Do pets make you sneeze?
Well, you’re not alone: an estimated ten percent of the population is allergic to animals. And the animal responsible for the majority of those allergies is Felis domesticus–your basic household cat.
Being the cat person that I am, this strikes me as a terrible, terrible, thing, worthy of serious research.
Fortunately, actual scientists agree, and in the last week news has come of two promising approaches to treating cat allergies–and, by extension, other types of allergies, as well.
We don’t think of allergies as a disease, but they can make you just as miserable as many infections. That’s not surprising, since the symptoms of allergies (sneezing, watery eyes, nasal congestion, a rash, an upset stomach, hives, lung spasms, or a combination of any or all of these) and those of disease result from the activation of your immune system. The difference is that in the case of an allergy, the response is to something harmless rather than to dangerous germs.
The allergic reaction is, therefore–sometimes literally–overkill. The most severe allergic reaction is anaphylactic shock, characterized by a severe drop in blood pressure, an itchy rash or hives, breathing difficulty, abdominal pain, swelling of the tongue or throat and diarrhea. It can lead to asphyxiation and death.
An allergic reaction begins when the immune system, mistaking, say, ragweed pollen for a virus, manufactures special antibodies called immunoglobulin E, or IgE for short. These combine with the allergen molecules and attach themselves to special cells that release histamine and other compounds that affect the blood vessels and mucous membranes, leading to swelling and congestion.
One method long used to try to treat allergies has been desensitization, injecting small amounts of the substance that causes the allergy under the skin: enough to cause the body to make antibodies, but not enough to trigger an allergic reaction. Through repeated injections, the body learns not to attack the substance. But this is both time-consuming and uncertain: sometimes it causes serious reactions.
If the research announced this week pans out, though, things could be looking up.
In one study, published in Nature Medicine, researchers from UCLA, led by Dr. Andrew Saxon, reported they had successfully combined pieces of an allergy-provoking cat protein with a piece of human antibody called IgG Fcg1, an antibody which, unlike IgE, normally suppresses the immune response. They called the compound GFD, for gamma Felis domesticus. The idea was that although the immune system would still recognize the cat allergen as an invader, the human antibody would tell it not to attack it.
Apparently, it works. In human cell cultures, GFD resulted in 90 percent less histamine production than cat allergen alone did. The researchers discovered much the same results in mice designed to be allergic to cat saliva and dander: GFD blocked the immune system overreaction in two different types of allergic mice, who didn’t develop airway inflammation like they normally would have.
If the treatment makes it to humans, the hope is that over time the immune system will retrain itself to no longer react to the cat allergen. And the study holds out hope that other allergies, such as the very dangerous peanut allergy, could be treated in a similar fashion.
In the other related study, published in the open-access medical journal PLoS Medicine, a team from Imperial College London, led by Mark Larché, reported that treating individuals with a synthetically produced peptide (amino acid chain) derived from cat allergen resulted in the production of T cells (white blood cells) that suppressed another type of T cell that would normally lead the way in the immune system response.
By shedding light on the mechanism of allergy development–there’s some indication that people who are exposed to pets early on in life are less likely to develop allergies later on–this work may point the way to an eventual vaccine designed to prevent allergies from ever getting started.
All that is still in the future, of course (as medical breakthroughs always seem to be). And in the case of the UCLA study, we all know by now that mice are not people. (As an aside, if I were a mouse, I’d be happier if scientists were making cats allergic to mice rather than the other way around.)
But for allergy sufferers, any hope of a breakthrough, even a few years down the road, may just make the next round of sneezing a little easier to bear.