For an allergy to exist, allergen sensitisation must first occur. Antigen-presenting cells, including macrophages and dendritic cells, are responsible for detecting the allergen. This can happen in a variety of ways, including inhalation via the nose and lungs, as well as through the skin and the gastrointestinal tract.
When cells containing an antigen interact with an allergen, it is perceived to be an invader, even though we wouldn’t normally consider the substance harmful. Subsequently, the allergen is then absorbed into the antigen-presenting cell, processed and then displayed on the surface of the cell.
Next, the cell then migrates and presents the allergen. This process stimulates the B-cell and produces antibodies specific to the allergen. From here, these particular antibodies, (IgE) are then released and can attach themselves to receptors on various surfaces of other cells in the mucosal surfaces and on subsequent basophils contained within the blood.
There is a period of sensitisation, and afterwards comes a period of latency, then on subsequent re-exposure to the allergen, the allergic response is triggered. In this process, an allergen can connect with the IgE on the surfaces of the mast cell, and this causes the cell to release nasty and inflammatory cell mediators. These include histamines and other mediators, all of which act differently and create a variety of symptoms in different organs.
The key to fully defining allergy pathogenesis and developing novel therapeutic possibilities may be in further understanding the gut microbiome and advancing research into epigenetics.
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