Allergies are caused by an overreaction of our immune system. A normally harmless substance - like pollen, food or cat saliva - will cause the immune system to defend the body against it.

Components of an allergic reaction

In order to understand how allergies work we need to know the three key players that cause an allergic reaction.

  1. An allergen (antigenic protein) from pollen, food (e.g. nut or shellfish), animal or house dust mite.
  2. An antibody protein known as the Immunoglobulin E, or IgE for short.
  3. A cell referred to as a mast cell.

Allergic reaction

Now let us take a look at how these players cause an allergic reaction.


If you are allergic to pollen, your body will produce a large amount of allergen-specific IgE antibodies when you come in contact with pollen.


The IgE antibodies bind to mast cells. The allergen cross-links them. This triggers the mast cells to release powerful chemicals like histamines.


Histamines cause the allergic symptoms like itching and runny nose.

  • Wild-type allergen
  • IgE antibody
  • Receptor  

Histamine causes the allergic symptoms like itching, wheezing and a runny nose. Histamine, however, is not the reason for an allergy; just the end product. The allergy is caused by allergen-specific IgE antibodies that recognize the allergen and trigger the release of histamine from the mast cells.

Allergies are treated in three different ways. The most common treatment is avoiding the allergen altogether. The second option is medication. Drugs like antihistamines treat the allergic symptoms, but not the allergy itself. The third treatment option is immunotherapy that affects the actual allergic condition by helping the body produce less IgE and build long-term tolerance to the allergen.

Read on about how Desentum treats allergies »