Allergens and Immune System




A substance usually harmless that causes an allergy, for example house dust mites, pollens, insects, foods and some medicines.

In Bangladesh, particularly, duck's egg, ilish fish, fresh/dried shrimp/prawn, beef, aubergine, moulds,cockroach, dusts and exhausts are common allergens.

Allergen is also called antigen which can activate and alert the innate immune system to 'any danger' through pattern recognition receptors. This response directs/activates the adaptive immune system to drive an IgE mediated response.Most common categories of allergens, which can drive IgE medicated responses are food allergens, aeroallergens, venom and drug allegens.These are called exogenous antigen (non-self) that have entered in to the body from outside/external environment for  example by inhalation, ingestion or injection. Some other antigens may originate from within normal cells in our body called endogenous (self-antigen), the immune system usually does not react to self-antigens. This can be generated as a result of cell metabolism or viral or intracellular bacterial infection. The fragments are then presented on the cell surface
 in the complex with MHC class I molecules. If activated T cells recognize them, the they secrete various toxins that cause the lysis.

Acccording to the characteristics allergens are classified in to 3 groups such as Class 1 which typically storage proteins in food and heat resistant, Class 2 pathogens related protein in fruit and nuts, heat intolerant and other carbohydrate cross reacting determinamnt such as venom and certain foods.

Immune system:

It is the body's defence against infectious microorganisms and other invaders comprising special cells, proteins, tissues, and organs.
Our body can live with many microorganisms and cope with various substances from the environment. However, the microbes and the things which they specify as harmful or invader then things go wrong.
Using an instrinsic/natural system, our bodies strike the invaders very quickly even in minutes or hours in order to provide us with the appropriate defence.This involves some cells and special micro-proteins (Complement, Toll like receptors) called innate immune system.
In addition to this innate immune system our bodies have an ability to evolve an adaptive immune system which can adapt an optimal 'attack strategy' against a specific microbe or substance (allergen). Although their response is delayed and may take days or even weeks, they have a very strong and regulated mechanism of invader recognition such as memory cells.
Adaptive immune system kicks off antibody and T cell response. Important cross talk between the innate and adaptive immune systems, can provides us with a very strong defence against the invader.