Timed sexual intercourse facilitates the recruitment of uterine CD56(bright) natural killer cells in women with infertility.

PROBLEM: The aim of this study was to investigate the influence of sexual intercourse on uterine NK cell subsets.

METHOD OF STUDY: Mid-secretory endometrial samples obtained from 56 women were submitted for flow cytometric analysis. Basal body temperature was used to determine the day of ovulation. A total of 27 women had sexual intercourse before ovulation (pre-ovulation group) and eight women had only after ovulation (post-ovulation group) without any contraceptive devices. A total of 21 women did not have sexual intercourse during the experimental cycle (abstinence group). Endometrial NK cells were analyzed for the expression of CD16 and CD56 using 3-color flow cytometry.

RESULTS: CD16(-)/CD56(bright) cells were markedly increased in the pre-ovulation group as compared with that of the post-ovulation group (P < 0.01) and the abstinence group (P < 0.01). CD16(+)/CD56(dim) cells were significantly decreased in the pre-ovulation group as compared with that of the post-ovulation group (P < 0.01) and the abstinence group (P < 0.05).

CONCLUSION: It is suggested that seminal plasma participates in the recruitment of CD56(bright) NK cells into endometrium.