Residues of Fossil
Increase Allergic Responses
UCLA researchers have joined the effort to establish a connection
between the residues of fossil fuel combustion [aromatic hydrocarbons,
such as the propellant solvent xylene which, according to the label,
composed at least half of the Diazinon formulation used on the
SBU campus] and an epidemic of respiratory allergies.
Two centuries ago, "airway" diseases such as hay fever and allergic
asthma were rare and mostly minor afflictions. Today, according to
Dr. Andrew Saxon, chief of the UCLA School of Medicines Division
of Clinical Immunology and Allergy, approximately 40 percent of the
worlds population is at risk. And, despite vastly improved knowledge
of the pathophysiology and treatment of allergic asthma, that condition
is not only more common, but also more severe than ever before.
Intrigued by the history of the epidemic, Saxon and colleagues
(Drs. Oliver Hankinson, Harvey Herschman and André Nel) at the
UCLA Asthma, Allergy and Immunologic Disease Center began
looking at possible underlying causes.
"Human genetics have changed trivially over 200 years," says Saxon.
"The plants in our environment are not that different. The major change
has been industrialization." In particular, the researchers were interested
in studies conducted in Japan suggesting that materials from fossil
fuel combustion could affect the mucous membranes in the lungs and
nose, boosting an allergic response. "We decided that if this were true,
it would be very important to bring molecular immunology, molecular
biology and molecular genetics to bear on the issue," Saxon says.
Saxon, whose own background is in research on the structure of the
genes that make the proteins that cause allergies in humans, began
to study the impact of airborne pollutants on these genes as a way
of accounting for the increasing incidence and severity of asthma.
He chose to focus on diesel exhaust particles, not because he thought
it likely that they were the only culprit (although as less coal is burned,
they are, in fact, an increasingly important source of airborne particulates),
but because diesel exhaust can be measured in the environment
and reproduced in a laboratory setting. Diesel and other fossil fuel
combustion products, known as xenobiotics, carry chemicals which,
once inside the airway, penetrate the cell membrane and attach to a
special aromatic hydrocarbon receptor, which is involved in breaking
down such materials.
Saxon hypothesized that this process stimulates the immune system
so that, in the presence of these chemicals, an antigen that the body
might otherwise ignore triggers an allergic response.
In studies that began in the test tube and eventually involved volunteer
human subjects, Saxon found that among individuals who were sensitive
to a particular allergen, instilling the allergen, plus diesel exhaust particles,
in the nose in doses equivalent to breathing the air in Los Angeles for
one to three days produced a fivefold increase in total allergic protein
level and a 50 fold increase in the number of reaction inducing allergic
For the information on the complete research study, please see
the complete article at the Research@UCLA Website.
For more information on the Aromatic Hydrocarbons such as
the xylene used on the SBU campus, please see the Aromatic
Hydrocarbon and Other Toxic Solvents Information Page.
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