快猫短视频

A STRONG cup of coffee may help relieve hay fever, and might even be a
lifesaver for people who suffer potentially fatal reactions to nuts and bee
stings, say researchers in South Korea. They have found that in rats caffeine
can block acute allergic reactions such as anaphylactic shock.

Hay fever and asthma and similar allergies result from an oversensitive
immune system. In susceptible people, contact with substances such as pollen and
dust trigger a reaction from specialised mast cells, which release the chemical
histamine into affected tissues. It鈥檚 this histamine that produces the symptoms
familiar to allergy sufferers, such as swelling, itching and breathing
difficulties. Anaphylactic shock is a more severe life-threatening reaction that
can be triggered by compounds found in nuts and insect stings.

快猫短视频s already know that caffeine has anti-allergic properties, as it
cuts down histamine release from mast cells. But until now no one had tested its
effects on a full-blown allergic reaction. So Hyung-Min Kim and colleagues at
Wonkwang University in South Korea tried using caffeine to stop anaphylactic
shock in rats.

The researchers induced anaphylactic shock by injecting the rats with a
synthetic compound known as 48/80. This activates mast cells, eliciting a rapid
release of large amounts of histamine. In untreated rats, the injections caused
a fatal allergic reaction. But when the researchers repeated the trial with rats
given an infusion of caffeine, many survived.

Levels of caffeine as low as 0.1 milligrams per kilogram鈥攅quivalent to
someone drinking a single cup of coffee鈥攃ut the death rate by half.
Americans are estimated to consume, on average, two to three cups of coffee鈥檚
worth of caffeine a day.

Kim is hopeful that caffeine will have a similar effect in humans. 鈥淐affeine
may be effective in chronic allergic disorders,鈥� he says. And coffee could even
be useful in preventing everyday allergies, he believes. His group is currently
exploring how the drug acts on human mast cells.

Francesca Levi-Schaffer, a pharmacologist at the Hebrew University-Hadassah
Medical School in Israel, says that caffeine inhibits one of the enzymes
involved in histamine release in the same way as drugs used to treat asthma,
such as theophylline. Pharmaceuticals companies are interested in developing new
drugs that selectively interfere with this enzyme. 鈥淐affeine can be a
preventative drug if given by inhalation to asthmatic patients,鈥� says
Levi-Schaffer.

But Fred Pearce, a specialist in allergy research at University College
London, says that other drugs which inhibit mast cells may work better than
caffeine. And we don鈥檛 know whether the caffeine you consume when drinking tea
or coffee will have any effect on allergies, he adds. Unlike inhaled drugs used
to treat asthma, it is not targeted to the affected tissues. 鈥淵ou would need to
drink a lot of tea or coffee, with all the accompanying side effects, to get up
to meaningful levels,鈥� he says.