The Assessment of NK Cytotoxicity and CD56+/CD16+ Phenotype by Flowcytometry in PBL Isolated from Women with Recurrent Spontaneous Abortion

Background: Human peripheral blood NK cells constitutively express CD56 and CD16 antigens. Peripheral blood NK cells seem to be strongly related with decidual NK cells, and may reflect the decidual NK cell functional status. There are varied reports concerning the relationship between NK cell cytotoxicity in women with recurrent spontaneous abortion. Objective: To study NK activity in women with history of RSA by using a non-radioactive cytotoxicity assay. Methods: Peripheral blood lymphocytes from RSA and healthy multiparous women were obtained. Lymphocytes were isolated and mixed with K562 NK-sensitive cell line. A non-radioactive method for NK cell cytotoxicity assessment was utilized. Dead K562 cell populations were detected by FACS Calibur flow cytometry, and the data obtained was analysed on cell-Quest software. The proportion of CD16+ /CD56+ cells was then calculated. Results: The proportion of NK cells were 9.21% ± 3.06 and 13.48% ± 4.09 in healthy women and RSA, respectively. The percentage of cytotoxicity was determined to be 19.3% ± 3.9 in healthy group and 27.1% ± 6.5 in RSA group with an effector:target ratio of 50:1. The data shows an increase in PBLs potential for in vitro cytotoxicity assay in RSA individuals. The analyses indicate that there is a weak positive correlation between NK cytotoxicity potential and the percentage of NK cells in PBL population. Conclusion: The present study demonstrates that the percentage of CD56+ /CD16+ cells increases in individuals with recurrent spontaneous abortion. We conclude that NK cytotoxicity as well as NK number is partially involved in RSA.