Basophil –
Main WBC for Allergic Reactions
- Basophils are a type of granulocyte (they have granules in their cytoplasm).
- Their granules are full of histamine, heparin, and other chemicals.
- In an allergic reaction, especially Type I hypersensitivity (like hay fever, hives, anaphylaxis):
- An allergen (like pollen, food, or a drug) causes IgE antibodies to bind to basophils (and mast cells).
- When the allergen binds again, it triggers degranulation → basophils release histamine.
- Histamine causes:
- Vasodilation → redness, warmth
- Increased capillary permeability → swelling (edema)
- Itching, runny nose, watery eyes, bronchoconstriction (in asthma, anaphylaxis)
๐ So basophils are directly responsible for many signs of an allergic reaction because they release histamine.
When the immune system encounters an allergen,
it mistakenly identifies it as a harmful substance.
In response, it produces antibodies called Immunoglobulin E (IgE), which attach to mast cells and basophils.
Upon future exposures, the allergen binds to these IgE antibodies, causing the mast cells to release chemicals like histamine.
This leads to allergy symptoms such as sneezing, itching, swelling, or difficulty breathing.
In severe cases, the reaction can result in anaphylaxis, a life-threatening condition.
