Despite their name, natural killer cells are not the enemy. They are an essential part of the immune system. There are a variety of natural killer cells, dependent on where they are in the body and their molecular make-up. Slight molecular variations can make a big difference in how the cells act in the body.

Natural killer cells (NK cells) play an essential role in in helping the body fight infection or invasion. NK cells are distributed widely in all tissues, but are especially concentrated in the uterus. In some people, the immune system mistakenly recognises and attacks ‘self’. Women who have fertility problems, specifically miscarriage or embryo implantation failure, are more likely to have higher levels of activity of these natural killer cells. Uterine NK cell numbers increase enormously from less than 10% before conception to 30% in early pregnancy.

Successful pregnancy may require a significant modification of the mother’s immune system to prevent it from ‘rejecting’ the embryo. Whilst the embryo shares some of the mother’s genes, it also has its own which means it is seen as a ‘foreign body’ by the mother’s immune system. Women with raised NK cell activity in their blood have about a four-fold increase risk of miscarriage with karyotypically normal foetuses. In early pregnancy (including after IVF), lower blood levels of NK cell cytotoxicity are significantly associated with livebirth.

In Australia, Dr Gavins Sacks from IVF Australia has pioneered the development of natural killer (NK) cell tests in Australia. NK cells are the main immune cells in the womb at the time of implantation, and may be a marker for immune implantation problems.

The NK cell test

The NK cell tests can be done by blood test or womb biopsy. At Darling Health we have the ability to test the NK cells via blood through our affiliates. A referral from your doctor may also be required and the taking of blood is through specific pathology clinics.

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