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 Researcher,
Dr Alex Taylor comments: ‘This molecule is like a living fossil - finding
out that it has an ancient past is like turning up a coelacanth in your garden
pond. By studying this molecule, we can track the evolution of allergic
reactions back to at least 160 million years ago and by looking at the
differences between the ancient and the modern antibodies we can begin to
understand how to design better drugs to stop allergic reactions in their
tracks.’
The chicken molecule, an antibody called IgY, looks remarkably similar to the
human antibody IgE. IgE is known to be involved in allergic reactions and
humans also have a counterpart antibody called IgG that helps to destroy
invading viruses and bacteria.
Scientists know that both IgE and IgG were present in mammals around 160 million
years ago because the corresponding genes are found in the recently published
platypus genome. However, in chickens there is no equivalent to IgG and so IgY
performs both functions.
Lead researcher, Dr Rosy Calvert explains: ‘Although these antibodies all
started from a common ancestor, for some reason humans have ended up with two
rather specialised antibodies, whereas chickens only have one that has a much
more general function.
‘We know that part of the problem with IgE in humans is that it binds
extremely tightly to white blood cells causing an over-reaction of the immune
system and so we wanted to find out whether IgY does the same thing.’
By examining how tightly IgY binds to white blood cells the researchers have
found that it behaves in a much more similar way to the human IgG, which is not
involved in allergic reactions and binds much less tightly
Brian Sutton, Professor of Molecular Biophysics in the Randall Division at
King's, where the research was carried out: ‘It might be that there was a
nasty bug or parasite around at the time that meant that humans needed a really
dramatic immune response and so there was pressure to evolve a tight binding
antibody like IgE.
‘The problem is that now we've ended up with an antibody that can tend to be
a little over enthusiastic and causes us problems with apparently innocuous
substances like pollen and peanuts, which can cause life-threatening allergic
conditions.’
The next stage of the work is to examine in very fine detail the interaction
between the antibodies and the surface of the white blood cell. This is with a
view to designing drugs that could alter this interaction and therefore 'loosen'
the binding of IgE, making it more like its chicken counterpart.
Notes to editors
King's College London
King's College London is one of the top 25 universities in the world (Times
Higher 2007) and the fourth oldest in England. A research-led university
based in the heart of London, King's has 19,300 students from more than 130
countries, and 5,000 employees. King's has an outstanding reputation for
providing world-class teaching and cutting-edge research. The College is in the
top group of UK universities for research earnings and has an annual income of
approximately £400 million. An investment of £500 million has been made in the
redevelopment of its estate.
King's has a particularly distinguished reputation in the humanities, law,
social sciences, the health sciences, natural sciences and engineering, and has
played a major role in many of the advances that have shaped modern life, such
as the discovery of the structure of DNA. It is the largest centre for the
education of healthcare professionals in Europe and is home to five Medical
Research Council Centres – more than any other university.
King's College London and Guy's and St Thomas', King's College Hospital and
South London and Maudsley NHS Foundation Trusts are working together to create
the UK's largest Academic Health Science Centre (AHSC). The AHSC will bring
together the widest range of clinical and research expertise in the UK –
strengths that will be used to drive improvements in care for patients, allowing
them to benefit from breakthroughs in medical science and receive leading edge
treatment at the earliest possible opportunity.
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