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Unexplained Infertility And Natural Killer Cells

Could an over-zealous immune system be at the root of your unexplained infertility? Could the same helpful cells that protect you from foreign viruses and errant cancer cells be making your uterus inhospitable to a new and *foreign* embryo too?

A 2011 study from Argentina has uncovered a possible cause of unexplained infertility that many have long suspected but few have researched. The researchers of this study purport that once the usual suspects have been ruled out, some 80% of unexplained reproductive failure is thought to be related to immune system imbalances, specifically natural killer cell (NK) problems.

The researchers sought to explore the commonly held belief that imbalances between cytokines and endometrial natural killer cells (NK) at implantation time could be a cause of repeated implantation failure. They measured NK cells, regulatory cytokines - which control inflammation - and VEGF, a growth factor which is important for implantation.

The study group comprised twenty seven women with unexplained infertility and implantation failure, and fourteen healthy controls; samples of endometrial tissue and blood were taken at implantation time - 5-8 days after ovulation - for analysis. The study found that women with unexplained infertility and implantation failure had significantly higher levels of cytoxic NK cells in their endometrial tissue samples and lower levels of IL-6 and VEGF when compared with the control group. The researchers concluded that:

"Unexplained infertility is associated with exacerbated cytotoxic NK cell levels and endometrial IL-6 deficiency measured during implantation window."

"These immunological markers have good diagnostic ability, and could be used as criterion for therapeutical decisions."

Such immune dysfunctions are usually the domain of reproductive immunologists rather than reproductive endocrinologists. Because most women with unexplained infertility consult with reproductive endocrinologists as their primary infertility specialist women with unexplained infertility are often not screened for this possible cause of their fertility problems.

Natural killer cell levels in peripheral blood samples are routinely checked by reproductive immunologists and have been shown in other studies to correspond with the levels of natural killer cells within the uterus. This study however did not find a correlation between blood levels and uterine levels of NK cells.

If you discover that you have a problem with your NK cells you may want to check out intralipids as a possible treatment, studies show that it reduces NK cell levels and may help you to conceive. Some studies show that having high levels of NK cells can impair the blood flow to the uterus also which you may want to explore with a reproductive practitioner who is familiar with measuring and treating endometrial blood flow impairments.

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1. Fertility and Sterility P-129 Tuesday, October 18, 2011
PLANTATION FAILURE. A. Pasqualini, G. Junovich, A. Azpiroz,
C. Lucini, E. Incera, G. Gutierrez. Halitus Medical Institute, Capital Federal,
Buenos Aires, Argentina.

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