NEW YORK, Jun 07 (Reuters Health) - Children who are at risk for asthma
because of a family history of allergies may be more likely to develop the
respiratory disorder if they are exposed to cockroaches in early infancy,
according to a recent report.
The study findings show that those newborns who live in homes where
cockroach allergen (allergy-inducing protein) is present are more likely to have
activated T lymphocytes--cells that contribute to inflammation--by age 2.
While the study did not look specifically at children who developed asthma,
such activated T lymphocytes play a key role in allergies and the underlying
lung inflammation that can cause asthma. If researchers can determine exactly
how certain allergens contribute to asthma, it may be possible to find ways to
help prevent the respiratory disorder.
"Recent studies suggest that most asthmatic patients are diagnosed by the
age of 6 years, with symptoms first occurring during infancy and early
childhood," write Dr. Patricia W. Finn from Brigham and Women's Hospital in
Boston, Massachusetts, and colleagues.
The study authors note that more than 80% of children with asthma have one
or more allergies.
To investigate environmental factors that may play a role in allergic
asthma, the team of researchers looked at the relationship between allergens
from cockroaches, cats and dust mites at 3 months of age, and levels of
activated T lymphocytes at age 2. Such cells will proliferate in the presence of
an allergen, releasing growth factors and triggering the production of proteins
that contribute to inflammation.
The investigators collected dust samples from the homes of 114 families in
which a parent had a history of asthma or allergies. Allergen levels were
measured when the child was 3 months old. Over the next 2 years, the researchers
interviewed parents about changes in the child's health and various features of
the home.
The authors report, in a recent issue of the Journal of Allergy and Clinical
Immunology, that exposure to cockroach allergen is associated with an increase
in these cells over 2 years.
"Taken together, our data indicate that early-life...exposure to cockroach
allergen predicts later lymphocyte responses," Finn and colleagues conclude.
"T-lymphocyte activation is critical to the induction of an allergic response."
