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The science behind allergic reactions
Food allergies, allergies to medications, to dog or cat’s hair, to pollen, to dust… There are reported cases of allergies to so many things, but what is worst is that we sometimes don’t know we are allergic to something until it actually causes us an allergic reaction. Not a very nice situation.

I have talked about the immune system before and how it is there to protect us from potential harmful living or non-living things. I have also talked about the immune system loosing it and causing the development of autoimmune diseases, such as Lupus. Well, allergies also have to do with the immune system, but in this case, it is related to an overreaction of it towards a certain substance.
A normal response
Many mechanisms are used by our immune system to kill the microorganisms that cause damage to our body, such as bacteria, viruses, fungus and parasites, and to particles that enter our body and are not supposed to be there, such as dust.
In a non-allergic person, one of the immune mechanisms that fights against infections is the production of antibodies, which are basically proteins that mark or flag microorganisms in order for the immune cells to recognize them and destroy them as soon as possible. The flagging is possible thanks to the recognition of certain regions of either the microbe or the particle, known as antigen.
After the antigen is identified, the B-lymphocytes activate their production machinery and produce antibodies specific to that antigen. So, each antigen has personalized antibodies, so to speak.
B cells then release the antibodies and these stick to the antigenic region on the microbe, so that immune cells come and finish them off. These cells are known as mast cells.
Inflammatory response
The reaction of mast cells is quite intense.
If you have ever had an inflammatory response, you will remember that the inflammation site gets all swollen, its temperature increases and some pain may be felt, depending on the intensity of the reaction. The good news is that this is a fast and temporary response; it lasts for as long as it takes to get rid of the microbe. After that, the tissue starts regenerating and all the inflammatory signs disappear. There are also medications that help in reducing inflammation, when this is needed.
See Also: Achooooooo: Inside The World Of Seasonal Allergies: A Dozen Tips For Sufferers
During an allergic reaction, the immune system reacts against particles that are not dangerous.
This happens because previously produced antibodies, known as IgE’s, cross-link with these ubiquitous particles, which we can now call allergens, causing the activation of mast cells.
- Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th edition. New York: Garland Science
- 2001. Effector mechanisms in allergic reactions. Available from: www.ncbi.nlm.nih.gov/books/NBK27112/
- Photo courtesy of Tina Franklin by Flickr : www.flickr.com/photos/97481684@N08/13397331035
- Photo courtesy of Eric Skiff by Flickr : www.flickr.com/photos/ericskiff/192877742