TECH & SCIENCE
AS I sit writing this article, my eyes are itchy, my nose doesn’t know whether it’s running or congested, and I’m honestly pretty tired after several sneezing fits throughout the day. I’m in the middle of moving house, you see, and between the dust bunnies that took up residence beneath the fridge, and the accursed flora that decides to spawn and spread its foul, evil pollen everywhere during Spring, my immune system is having a meltdown and is intent on obliterating - with extreme prejudice - every tiny foreign substance that enters my body. The whole process is exhausting - as those of you who suffer from hayfever can attest to. That’s why this week, I thought I’d dive in and find out exactly what is going on inside our bodies when we suffer from hayfever.
What is hayfever?
The first thing to note about hayfever is that it isn’t necessarily triggered by exposure to hay, and it usually doesn’t result in a fever. The confusion surrounding the name arose in the 1800’s when the symptoms were misattributed to the scent of fresh cut hay. This likely arose due to the fact that farmers often cut hay around the same time of year that the majority of pollen is floating around in the air. The proper term for the condition is actually ‘allergic rhinitis’, which basically means inflammation and irritation of the mucous membrane in the nose. The allergic response to pollen is similar to that of dust and cat hair, or, as I like to call them, ‘the Devil’s Trifecta’. When pollen first enters your body, it’s immediately met with the ‘security guard’ of your body - the ‘antigen presenting cell’. This cell engulfs the pollen, pushing small pieces of it out onto its own surface. This is a vital step as other immune cells can’t detect foreign invaders and rely on the antigen presenting cell to signal the warning and make the foreign invader visible to them. One cell in particular, the T-cell, will alert even more immune cells once the antigen presenting cell has engulfed the foreign body. The most important cell to be alerted is the B-cell, which, once hearing of a foreign invader, will begin producing large amounts of antibodies called immunoglobulin E. The antibodies will then disperse into the blood and attach themselves to two more types of immune cells - mast cells and basophils. When the allergen next enters your body, antibodies on the mast cells and basophils will catch the allergens, making them stick to the immune cells. When this happens, the mast cells and basophils will undergo a process called degranulation, where they release large amounts of chemical compounds known as histamines. These chemicals trigger the dilation of vessels in your nose and heavy mucous secretion resulting in a runny nose, sneezing and congestion.
Why does hayfever occur?
In a normal immune response, where the foreign invader is actually dangerous, this process is vitally important in protecting our body from bad illnesses and diseases. It is the groundwork that allows the rest of the immune system to get to the infection quickly while they are caught by the mast cells and basophils, and repair any damage to the body. In a hayfever sufferer, the immune system is simply overreacting to a innocuous invader, such as dust particles or pollen, resulting in frustrating symptoms that, in essence, make you feel unwell even when you really aren’t. While scientist still haven’t really gotten to the bottom of why some people suffer from hayfever while others do not, some researchers have hypothesised that it is due to over sanitised environments, pollution, or potentially vitamin D deficiencies in childhood. As someone who has contended with this condition their whole life, I’m inclined to believe it’s a combination of all three of those hypotheses.
What are antihistamines?
One way to contend with the symptoms of hayfever is to take an antihistamine. An antihistamine, as they pertain specifically to allergic reactions, neutralise the effect of the histamines released by the mast cells and basophils. No histamines, no dilation of vessels in the nose - no mucus, sneezing and itching. Okay dear allergy sufferer, now that we’ve dived deep into the cause and effect of hayfever, do you feel any better? No, I can’t say I do either. Bring on winter.
AH-CHOO: An approximate diagram of an allergic reaction to pollen.