Asthma and the Allergic March Re-visited

Pediatricians that refer patients to me are more often screening children for allergic sensitivity within their first few years of life. Most often they order a special blood test for IgE. IgE is an antibody which is specifically made by certain white blood cells in our body. IgE is a Y shaped protein which is able to specifically recognize allergen triggers. The IgE antibody circulates in the blood and makes its way into surrounding tissue where mast cells are located. The mast cells hang out in areas under the skin, inner surface of the nose, eyes, lungs, inner ear, stomach and intestines. The IgE antibodies are able to attach to the surface of mast cells and behave like tiny antennas. When they come in contact with an allergen particle they [IgE] send a signal to the mast cell to release histamine and other substances that initiate an allergic response:

          Nose: itching, runny nose, sneezing and nasal congestion

          Eyes: watering, itching, burning, redness

          Lungs: wheezing, cough, chest tightness, shortness of breath

          Stomach/intestines: cramping, abdominal pain, diarrhea

          Skin: itching, hives, eczema

Atopic or Allergic diseasesare caused by the generation of IgE antibodies to particles that are commonly located in the environment (dust mite, pollens, mold spores, animal dander and insect proteins). Everyone doesn’t over-produce these IgE antibodies, just those who suffer from allergy problems (more than 50 million people in the U.S.).

I have previously discussed the “Atopic March” but some major points warrant review.

Long term studies following children with early eczema and/or wheezing (eczema or wheezing before 3 years of age) have greatly improved the ability to predict the development of asthma.

Major factors include the presence of eczema, parental history of asthma and documented allergy to an environmental allergen (pollen, mold, dust mite, cockroach or pet). Minor factors associated with the development of asthma include: documented allergy to food, elevated blood eosinophil number or wheezing apart from of having a cold.

 Having one of the major factors along with two of three possible minor factors means there is a greater than 70% likelihood of asthma development. This API does not reflect on the likelihood of adult onset asthma, only the development of childhood asthma.

The Allergic March describes the tendency to early on develop eczema followed by allergic nasal symptoms and subsequently asthma. Understanding the sequence of events that begin within the first few years of life is crucial to the development of treatment that may prevent asthma.

To date, allergy immunotherapy (allergy shots) is the only treatment that may potentially modify the course of the Allergic March. The problem is young children under 5 years of age would likely be the prime target to prevent asthma. Generally, allergists wait until school age to start allergy shots, primarily out of concern over the associated patient (and parent) emotional impact of getting weekly injections.

Perhaps this is why sublingual immunotherapy (allergy desensitization by placing drops under the tongue) may be more useful in the future when it becomes more standardized and FDA approved. Until then, comprehensive allergy management, utilizing environmental controls for allergy trigger avoidance, prescribed medications and allergy shots where indicated will continue to be the mainstay of asthma treatment.

Want to learn more? See:  All About the Allergic March