related pathways. By contrast, infections involve pathogen-driven disease, autoimmune diseases involve immune attacks on the body’s own tissues, and immunodeficiencies reflect a weakened ability to mount an immune response.

Hypersensitivity reactions are immune responses that overreact to harmless substances. Allergies are a classic example, where exposure to things like pollen, certain foods, or pet dander triggers an exaggerated immune response. In many allergic reactions, the body makes IgE antibodies that coat mast cells and basophils; when the allergen re-enters, it cross-links those IgE molecules, causing mast cell degranulation and release of histamine and other mediators. This leads to symptoms such as itching, runny nose, sneezing, hives, wheezing, or even anaphylaxis in severe cases. There are other types of hypersensitivity, but allergic reactions primarily involve type I mechanisms and related pathways. By contrast, infections involve pathogen-driven disease, autoimmune diseases involve immune attacks on the body’s own tissues, and immunodeficiencies reflect a weakened ability to mount an immune response.