Text on screen: 'Reactions, Everyday Chemistry. Produced by the American Chemical Society.' Shot of flowering tree branches. Text on screen — 'Spring at last!'
NARRATOR:
So springtime is upon us, and the weather's beautiful. Flowers are blooming and people are breaking out their shorts and T-shirts.
A montage of shorts and T-shirts appear. Text on screen — 'Finally!'
NARRATOR:
But if you're like me, you're miserable and stuck at home with a runny nose and puffy eyes.
A woman sits up in bed and sneezes heavily. Text on screen — 'Why?'
NARRATOR:
But why do we have to suffer from these horrible allergies?
Interview with Calman Prussin, M.D. from the National Institute of Allergy and Infectious Diseases.
CALMAN PRUSSIN:
An allergy is actually a mistake that the immune system is making. Normally we make antibodies to fight germs and to recognise germs. And in this case, the immune system has made a mistake, and instead is making an antibody that recognises harmless things such as pollens or animal dander.
NARRATOR:
Inside every allergy sufferer there lies an immune system that mistakenly produces an antibody known as immunoglobulin E. When these unfortunate people breathe in the pollen, the antibody triggers an allergic reaction. But we're not talking about just any kind of pollen here. It's commonly though that allergy-causing pollens come from big flowers like this…
Shot of a sunflower.
NARRATOR:
..but actually, that pollen is too heavy to go airborne. Allergies are caused by pollen from trees and grasses that's small and light enough to be carried by the wind.
CALMAN PRUSSIN:
When the immune system of somebody who's allergic recognises these pollens, immunoglobulin E activates cells of the immune system — mast cells — and these mast cells release chemicals that cause allergic reactions.
Cartoon of a mast cell — a potato-shaped cell with four C-shaped receptors poking out and a series of holes on its lower section. Pollen falls into the receptors, then the holes drop chemicals.
CALMAN PRUSSIN:
One of the most well-known chemicals to cause allergic reactions is histamine. Histamine is a small organic molecule, and so the way histamine works as this small chemical messenger is that it finds a receptor that's on many, many cells of the body called a 'histamine receptor', and sends that cell a message. For example, in the blood vessels, it binds to that receptor, it tells that blood vessel to become leaky, which causes the runny nose that you get. Or, for example, there are receptors on nerves which the histamine will activate, and that gives you the sensation of that itchy nose that you might feel during pollen exposure.
NARRATOR:
So, if you're wheezing and sneezing this spring, try to stay indoors early in the morning when there's more pollen floating about.
Shot of masses of pollen flaking off plants. Text on screen — 'No-one wants this.'
NARRATOR:
But if you have to go out there, at least pack some tissues and maybe some antihistamines.