It would be helpful if immunologists and epidemiologists were able to tease out each factor contributing to the escalation of allergies and say, J'accuse! That's probably not going to happen. Instead, researchers are attacking the problem on all fronts. Their unspoken attitude? We've made a mess of this planet, and we may not be able to ﬁx it. The best science can do is help us ﬁx ourselves.
Since most of us are unable to room with a pig, we have to come up with a plan. Can we avoid allergies altogether? Can we get rid of allergies we already have? Can we desensitize our immune systems?
"We still don't know exactly how to prevent allergies," says Andrew Liu. "We know the immune response is supposed to be a helpful one, that it's not supposed to be the cause of disease. We know that the immune system of someone with allergies needs to be reeducated. But how? It's not always clear."
Leung agrees, adding, "If you are exposed to endotoxin or other microbial products early in life, it may prevent allergies. But later in life the early exposure may actually make things worse." There are those who argue that to prevent allergies, we should reduce or eliminate exposure to harmful allergens at an early age. Others believe allergens should be administered in large quantities at an early age. Many believe it depends on the speciﬁc allergen. And food allergies may work on an altogether different principle. Confused? So are the allergists.
Improvements in immunotherapy have been hard to come by. The overall idea behind immunotherapy is to ﬁnd something that alters the T-cell reaction to the allergen to one not associated with allergic symptoms when the allergen is reintroduced. Currently, the best method is to have injections containing increasingly larger quantities of the offending substance every week for three to ﬁve years. "It requires time, investment, and money," says Harold Nelson.
At Johns Hopkins School of Medicine's Asthma and Allergy Center, clinical director Peter Socrates Creticos is studying what is essentially a ragweed vaccine. The vaccine contains the principal offending allergen from ragweed along with bits of DNA. The DNA acts as an adjuvant that allows the body to recognize the allergen more efﬁciently and begin a string of cellular events in the immune system that shuts down chronic inflammation.
Best of all, Creticos notes, "Just six weeks of injections before ragweed season caused people to experience 70 percent fewer symptoms. That's about the same degree of improvement we normally see with the earlier therapy after three years," he says. Better yet, the effects of the vaccine carried over to the next ragweed season. "We didn't just reduce symptoms," Creticos says, "we turned off the disease."