PROBLEM: An increase in natural killer (NK)-cell activity has been observed
in women with unexplained recurrent miscarriages. Because of the many simi
larities between infertility and early pregnancy loss patients, we investig
ated whether infertile women had raised NK-cell activity.
METHOD OF STUDY: We tested 94 infertile women who, in spite of treatment, w
ere unable to conceive for 6 or more months. NK-cell activity was measured
by using a chromium-51 release cytotoxicity assay, with K562 human myeloid
leukemia cells as targets.
RESULTS: NK-cell activity of the infertile group (mean +/- SD; 40.2% +/- 14
.7) was significantly higher than the control group (31.5% +/- 11.9, P < 0.
0001). The increased NK-cell activity was not associated with age, infertil
e duration, depression scores, treated hyperprolactinemia, or treated endom
CONCLUSIONS: In certain patients, elevated NK-cell activity may be consider
ed an independent risk factor for infertility.