In normal conditions, our immune system is used to protect us against viruses and bacteria.
If there is either no development of tolerance or that tolerance vanishes, the immune system turns against those proteins (allergens) and reacts. 𝗪𝐡𝐚𝐭 𝐚𝐫𝐞 𝐭𝐡𝐞 𝐜𝐨𝐦𝐦𝐨𝐧 𝐚𝐥𝐥𝐞𝐫𝐠𝐞𝐧𝐬?
An initial sensitisation is needed before a reaction can occur.
The immune system considers the allergen as an “invader” and seeks to destroy it by using IgE, which leads to the release (among others) of histamine.
Histamine then causes blood vessels to increase in size, which in association with other chemicals, leads to allergy symptoms.
𝘛𝘺𝘱𝘦 𝘐𝘝 (𝘥𝘦𝘭𝘢𝘺𝘦𝘥 𝘳𝘦𝘢𝘤𝘵𝘪𝘰𝘯𝘴) – 𝘯𝘰𝘯-𝘐𝘨𝘌 𝘮𝘦𝘥𝘪𝘢𝘵𝘦𝘥
Reactions to food protein are likely due to an immature immune system of the gut mucosa. They are mediated by T Cells.
This is the most common kind of allergy in the first few years of life.
As it takes several hours between ingestion and symptoms to show, it tends to go under recognised, leading to significant parental frustration.
The Symptoms depend on what the allergen is and the type of reactions.
They vary from very mild to life-threatening (Anaphylaxis and FPIES – which I will talk about in another post).
The ones below are IgE mediated but have a look at the table for signs of delayed reactions.