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Allergies: An Overactive Immune System

by — 2014-07-30 in Allergies
Allergies are a very common medical problem. Many people around the world is allergic to either food, pollen, medications and even certain substances present in everyday products. But how do we develop an allergy? The blame falls onto the immune system.

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. 

Sometimes, the immune system overreacts to any of this and causes an exaggerated defense response that instead of helping us to get rid of the hazard, it can severely damage our tissues and even cause death.

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.

They release substances that promote inflammation, which is an attack strategy from the immune system towards the infectious agent that involves the attraction of more immune cells to the infection site, the increase in the release of killing substances and the initiation of the healing process.

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.

Inside An Allergic Reaction

Let me explain this with an example. I am sure you know at least someone that is allergic to seafood. Why does seafood allergy happen?

From a simple rash to anaphylactic shock

When someone allergic to seafood accidentally eats a shrimp, it will reach the gut and previously preformed IgE’s will attach to whatever region they recognize on any of the shrimp components, whether it’s a protein or a substance. This action starts the activation of mast cells, which release pro-inflammatory agents that induce the immune response.

The reaction can be very mild, just a simple rash on the skin. It can also be very intense though: the patient can experience a skin rash, followed by inflammation of the mucosa (lips, eyelids, tongue) and the eventual inflammation of the trachea. This last effect can eventually lead to the closing of the respiratory tract and breathing difficulties.

These last response is known as anaphylactic shock, which is the medical term for an extremely intense allergic reactions. These can be seen mainly when the patient is allergic to medications, for example, or to inimaginable things, such as the stain of a bee or certain substances present in nuts. 

Who would know that all this could happen in a matter of seconds? The immune response is very very fast. It is supposed to be, but in the case of allergic reactions this is not a good thing, because it means that, if the reaction is too intense, it can cause death in no time.

Is there a reason for developing allergies?

Why do we develop allergies? When we are exposed to the allergens for prolonged periods of time, we can develop an allergy. It is very common to develop certain allergies later in life. Allergies to medications, for example, can be presented after a chronic consumption of the drugs, specially when it comes to antibiotics.

The most common antibiotic allergy is to penicillin, but there can be several.

Allergic reactions vary depending on the type of allergen. For example, rhinitis an asthma are both allergic reactions caused by inhaled allergens; skin allergies can manifest as eczema, urticaria, or even the formation of ampules. Food allergies are mainly associated with gut related symptoms, such as diarrhea and vomiting, but can also manifest on the skin and the respiratory tract.

Allergy treatment includes desensitization, which intends to reduce the reaction towards a certain allergen by putting the patient in contact with small doses of it.

However, the treatment that is used the most is based on medications that stop the inflammatory response caused by the allergen. These include antihistamines, corticosteroids, bronchodilators and epinephrine.

Regardless of the type of allergy and the allergic response, it is very important to inform doctors about them, if you are aware of them.

See Also: Seasonal Allergies: Allergens, Symptoms, And Treatment

Sometimes, allergic reactions can be harmless, but with time, they can get worse. Also, it is very common that allergic patients have more than one allergy, which is why sometimes it is very difficult to determine what is exactly causing the allergic reaction.

If you have allergies or suspect you do, you could see a specialist, who will perform specialized diagnostic tests that will help to determine the source of your allergy and hopefully, the right treatment for it. 

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