The immune system’s role in horse allergies involves an inappropriate response to harmless substances, leading to allergic reactions or hypersensitivity. These reactions occur when the immune system mistakenly identifies a substance as a threat and mounts a defense against it. This process involves reactive lymphocytes that trigger a response upon re-exposure to the antigen.
How Does the Immune System Cause Allergic Reactions in Horses?
The immune system recognizes foreign molecules but can’t always distinguish between harmful and harmless ones. In allergic reactions, the immune system responds to innocuous substances as if they were dangerous, initiating mechanisms that, while beneficial for eliminating microbes, can damage tissues. This inappropriate response is termed allergy or hypersensitivity.
What is Type I Hypersensitivity?
Type I hypersensitivity, also known as atopic or anaphylactic hypersensitivity, involves IgE antibodies, mast cells, and basophils. In this type of reaction, the body produces IgE antibodies in response to an allergen. These antibodies bind to mast cells and basophils, which then release substances like histamine, leading to inflammation and allergic symptoms.
What are Common Allergens for Horses?
Allergens are typically polypeptides with carbohydrate groups, resistant to drying. Common allergens include pollen, fungal spores, animal dander, plant seeds, house dust, and certain foods. The main allergen in house dust is the excreta of mites that live on skin scales.
What Happens During an Allergic Reaction?
During a Type I hypersensitivity reaction, acute inflammation occurs, marked by fluid seepage and blood vessel dilation, followed by granulocyte infiltration into tissues. If an allergen enters the eyes and nose, it can cause hay fever symptoms like swelling, redness, and mucus secretion. If it penetrates the lungs, it can cause asthma symptoms like bronchial tube swelling and breathing difficulties. Injected allergens can cause wheal-and-flare reactions with swelling and skin redness. If allergens enter the bloodstream, they can cause hives and, in severe cases, anaphylaxis, characterized by a drop in blood pressure and breathing difficulty.
What is the late-phase reaction?
Following the immediate reaction, a late-phase reaction may occur, involving granulocytes, lymphocytes, and macrophages. This prolonged reaction can last for a day or two and is a feature of asthmatic attacks. Prolonged IgE-induced reactions can also cause atopic dermatitis, a skin condition with persistent itching and red patches.
What role do genetics play in allergies?
About 10% of the population is considered atopic, having an increased tendency to produce IgE antibodies. This tendency often runs in families, suggesting a genetic component, though no single gene is responsible.
The immune system plays a central role in horse allergies by initiating hypersensitivity reactions to harmless substances. These reactions involve various immune cells and antibodies, leading to inflammation and a range of allergic symptoms.
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