Diagnostic significance of assessing peripheral natural killer cells in women with recurrent pregnancy loss

Aim: to assess peripheral blood NK cell (pNK) counts in women with recurrent pregnancy loss.
Materials and Methods. There were examined 102 women: 28 non-pregnant (immediately after repeatedly terminated pregnancy, group IA) and 34 pregnant women with history of previous recurrent pregnancy loss (group IB). Control and comparison groups were consisted of healthy women lacking any recorded miscarriage: 20 non-pregnant (group IIA) and 20 pregnant women (group IIB), respectively. Along with assessing complete blood count range, all subjects were analyzed percentage of pNK cell CD16bright(+) CD56dim(-) cytotoxic phenotype by using fluorescence microscopy as well as level of cytokines IL-2, IL-6, IL-10, tumor necrosis factor (TNF-α), vascular endothelial growth factor (VEGF) and interferon-gamma (IFN-γ) using ELISA.
Results. It was found that the level of NK cell cytotoxic phenotype - percentage of CD16+CD56- was elevated in both groups: groups: group IA - 36.5 % collared with the control group IIA - 27.5% (р < 0.05); in group IB up to 37.0 %, in comparison group IIB - 27.4% (р < 0.01). It was further corroborated by increased level of serum cytokine IL-6 IL-6 comprising in group IA vs. IIA - 28.5 pg/ml vs. 14.2 pg/ml (р < 0.01) as well as in group IB vs. IIB up to 16.7 pg/ml vs. 12.2 pg/ml (р < 0.01), respectively. However, level of serum IL-2 and IL-10 did not significantly differ in all groups examined. Interestingly, level of VEGF in subjects aged 21-30 years was elevated: in non-pregnant (group IA) vs. control (group IIA) - up to 548.5 pg/ml vs. 310.8 pg/ml (р < 0.01); pregnant women (IB) vs. comparison group (IIB) - insignificantly elevated up to 476.1 pg/ml vs. 381.5 pg/ml, respectively. In contrast, no significant changes were observed in 31-40-year group. Concentration of IFN-γ in group IA vs. control group (IIA) was increased up to 9.2 pg/ml vs.8.64 pg/ml; group IB vs. comparison group - up to 8.36 pg/ml vs. 7.56 pg/ml, respectively.
Conclusion. Elevated percentage of cytotoxic CD16+CD56- NK cells in peripheral blood results in imbalance of immune-related parameters that directly correlated with increased serum level of IL-2, IL-6, TNF-α that may alter maternal immune tolerance to the fetus and subsequently resulting in recurrent pregnancy loss. Hence, the aforementioned data may be used as diagnostic and prognostic criteria in recurrent pregnancy losses.

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