[tri-med] FYI - Children 2 to 4 Years Old Can Lose Antigen-specific IgE to Aeroallergens

Sorry Michelle :-)
****I am forwarding this article or URL for your information (FYI) as I
believe it may be of interest and is from a reliable source. As always,
check the information with your own doctor or health care professional
before starting or changing any treatments.****
http://www.docguide.com/news/content.nsf/news/8525697700573E1885256E61007DCE4C?OpenDocument&id=15A05DF341D10BA2852568E4007B3C1F&c=&count=10
AAAAI: Children 2 to 4 Years Old Can Lose Antigen-specific IgE to Aeroallergens
By Paula Moyer

SAN FRANCISCO, CA -- March 24, 2004 -- Young children who are initially 
sensitised to an aeroallergen can lose that sensitivity in a 2-year time 
period, and are more likely to do so if the family acquires a dog, according to 
findings presented here March 21st at the American Academy of Allergy, Asthma, 
and Immunology's 60th Annual Meeting.

This finding is contrary to the common assumption that young children's 
aeroallergen sensitisation is persistent, said principal investigator Michael 
R. Simon, MD.

"We have thought that, if a 2-year-old child had developed an allergy to an 
air-borne substance, that the child would continue to be allergic," said Dr. 
Simon, Professor of Paediatrics and Internal Medicine, Wayne State University, 
Detroit, Michigan, United States. "We wanted to test the validity of this 
assumption after 2 European studies had shown that school-age children can lose 
their allergies, and that exposure to farm animals increases the likelihood of 
this happening."

He and his co-investigators obtained data on children who were enrolled in the 
Childhood Allergy Study in suburban southeast Michigan. The children were 
tested for the presence of immunoglobulin E (IgE) that was specific to 
Dermatophagoides farinae, D. pteronyssinus, dog, cat, short ragweed, and 
timothy grass. The investigators defined a child as sensitised if there were 
measurable aeroallergen-specific circulating IgE to any of these 6 
aeroallergens in a blood sample.

Among the 339 children who were tested at ages 2 and 4 years, 48.7% initially 
had at least 1 positive allergen-specific IgE test. At age 4 years, 37% who had 
had a positive test became negative to all tests upon retesting. Among these 
children, 104 were positive at both testing times, and 109 were negative on 
both occasions. Among the 174 children who were initially negative, 37% became 
positive at the second testing period.

Among the 165 children who were initially sensitised, the families of 25 
acquired a dog; 139 had no dogs, and the pet status of 1 child was unknown. 
Among the 139 with no dog, 14.4% lost their sensitivity to all tested 
allergens. Among the 25 with a dog, 40.0% lost their sensitivities. Removing an 
animal from the home had no effect on sensitivities, Dr. Simon said.

These findings should not suggest that a child who is allergic to dogs and has 
allergy symptoms in the presence of a dog should acquire one, he stressed.

"An individual who has a symptomatic allergy to dogs and is exposed to a dog 
will have increased symptoms," he said. "For people with allergy symptoms, the 
source of the allergen should still be removed from the house."

He added that the reason for dogs' protective effect is unknown, but thought to 
be related to the introduction of canine endotoxins to the immune system.

"Our results have significant implications for assessing allergy in young 
children over time, as well as for the study of the immunological effects of 
allergen-injection immunotherapy," he said.


[Study Title: Loss Of Antigen-Specific IgE to Aeroallergens in Children Between 
Ages Two and Four Years. Abstract 463] 


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