My confusion with IgE antibodies and allergy?

[sameeralord]

Hello everyone,

There was a simple question given, where there was a bee sting on a guy and the question asked was what is the antibody involved. The answer is IgE. Now my question is when there is bee sting for the first time, why do we called it an allergic reaction. I mean for an allergy to occur don't we have to be exposed to the antigen second time, so IgE attached to Mast cells will release histamine 2nd time. Also why aren't other antibodies like IgA ect not involed in a bee sting. Thanks

 

[Jack the Stri]

You are correct, the allergic reaction only occurs after the second sting and due to presence of IgE antibodies. IgA is not involved in this because it functions in mucosal immunity.

 

[sameeralord]

You are correct, the allergic reaction only occurs after the second sting and due to presence of IgE antibodies. IgA is not involved in this because it functions in mucosal immunity.

Hey thanks for help Jack I have a quick clarification though. IgA protects body surfaces. It is synthesized by secretory epithelial cells. So it should be found in skin. Is the reason it is not involved is because it protects against microorganisms and IgE against allergens.

 

[bobze]

Hey thanks for help Jack I have a quick clarification though. IgA protects body surfaces. It is synthesized by secretory epithelial cells. So it should be found in skin. Is the reason it is not involved is because it protects against microorganisms and IgE against allergens.

Yea kind of. Remember that immunoglobulins are 3d things that bind to different stuff. IgE mostly has impacts on mast cells and basophils and incite them to release their granules (degranulation). Mast cells and basophils contain granules with histamine and heprain (probably the two most important components anyway) which cause "allergic" reactions.

Specifically in the respiratory system (which just make matters confusing for you, the respiratory system has opposite reactions of the systemic parts of the body) histamine causes vasoconstriction. Which makes sense if you think about it from your bodies point of view. If you are breathing "something bad" the body wants to restrict the air inflow to those parts of the tracheobronchial tree, restricting intake of the irritant. The problem occurs when too much histamine is released and you have global (relative to the lung) vasoconstriction which restricts total air flow. In the systemic parts of the body (the nose for instance), histamine causes vasodialation and increased secretions. Again, makes sense from your body's POV. If you have a pathogen invading the nose, you want more blood flow (increases the availability of leukocytes) and more mucous to "flush" the pathogen out.

Secretory IgA (~10% of our IgA) is produced by plasma cells which constitutively secrete IgA which is then transported across the mucosal epithelium and out of the body (via bodily secretions) and mostly aids in interference of bacterial pathogenesis or assists in opsonization (searchable term) of pathogens.

 

[LudusRex]

Hello,

Thank you for your question. IgE antibodies are a type of immunoglobulin that is involved in allergic reactions. When an individual is exposed to an allergen, such as a bee sting, for the first time, the body's immune system recognizes it as a foreign substance and produces IgE antibodies. These antibodies then bind to mast cells, which are a type of immune cell found in tissues throughout the body.

During a subsequent exposure to the same allergen, the IgE antibodies on the mast cells recognize the allergen and trigger the release of histamine and other inflammatory mediators. This causes the symptoms of an allergic reaction, such as swelling, itching, and inflammation.

It is true that for an allergic reaction to occur, the individual must be exposed to the allergen a second time. This is because the first exposure is necessary for the body to produce IgE antibodies. However, it is important to note that not everyone who is exposed to an allergen will develop an allergic reaction. Some individuals may have a genetic predisposition to produce more IgE antibodies in response to certain allergens, making them more susceptible to allergies.

As for why other antibodies like IgA are not involved in a bee sting, it is because IgE antibodies are specifically designed to respond to allergens and trigger an allergic reaction. IgA antibodies are primarily involved in defending against infections in the mucous membranes, such as those in the respiratory and digestive tracts. They are not as specialized in recognizing and responding to allergens.

I hope this explanation helps to clarify the role of IgE antibodies in allergic reactions. If you have further questions, please don't hesitate to ask. I am always happy to discuss and explain scientific concepts.