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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Immune dysregulation | 3/3 | https://en.wikipedia.org/wiki/Immune_dysregulation | reference | science, encyclopedia | 2026-05-05T07:29:34.278736+00:00 | kb-cron |
== Allergy == Allergic reactions are misdirected reactions of the immune system to substances commonly found in the environment. Allergens elicit a The immune response, including the involvement of IgE, mast cells, Innate lymphoid cells 2 (ILC2), eosinophils, and basophils. Allergy symptoms are often related to the body's efforts to expel the allergen from the body and to protect it from further exposure to the allergen. Allergic reactions increase the production of mucus by goblet cells on the mucosa. The production of mucus is promoted by IL-13 from ILC2 and Th2 cells. Higher mucus production then creates stronger barrier protection and supports runny nose, coughing, or sneezing. Removal of the allergen from the body by sneezing, coughing, vomiting, or diarrhea is enabled by the activation of peristalsis and contractions of the smooth muscles of the digestive and respiratory systems. Activation of smooth muscles occurs after the action of histamine, which is released by mast cells. Manifestations of allergies generally aim to eliminate the body's allergen. This is also related to hearing the flushing of antigens in the eyes or to attempts to achieve mechanical removal of the surface of the organism. Allergies can be caused by genetic and environmental factors. Some theories support the view that allergies enter as protection against environmental substances that can disrupt the body, such as insect venom. Another possibility of activating an allergic reaction is the similarity of some allergens to the molecular patterns of parasites against which the immune system also uses a type 2 immune response. The hygiene hypothesis then relates to changes in lifetime exposure to pathogens in developed countries. In the case of insufficient exposure to pathogens and insufficient stimulation of the Th1 response during an individual's development, the balance between Th1 and Th2 type responses may predominate to proallergic Th2. The theory is supported by the more frequent occurrence of allergies in developed countries compared to developing countries, but also by the higher incidence of allergies in cities compared to villages, where individuals can meet with pathogens of farm animals. Children from small families are also more likely to have allergies than children from families with more children, where there is more frequent contact with pathogens from siblings. Another environmental factor that may promote the predisposition to allergies is a reduction in the diversity of the microbiome – this affects the diet of individuals, but also the diet of the mother during pregnancy, method of delivery, breastfeeding, antibiotics, and the presence of domestic or farm animals in the normal life of individuals.
== References ==