Study Sheds New Light on Cow’s Milk Allergy
Cow’s milk allergy (CMA) affects 2-3% of infants. Why do many of these children outgrow the condition by school age, while others do not? To find the answers, researchers at Mount Sinai School of Medicine (New York, NY) and Finland’s University of Helsinki explored the complex interaction between cow’s milk proteins and the different types of antibodies that bind to them. The results of this FAI-funded study were published in the June 2010 issue of the Journal of Allergy and Clinical Immunology.
A food allergy results when IgE, a type of antibody whose primary role is to fight parasitic infections, mistakenly targets a harmless food as a dangerous invader. When you eat the problem food—in this case, dairy products—IgE antibodies bind to tiny fragments of the food proteins, triggering the release of histamine and other chemicals that cause an allergic reaction. But what role might other antibodies play in promoting tolerance to cow’s milk over time? Previous research has indicated that two antibodies, IgA and IgG4, appear to contribute to the development and maintenance of tolerance to various foods.
Over several years, the research team, led by Hugh Sampson, MD, of Mount Sinai, tracked 23 patients who were diagnosed with CMA as infants. Eleven still had CMA at age eight or nine, while 12 had outgrown their allergy by the time they were three years old. Using serum samples from these patients, the researchers examined the pattern of binding between five major cow’s milk proteins and three antibodies, IgE, IgA, and IgG4.
They found that:
- Over time, IgE binding patterns remained stable in patients who had persistent CMA. Conversely, IgE binding decreased in children who outgrew their allergy early.
- In children who recovered early, IgG4 binding gradually increased as IgE binding decreased.
The researchers concluded that these findings may help predict whether or not a child is likely to outgrow CMA early, and could lead to the development of new immunotherapies for CMA.