Natural killer cells play role in recurrent miscarriage
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11 September 2013, 6.04pm BST
Natural killer cells play role in
recurrent miscarriage
A U TH O R
Jo Adetunji
Editor, Health & Medicine, The
Conversation
I N T E RV I E WE D
Siobhan Quenby
Professor of Obstetrics at
University of Warwick
Nick Macklon
Professor of Obstetrics and
Gynaecology at University of
Southampton
Recurrent miscarriage can be devastating. Kouk
The Conversation is funded by the
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Caledonian, Liverpool, Open, Salford,
Sheffield, Surrey, UCL and Warwick.
It also receives funding from: Hefce,
Hefcw, SFC, RCUK, The Nuffield Foundation
and The Wellcome Trust
Suffering a miscarriage can be a very distressing experience
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More frustrating still is that in many cases – more than half –
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doctors are unable to find an underlying cause or offer more
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but for many women their next pregnancy is a normal one.
For women, however, who suffer recurrent miscarriage, where
they have three or more in a row, it can be utterly devastating.
than just a handful of options for treatment.
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Now researchers from Warwick University claim to have made
a breakthrough. Not only by making a firmer case for the role
TA GS
of natural killer (NK) immune cells in some cases of recurrent
Fertility, Pregnancy
miscarriage, but also in bridging the gap between scientists
and the medical profession in what has become a
R E LA TED ARTICLES
controversial area of research.
27 August 2013
Despite their name, NK cells actually play a beneficial role in
Epilepsy drug causes birth
defects – depending
on dose
the development of an embryo. But abnormally high levels of
NK cells are found in the uterus of some women (around a
http://theconversation.com/natural-killer-cells-play-role-in-recurrent-miscarriage-18126[12/09/2013 10:18:34]
19 August 2013
Natural killer cells play role in recurrent miscarriage
sixth) who recurrently miscarry. NK cells are a key player in
Anxiety may start in
the womb
the innate immune system, which can be triggered to defend
the body from infection. One theory is that in some cases they
may stop an embryo implanting in the womb.
7 August 2013
Oral antioxidants do not
assist conception
However, little is known about this mechanism. And the
potential role that NK cells might play in recurrent miscarriage
has caused significant controversy.
The authors of the new study, published in The Journal of
Clinical Endocrinology & Metabolism, make a link between
more NK cells in the lining of the womb and a deficient
6 August 2013
production of natural steroids. Having this deficiency in turn
leads to a reduction in the formation of fats and vitamins that
Effects of prenatal stress
can affect children
into adulthood
provide essential nutrition during pregnancy. They suggest
that NK cells can be used as an indicator of steroid
29 July 2013
deficiency.
Fish oil could help avoid
pregnancy complications
Steroids, which are thought to work by reducing the
percentage of NK cells in the womb, are commonly used as a
treatment for recurrent miscarriage and do appear to help
some women to go on to have a normal pregnancy. But many
experts agree this is based more on empirical evidence that a
firm scientific understanding.
Siobhan Quenby, Professor of Obstetrics at Warwick Medical
School and one of the authors of the study, said treatments
for recurrent miscarriage often came “out of guesswork, not
science” and said the research provided an “excellent
scientific justification for steroid-based treatment to prevent
miscarriage.”
“If you have NK cells in the blood they do things like fight
infection. In the uterus they also have a good function – for
example they help in the development of the blood supply to
the foetus.
“But we now have some light at the end of the tunnel; in
some ways everyone is right. NK cells are good but high end
NK cells are also associated with local steroid deficiency.”
Quenby said that the research suggests the deficiency causes
an increase in the higher percentage of NK cells, rather than
the other way round.
Nick Macklon, Professor of Obstetrics and Gynaecology at
Southampton University and an expert in IVF, said: “The
problem is that we haven’t really understood the mechanisms
http://theconversation.com/natural-killer-cells-play-role-in-recurrent-miscarriage-18126[12/09/2013 10:18:34]
Natural killer cells play role in recurrent miscarriage
behind recurrent miscarriage. We now know that an important
determinant is the lining of the womb and how it helps
embryos to implant. A lot of treatment has been empirical,
adopting theoretical treatments not on the science.
“Quenby has done a lot of work to try and understand the role
of NK cells, which hasn’t been very clear. The key thing is
that the researchers aren’t saying they are bad but when
there’s an increase it might be a useful marker. It could allow
for treatment to be rationalised. Steroids have side effects and
have been used very blindly. But they do seem to make a
difference and also to the needs of doctors and patients
looking for help.”
Macklon said recurrent miscarriage was probably caused by a
number of different factors across different cases. “One
possible cause is the ability of the lining of the womb to
recognise and select good embryos and in some women it
isn’t able to do this early enough.”
A previous small randomised trial carried out by Quenby
showed a marked difference in the chances of going on to
have a baby in a group of 20 women treated with steroids
versus an identical sized group given placebos. But she
admits that to draw solid conclusions, a trial size of around
700 women is needed.
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http://theconversation.com/natural-killer-cells-play-role-in-recurrent-miscarriage-18126[12/09/2013 10:18:34]