Berlin (dpa) - All that glitters is not gold - as everyone knows
who gets a rash from cheap jewellery - and now German scientists have
proven that there is such a thing as being allergic to costume
jewellery.
Nobody owns "pure gold" jewellery - unless your name happens to be
Tutankhamun. All modern-day "solid gold" jewellery is in fact an
alloy of gold mixed with baser metals such as copper and nickel. The
"carat" designation indicates the amount of gold. The higher the
carat number, the more gold and less base metal there is in the piece
of jewellery - and the higher the price.
In the past, it was generally assumed that the negligible amounts
of base metals in "solid gold" jewellery could not possibly result in
an allergic skin reaction. The new findings show that you can indeed
be allergic to cheap jewellery.
For many people, wearing a pair of alloy earrings can produce a
painful red swelling and blisters. Coins, belt buckles, and even
mobile phones may also cause an unpleasant allergic reaction when
they rub against the skin.
The reason is that they all contain nickel, the most common cause
of skin contact allergies in the industrialised world. But few people
realize that nickel is commonly used to make "gold" jewellery.
The researchers, led by Dr Matthias Goebeler from the University
of Giessen in Germany, have shown that nickel binds to a particular
immune-system protein normally involved in detecting harmful
invaders. In susceptible people, this results in the body recognising
nickel as an infectious agent and triggering inflammation.
As the immune system goes into overdrive, it produces the classic
symptoms of burning, itching, redness, swelling and blisters.
The scientists studied the nickel-immune response in genetically
engineered mice. Only animals capable of producing the human protein
TLR4 (toll-like receptor 4), developed "contact hypersensitivity"
(CHS) when exposed to nickel.
Human TLR4 acts like a "switch" that triggers a cascade of
biochemical reactions when certain substances bind to it. The
molecular signals it gives off result in the increased blood flow,
leaky tissue, and influx of immune-system cells that give rise to
inflammation.
Although the reaction is due to the body defending itself, it
often has undesirable side effects.
The scientists outline their findings in the journal Nature
Immunology. Drugs that block specific TLR4 binding sites could
provide a way of treating nickel allergy, the researchers suggest.
"Our data implicate site-specific human TLR4 inhibition as a
potential strategy for therapeutic intervention in CHS that would not
affect vital immune responses," the scientists wrote.
In Europe alone, an estimated 65 million people are sensitised to
nickel and develop contact dermatitis when atoms of the metal touch
their skin.
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