March 21, 2005 08:41:13 PM PST
By Amanda Gardner
HealthDay Reporter

MONDAY, March 21 (HealthDay News) -- Scientists have found significant
differences in a blood marker for allergies between parents and their
children, indicating that kids today may be more subsceptible to
allergies than previous generations were.

This appears to be the first quantitative, objective evidence that
allergies and asthma are on the rise in the world today.

The findings were presented Monday at the annual meeting of the
American Academy of Allergy, Asthma and Immunology (AAAAI) in San
Antonio.

Although there have been numerous reports that allergies and allergic
disease such as asthma are on the rise, most of the evidence so far has
been anecdotal, said Brock Williams, the author of the study and a
clinical professor of allergy immunology at Children's Mercy Hospital
in Olathe, Kan.

To see if there might be any objective evidence for these claims,
Williams and his colleagues tested IgE levels in 1,481 people -- 667
parents and 804 children. At least one parent in each family had to
have asthma.

"IgE is the factor in the blood that is responsible for producing
symptoms of allergies," Williams explained. "An increase in allergy and
asthma should be reflected in IgE levels."

As it turned out, children had IgE levels at a minimum of four or five
times higher than their parents. The children also had higher IgE
levels for specific allergens: 45.3 percent of parents and 60.1 percent
of their children had IgE readings for dust mites. Levels were also
elevated, although not as sharply, for cat and mold.

"It looks like the increase in asthma and in allergic disease could
actually be due to increased sensitization to mites," Williams said.
Dust mites are fairly ubiquitous, except in high, dry locations such as
Denver, where last year's AAAAI meeting was held.

"There are more dust mites in San Antonio than Denver," said Dr.
Kathleen Sheerin, public education chair of the AAAAI and moderator of
the news conference. "We're suffering this year."

There are several hypotheses explaining the increase but no sure
answer.

It's "fairly plausible that we've made it happier for mites to live in
our indoor environments," Williams said. "We spend more time indoors.
Kids spend more time indoors. We have regulated temperature. We feed
them pretty well because they eat skin scales from humans."

Children are also treated today for infectious illnesses, which might
mean they don't build up their immune systems enough, although Williams
was quick to emphasize he did not advocate not treating kids for
infections.

In other presentations Monday, two studies looked at the link between
obesity and allergies in children. Both conditions are on the rise in
children, as well as adults.

Dr. Kentaro Matsuda, assistant professor of pediatrics at Kurume
University School of Medicine in Fukuoka, Japan, found that obese
children had significantly higher IgE levels than normal-weight
children. His study involved 49 obese children and 49 children who
served as controls. The elevated IgE levels did not seem to be related
to allergic disorders, but there was as correlation between IgE levels
and leptin levels. Leptin is a hormone that regulates appetite, which
may start to explain a link between obesity, allergies and future
development of asthma.

Obesity has been associated with respiratory problems in older people.
A second study wanted to see if there were differences in asthma
severity and air flow between obese asthmatic children and their normal
weight asthmatic counterparts.

The researchers looked at the charts of 278 children aged 5 to 20
years. Forty percent of the children were normal weight, 41 percent
were obese, 17 percent were overweight and 2 percent were underweight.

Obese children did not have more severe asthma, said Dr. Sitesh Roy,
assistant professor of pediatrics at the University of Mississippi in
Jackson. Nor did they have a reduced level of asthma control. There
was, however, a slight reduction in the FEV1/FVC ratio, a measure of
airflow obstruction.

"The difference was small and still in the mild-to-minimal obstructive
range, but this still could be a very valid finding," Roy said. "This
may indicate some degree of increased airway inflammation, but it also
could be a more mechanical factor."