Getting to know

The immune system is the structure that guards our body from aggressive invaders, like microbes (viruses or bacteria), parasites (i.e. worms) or chemicals. If we did not have an immune system, these aggressors coming in contact with our body would damage it and might even cause our death.

You should see the immune system as a defending army, scattered all around the body and surveying continuously every second all the substances and particles coming in contact with it. The soldiers of this army are a wide variety of cells. Similar to an army, each one of these cells has a clearly defined role and when they act they respect a certain hierarchy (there are generals, officers, elite forces and simple soldiers).

In order to be able to understand what happens to your body when you have an allergic attack you must meet some of the cells of the immune system. 

(also known as Th lymphocytes or Th cells) are the almighty generals of this defending army. When the body gets in contact with an aggressive attacker they tell all the other cells when and how to get in action.

(or B cells) are officers under the command of Th cells who produce specialized weapons to fight the enemy. These weapons are called antibodies or immunoglobulins. B cells can produce five different types of antibodies called Immunoglobuline (Ig) G, M, A and D. For every aggressor T cell is instructing B cell the kind of antibodies it must to produce. Production of antibodies is a highly specialized process in which each antibody is made to match perfectly the aggressor (the aggressor and the antibody match each other like the key and its lock). This is very important because the role of the antibodies is to help immune cells to recognize the aggressor; therefore they must be able to identify them highly accurate. 
In allergy your B cells produce high quantities of IgE which has the ability to recognize the allergen. 

are the watch soldiers who’s role is to spot any aggressor that attempts to enter the body. These cells have long projections which form a tight network. No substance getting into our body can pass unnoticed by this network; however dendritic cells are simple soldiers which cannot kill the attacker; all they can do is to immobilize some of the invaders and warn the leader of the army (the T cell) that the body has been attacked.

are regular soldiers. Pay good attention to these cells because they are essential cells in allergy. These cells cannot kill the aggressors but their role is to hold back the invasion of the enemy until more specialized forces could come to destroy it; also their role to ease the influx of these forces into the battle field. How do they do so? By releasing rapidly acting substances which cause changes in your body which make the environment unfriendly for the aggressors Mast cells have these substances stored in granules insides them and consequently when signalled about the presence of the enemy they can release these substances within minutes. Histamine is the most important of mast cell substances and one of the main responsible for the symptoms you manifest during the allergic attack. 

are trained killers. Their weapons are aggressive substances stored in granules inside the cell (similar with the cells above only that the substances are different). When released out of the cell, these substances can kill the invaders. (These substances are a little bit like caustic soda. Think what would happen to your skin if you would put your hand a solution of caustic soda……So now, you know what is happening to a worm when a similar kind of substances released from eosinophils get in contact with its skin. Deadly, no? ) Now that you know who are the characters we can now go further and see how they interplay and how do they cause the symptoms you experience during the allergic attack