• Allergy is a hypersensitivity reaction initiated by an immune response after exposure to an allergen.
• The immune response can be anti-body mediated or cell mediated.
• Atopy is a personal or familial tendency to became sensitised and produce IgE antibodies to ordinary exposure to allergens.
• Allergens are usually proteins and exist naturally.
• It occurs when the immune response fails to develop tolerance to the specific protein.
• The future exposure to that allergen will lead to an immune response via IgE antibodies and mast cell degranulation or cell mediated reactions.
• Allergies usually develops in early life but can occurs later in life.
• The gold standard of Allergy testing is skin prick testing. This can be done in most patients for most allergens causing a IgE-medicated reaction. The histamine response is measured and that is the reason patients need to stop takin antihistamines prior to testing.
• Blood tests are sometimes needed to determine cross reactivity and if patients have severe skin involvement or not able to stop antihistamines.
• Allergen challenge test are done in some cases.