D3.349 - Evaluation of natural killer cells in female infertility

Increasing evidence suggests that the reproductive system is closely linked to the immune system. Natural killer (NK) cells are lymphocytes that play a crucial role in the innate immune system as a first line of defence and are believed to influence reproductive immunology significantly (Zhang & Wei, 2021). Finding more than 12% of NK cells in women experiencing infertility or recurrent miscarriages has been defined as elevated and is considered when planning treatment strategies (Luu et al., 2022). The aim of this study was to evaluate the results of clinical and immunological tests of women with suspected infertility of autoimmune origin.

A retrospective study was conducted, analysing data from females with suspected infertility of autoimmune origin between 2023 and 2024. Data collection included age, type of infertility, duration of infertility, and immunological indicators such as the concentration of antibodies to thyroid peroxidase (anti-TPO), antinuclear antibodies (ANA), and the number of NK cells in the lymphocyte population. The subjects were divided into two groups based on NK cell percentage: Group 1 - NK cells <12%, Group 2 - NK cells >12%.

A total of 43 women were examined, with an average age of 34 years (range: 26-44). The average duration of infertility was 5.49 (standard deviation (SD) - 4.07) years. Among the subjects, 40 (93.02%) presented with primary infertility, while 3 (6.98%) had secondary infertility. The average absolute NK cell count was 0.272 (SD 0.135) x10⁹/L, and the mean percentage of NK cells within the lymphocyte population was 14.37% (SD 6.488).

A positive ANA marker was found in 31 (72.09%) subjects. However, when comparing the two groups based on NK cell levels, no significant differences or associations were found between immune markers (ANA, anti-TPO) and other variables (age, type of infertility). The period of infertility was statistically significantly longer in Group 2 (5 years, range: 2-20) than in Group 1 (3.5 years, range: 1-12), p=0.024.

Female with NK cell counts above 12% had a longer duration of infertility period compared to those with lower NK cell counts. Still, the role of NK cell counts in female infertility risk needs further investigation in larger samples.