October 16, 2025

Sophia Nguyen

Fountain Valley High School

11th Grade

Have you ever stopped to wonder why you’re allergic to pollen? Allergies are a response from the immune system to foreign substances, such as pollen, animal dander, etc. In essence, an allergy is like a false alarm. It’s your body mistaking harmless environmental particles for dangerous invaders. Allergies affect not only people's diets but also their lives as well. In the United States, 1 out of 3 adults reported having at least 1 allergy, and 1 in 4 children reported having at least 1 allergy, which shows how widespread having an allergy is.

Allergies develop through complex interactions between the immune system, genetics, and the environment, which explains why some people get allergies and some don’t. For example, people who are allergic to dogs, why do they get allergies? The immune system misidentifies harmless substances, in this example, dog dander, and labels them as allergens, threats to the body. When this happens, the body prepares for battle, activating immune cells meant for fighting parasites and foreign intruders. IgE (Immunoglobulin E) is found on the surface of immune cells such as basophils, mast cells, and eosinophils (all of which regulate allergic responses), which allow them to identify intruders. These IgE antibodies recognize the dog dander as foreign, which triggers the release of histamines along with a melody of chemicals your body uses, causing an allergic reaction. Histamines cause the symptoms of an allergic reaction, symptoms like vasodilation (widening of blood vessels), swelling, hives, a runny nose, etc. So, your runny nose is caused by a misunderstanding between the body and the allergen.

But how do genes tie into allergies? Allergies tend to run in families. If both parents have an allergy, the child’s risk of having that same allergy rises significantly. However, there is no singular gene that causes allergic reactions. Allergies are polygenetic in nature, meaning that multiple genes cause allergies. For example, defects in the filaggrin gene, a gene vital for maintaining skin barrier function, are strongly correlated to people developing allergies. By allowing allergens easier entry, filaggrin mutations can cause eczema or food sensitivities. Additionally, researchers have also identified dozens of genes influencing IgE production and inflammatory responses, which shows the complexity of the relationship between allergies and genes.

The environment also plays a large part in why we develop allergies. Owning a dog as a child can “train” your immune system to reduce allergies to them. Childhood exposure to allergens in general can reduce the immune system’s reactions. This concept is known as the hygiene hypothesis. The hygiene hypothesis suggests that increased exposure to bacteria/viruses trains the immune system so it is less likely to overreact to allergens but also is stronger. Preventative strategies, such as early exposure to potential allergens, are proven to lower risk. Moreover, immunotherapy utilizes the same principles to desensitize the body to allergens. Another example is that environmental pollution and climate change are worsening allergies, especially in urban areas. Air pollution degrades and damages pollen, which causes it to be a more potent allergen.

So why do only some people suffer from allergies? Some immune systems recognize allergens but do not overreact due to proper intervention from immune cells. Additionally, some people are predisposed to genetic protection. Certain genetic profiles suppress overactive IgE responses. While their immune systems also have a reaction to the allergens, it is far more muted and regulated by their bodies. Additionally, a balanced gut microbiome is proven to affect the development of food allergies. A balanced gut microbiome helps maintain immune tolerance, making people with more diverse gut bacteria less likely to develop allergies. So, eating well really does help you stay healthy.

In conclusion, allergies stem from a complex blend of genetic predisposition, environmental factors, and immune response, causing some to develop them and some to not. Studies on immunology and allergies continue advancing, but until there come to be better solutions, allergy season will continue reminding us that our bodies are a bit too enthusiastic in protecting us.