This article was originally published on RealClearScience.
When I was a kid, I remember going to the allergist’s office and having him stick me in the back with several dozen tiny needles, each filled with a common allergen such as cat hair. After a few minutes, my back became itchy, and patterns of bright red bumps emerged like this, indicating an allergic reaction. My doctor, along with my parents, stood over my back, pointing at all the pretty colors. He informed us that I was mildly allergic to dogs and terribly allergic to cats, but not at all allergic to goats. (We ended up getting a dog, anyway, and I spent the next several years getting allergy shots, too.)
This modern-day form of torture, however, soon may be coming to an end. Researchers report in the journal Nature Communications that a new blood test could eliminate the need for allergy skin prick assays. Its mechanism of action is nothing short of a cellular Rube Goldberg machine, built using the tools of synthetic biology.
Instead of jamming tiny needles into your back, an allergist would simply draw your blood and mix in a sample of allergen. (See middle panel.) If you are allergic to, say, cat hair, your blood will contain a type of antibody called IgE that will bind to it. IgE bound to the allergen will simultaneously bind to an IgE receptor on the surface of mast cells and basophils (left panel), triggering these two types of immune cells to release histamine. (That is why you take anti-histamines to treat allergies.)
Now, the authors’ clever cell-based assay takes over. (See right panel.) Histamine will bind to a histamine receptor on the designer cells. This triggers a whole cascade of events, ultimately culminating in the production of Citrine, a protein that fluoresces yellow. The intensity of the fluorescence correlates with the severity of the allergic reaction.
Sickly children everywhere, rejoice!
Source: David Auslander, Benjamin Eggerschwiler, Christian Kemmer, Barbara Geering, Simon Auslander & Martin Fussenegger. “A designer cell-based histamine-specific human allergy profiler.” Nat Commun 5:4408 (2014). DOI: 10.1038/ncomms5408
(Photo: Allergy skin test via Skoch3/Wikimedia Commons)