What is an allergy

It’s spring, and Maria and Sofia are playing in the park. They’ve been outside for about fifteen minutes, when Maria starts sniffing and sneezing, and her eyes start watering. What’s wrong Maria? Are you getting ill? No, it’s the pollen.

Is pollen making you sad? No! I’m allergic to it! Maria’s body, specifically her immune system, is not working properly. Her immune system recognises pollen as harmful to the body.

That’s a mistake. Pollen is just harmless particles. But when Maria comes into contact with pollen, her immune system triggers a chain of reactions, to protect her body from the pollen. This is an allergic reaction. So she starts sneezing, her nose starts running, her eyes water.

These are the signs, or symptoms of her allergic reaction. But Sofia’s body doesn’t react in the same way. She can be around pollen any time and doesn’t get an allergic reaction. So what happens inside Maria’s body? Well, the very first time Maria came into contact with pollen, one part of her immune system reacted to it.

It was the special immune cells, called B-cells, which reacted. They released protein molecules, called antibodies, into the bloodstream. Once in the bloodstream, antibodies attached themselves onto one type of white blood cell. This type of white blood cell is called a mast cell and they are found all over the body. This chain of reactions in Maria’s immune system is how Maria became allergic to pollen.

Every time Maria is exposed to that type of pollen again, the pollen attaches itself to antibodies on the mast cells. When that happens, mast cells release substances, such as histamine. It’s histamine that causes the symptoms of the allergic reaction. But pollen is not the only thing people can be allergic to! Besides pollen, food such as tree nuts, peanuts, eggs, cow’s milk and shellfish, contain the substances that people are most often allergic to.

Animal fur can also contain such substances. We call these substances allergens. So people are allergic to different things and their allergic symptoms can be different too. Besides a stuffy nose, the symptoms of an allergic reaction can be skin rash, coughing, shortness of breath, tightening of the chest, headaches or nausea. In some cases, allergies can also cause a very severe condition in which blood vessels expand, which may drastically lower blood pressure.

This condition is called anaphylaxis or anaphylactic shock, and it may be life-threatening. In which case, the person needs to seek medical help immediately or get an adrenaline shot. We don’t know why some people are more likely to develop allergies than others. We also don’t know how to cure or prevent allergies yet, although some people can become less sensitive to allergens over time. The best way for people with an allergy, to not get an allergic reaction, is usually to avoid the thing they are allergic to.

But sometimes that’s difficult. For example people with pollen allergy can’t always stay indoors the whole time plants are blooming and there’s pollen in the air. For those people, they can take medication. This medication doesn’t stop the allergic reaction, but it helps treat the symptoms. Let’s go home, I don’t want you to cry...

That sounds like a great idea.