Decidual CD56+ Natural Killer Cells in Spontaneous Early Pregnancy Loss- An Immunohistochemical Study.

Introduction: Natural killer cells are believed to promote placental and trophoblastic growth and provide immune- modulation at maternal-fetal interface in pregnancy and their role in reproductive failure has been a matter of discussion.

Aim: To study CD56+ Natural killer cells in spontaneous pregnancy loss.

Materials And Methods: In this prospective observational study, formalin-fixed paraffin embedded sections from products of conception from twenty women each with spontaneous early pregnancy loss (test group) and elective pregnancy termination (control group). Immunohistochemical staining with CD 56 monoclonal antibody was done by avidin-biotin peroxidase technique. CD56+ cells in decidua were counted under light microscopy by two independent observers in ten high power fields (40X) and mean cell count taken. Student's paired 't'-test was used to statistically compare CD56+ NK cell population between the test and control groups.

Results: The mean number of CD56+ NK cells was higher in the decidual tissue of women who had spontaneous early pregnancy loss (mean±SD, 57.55±1.79) as compared to the mean number of CD56+ NK cells in the decidual tissue from women who underwent elective termination (mean±SD, 50.9±3.46). The difference was statistically significant (difference of 6.65 with 95% confidence interval of 4.76 to 8.54, p-value <0.0001).

Conclusion: This could imply that CD56+ NK cells have a role in the pathogenesis of spontaneous early pregnancy loss and further large scale studies can throw more light on the mechanism and designing of appropriate therapy.