Woman with cat sneezing

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About 30% of people have an allergy to dogs and cats, according to the Asthma and Allergy Foundation of America, and cats cause people to react twice as often as dogs. While some people are able to treat their symptoms so that they can live in the same house and still breathe, others are not and therefore must avoid contact with cats. In some situations, this means the cat and the person must or should live apart because breathing is an underrated pleasure.

In almost all instances of allergic reactions, the person experiencing the reaction is the focus for developing ways to decrease this unwanted response. Your immune system reacts to the pet dander and gets all hyperactive, so you take something for it. But when it comes to people with cat allergies, researchers are changing the focus: instead of trying to give the person something to eliminate the reaction, they are taking aim at the cat to decrease its amount of allergen, which is what causes allergies. You don’t react to cats, technically, but to their allergens.

And boy oh boy do some of us react to cats.

The point of the researchers’ focus is the Fel d 1 (not a typo) antigen, the allergen that is found mostly in cats’ tears and saliva. It is believed to be the instigator of most people’s allergic reaction to cats.

Can they make people who share their lives with cats less allergic?

If the Fel d 1 antigen is thought of as a lock, then the antibody against it can be thought of as the key. Each cat produces many Fel d 1 antigen ‘locks’ and each cat-allergic person produces many anti-Fel d 1 antibody ‘keys’ to fit each lock. Once one lock is occupied by one key, no other key can be there, hence a decrease in the Fel d 1 antigen locks that trigger cat allergies. In these instances, the person often produces an abundance of antibody keys, which show as cat-allergic symptoms such as watery, itchy eyes, sneezing, a runny nose, and a desire to run from the cat. The idea is to have the cat develop its own keys. These antibodies bind to Fel d 1, making a lock-and-key combination before the antigen lock has a chance to cause a reaction in humans. When the cat decreases the number of locks left unoccupied by keys, the allergic person’s body doesn’t have to produce so many keys, thus lowering the reaction that person has to the cat.

The first method being studied to decrease the amount of Fel d 1 antigen locks is a vaccine to be given to the cat. It is being developed in Switzerland by scientists at HypoPet. Results from their current study were released over the summer in The Journal of Allergy and Clinical Immunology. The results showed that after a series of vaccines, the cats being studied made their own antibodies against the Fel d 1 antigen, thus lowering the amount of antigen a human could be exposed to. Few side effects were reported in the cats, and those that were are on par with the mild side effects commonly seen with current vaccines.

Another important finding in this study was that the vaccine did not require an adjuvant to achieve a lowered amount of unbound Fel d 1. An adjuvant is a substance added to a vaccine that enhances the immune response to an antigen; it makes the vaccine stronger. Because of concerns with adjuvanted vaccines causing injection-induced cancer in cats, this is important to the cat’s health. As Martha Stewart might say, no adjuvant is a good thing.

On the sneezing human side, the binding of the Fel d 1 antigen and antibodies appears to work, decreasing human reaction to the antigen based on laboratory tests using blood from cat-allergic people. Further testing will be needed to see how long the vaccine’s effect lasts in cats and to make sure that there are no long-term unhappy effects in cats, as well as if vaccinated cats actually reduce reaction in allergic people.

The second method is being studied by Nestlé Purina PetCare and uses the cat’s food. The concept is similar: to have the cat develop its own antibodies against Fel d 1 so as to decrease the amount of allergens cat-allergic people are exposed to. In this instance, the stimulus to produce these antibodies is delivered in the cat’s food rather than with a vaccine. The initial results indicate a reduction in Fel d 1 allergens being left unbound. Fewer antigens means fewer reactions in people.

Unlike the results released for the vaccine, for this study using cat food there were no laboratory tests using cat-allergic people’s blood samples at this time. The study also does not discuss if the diet is tasty or has long-term effects for the cats, and it is unknown if the reduction in Fel d 1 allergens was enough to decrease or eliminate the allergic response in a human. One potential advantage of a food over a vaccine might be the ability to keep the level of antibody more consistent, but more research is needed.

With both methods, it is important to realize that these products are still in development and may not be available for years. It is also important to understand that while a given cat may be made less allergenic for a cat-allergic human, neither the vaccine nor the food is likely to work 100% in those cats that receive them, and they won’t work at all in cats that do not get them. An allergic person – or their partner or kids - may be more comfortable at home with their treated cats but may still have strong reactions when around other untreated cats.

Perhaps the biggest advantage will be for cats. Since human allergies are a common reason for cats to end up in animal shelters, these products may decrease that need. And if that happens, it would be nothing to sneeze at.