DRUGS that suppress the immune system hold out new hope for thousands of
women with infertility problems.
Alan Beer of the University of Chicago studied women with unexplained
infertility who had suffered repeated miscarriages after IVF treatment. He found
that 70 per cent of women with three IVF failures had higher than usual levels
of an immune-system chemical called tumour necrosis factor alpha. TNF-alpha is
involved in producing inflammation, and raised levels are found in people with
autoimmune diseases such as multiple sclerosis and rheumatoid arthritis.
Suspecting that too much TNF-alpha might encourage the immune system to
attack the developing embryo, Beer gave drugs that reduce levels of the chemical
to 100 women with fertility problems. When they tried IVF again, nearly 80 per
cent of those under 35 and 60 per cent of those aged 42 or more became pregnant,
he told a meeting of the British Fertility Society in Nottingham this week.
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Beer’s success rates are “astonishing” for women who would otherwise be very
unlikely to become pregnant, says Simon Thornton of the CARE fertility clinic at
the Park Hospital in Nottingham. He suggests that simply reducing TNF-alpha
levels might be an alternative to IVF for some women who have unexplained
infertility.
How the immune system is prevented from attacking the fetus is still poorly
understood (Inside Science, 91av, 15 September 2001). Last year, a team
at the US National Institutes of Health found that a hormone produced by the
uterus wall and the developing embryo can trigger active killer T cells to
commit suicide. Unusually low levels of this hormone may also cause
miscarriages.