Which type of hypersensitivity is involved in reactions like anaphylaxis and asthma?

Type 1 hypersensitivity is characterized by immediate allergic reactions, which are mediated by immunoglobulin E (IgE) antibodies. In this type of hypersensitivity, exposure to an allergen triggers the activation of mast cells and basophils, leading to the release of histamines and other inflammatory mediators. This rapid immune response can result in symptoms such as bronchoconstriction, increased vascular permeability, and vasodilation, manifesting in conditions like anaphylaxis and asthma.

Anaphylaxis is a severe, systemic reaction that can occur within minutes of exposure to an allergen, resulting in life-threatening symptoms such as difficulty breathing, swelling, and a drop in blood pressure. Asthma, on the other hand, involves bronchial hyperreactivity and airway inflammation, often triggered by allergens and characterized by wheezing, coughing, and shortness of breath. Both conditions are fundamentally linked to the mechanisms of Type 1 hypersensitivity, underscoring its role in these immediate allergic reactions.