Association between chronic endometritis and uterine natural killer cell density in women with recurrent miscarriage: clinical implications

Abstract

Aim: This aim of this study was to determine the association between uterine natural killer (uNK) cell density and chronic endometritis (CE).

Methods: Endometrial biopsies from 135 women with recurrent miscarriage were obtained precisely 7 days after luteinizing hormone surge in natural cycles. Endometrial sections were immunostained for CD56 for uNK cells and CD138 for plasma cells, respectively. Uterine NK cell counting was performed according to a standardized protocol and results were expressed as percentage of CD56+ cells/ total stromal cells. High uNK cell density was defined as >4.5% and CE was diagnosed when the plasma cell density > 5.15 cells/ 10 mm² .

Results: The uNK cells density in women with CE (median, 5.1%; range, 3.4-8.8%) was significantly (P < 0.05) higher than that of those without CE (median, 3.8%; range, 1.2%-7.3%). The prevalence of high uNK cell density in women with CE (11/29, 37.9%) was significantly (P < 0.05) higher than that of women without CE (8/106, 7.5%).

Conclusion: To conclude, there was a significant association between high uNK cell density and CE. In women with high uNK cell density, plasma cell should be examined to determine if the underlying cause is associated with CE.

Keywords: chronic endometritis; investigations; plasma cell; recurrent miscarriage; uterine natural killer (uNK) cells.