Allergy and Immunity: What’s the Difference Between Fighting Viruses and Reacting to Allergens?
by Nataliia Bohdanova
Many people believe that having allergies is a sign of a strong immune system. In reality, it’s quite the opposite: allergy is an immune system error, where harmless substances are mistakenly perceived as dangerous threats.
How the Immune System Fights Viruses
A virus is a true invader. It enters the body’s cells, uses them to replicate, and damages tissues.
The immune system correctly identifies the virus as a threat and responds:
- It detects viral proteins on the surface of infected cells.
- It activates specialized killer cells (cytotoxic T-lymphocytes).
- It produces antibodies to neutralize free viral particles.
- It triggers inflammation to destroy infected tissues and restore normal function.
Result: the immune system eliminates the real threat and helps the body recover.
How the Immune System Reacts to Allergens
An allergen is typically a harmless substance, such as plant pollen, dust, nuts, or animal dander.
Most people have no reaction to these substances.
However, in allergic individuals, the immune system mistakenly treats them as if they were deadly threats.
The process looks like this:
- Upon first contact, the immune system “remembers” the allergen and starts producing specific IgE antibodies against it.
- These antibodies attach to mast cells.
- On subsequent exposure, the allergen binds to the IgE on mast cells, triggering the release of histamine and other inflammatory mediators.
- Symptoms such as itching, swelling, sneezing, and airway spasms appear.
Result: the body wastes resources fighting something that poses no real danger.
Why Are Allergens Dangerous Only to Some People?
This is determined by genetics, immune regulation, and environmental factors:
- Genetic predisposition can increase the likelihood of developing allergies.
- Imbalance in immune system responses raises the risk of hypersensitivity.
- Environmental influences, lifestyle, and gut microbiota composition also play important roles.
Thus, allergens are selective: harmless for some people, while causing dangerous reactions in others.
What Are Allergens: Types and Examples
Allergens are substances that can trigger allergic reactions in susceptible individuals. Major categories include:
- Food allergens: nuts, dairy products, eggs, fish, shellfish.
- Pollen allergens: tree pollen (birch, alder), grass pollen, ragweed.
- Indoor allergens: house dust, dust mites, animal dander.
- Drug allergens: antibiotics (e.g., penicillin), certain medications.
- Insect venoms: bee, wasp, and hornet stings.
Why Does the Immune System Treat Allergens as Enemies?
Several hypotheses explain this phenomenon:
- Hygiene hypothesis: In overly clean environments, the immune system “gets bored” and starts reacting to harmless substances because there are few real pathogens.
- Structural similarity: Some allergens resemble parts of pathogens, confusing the immune system.
- Cross-reactivity: The immune system reacts to an allergen because it closely resembles a previous dangerous agent.
How to Understand Allergy Correctly
Allergy is not a sign of a strong immune system, but rather a malfunction in its function.
The immune system mistakenly perceives harmless substances as a serious threat and launches a powerful defensive reaction.
Although allergens themselves (such as nuts or pollen) are safe for most people, it is the immune response in predisposed individuals that can become extremely severe and even life-threatening.
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