Korean J Obstet Gynecol.  2012 Jul;55(7):485-492. 10.5468/KJOG.2012.55.7.485.

Resistance of uterine radial artery blood flow is positively correlated with peripheral blood NK cell fraction in patients with unexplained recurrent spontaneous abortion

• Koo HS
• Yi HJ
• Lee MY
• Ahn HS
• Choi MH
• Sung NY
• Hwang YI
• Song IO
• Koong MK
• Kang IS
• Yang KM

• KMID: 1992558
• DOI: http://doi.org/10.5468/KJOG.2012.55.7.485

Abstract

OBJECTIVE
To evaluate whether increased peripheral blood inflammatory immune cell can induce decrease of uterine blood flow in patients with unexplained recurrent spontaneous abortion (RSA).
METHODS
This study designed prospectively 33 pregnant women between 5 to 7 gestational weeks with a history of unexplained RSA included in this study. 47 normal pregnant women between 5 to 7 gestational weeks without history of infertility and/or RSA included as a control. Peripheral blood natural killer (pbNK) (CD3-/56+) fractions among peripheral blood monocyte (PBMC) were checked by flow cytometry. Uterine color-pulsed Doppler trans-vaginal ultrasound for evaluation of uterine radial artery RI was checked. Uterine radial artery resistance index (RI) compared between study and control group. After then, uterine radial artery RI was compared between high pbNK cell fraction above 12.1% among PBMC and normal pbNK cells fraction below 12.1%. Correlation between pbNK cell fraction to uterine radial artery RI was also evaluated.
RESULTS
Uterine radial artery RI in early pregnancy was significantly higher in patients with RSA than that of normal control (0.60 +/- 0.14 vs. 0.54 +/- 0.12, P=0.039). Especially, the mean value of uterine radial artery RI in RSA patients with elevated pbNK cells was significantly increased than that of normal control (0.62 +/- 0.13 vs. 0.54 +/- 0.12, P=0.029). Otherwise, pbNK cell fractions among PBMC displayed strong positive correlation to uterine radial artery RI (Pearson's correlation coefficient P=0.001, r = 0.667).
CONCLUSION
Increased pbNK cells can evoke decreased uterine blood flow by their pro-inflammatory action on micro vascular structure such as uterine radial artery. This can be a one causative mechanism of inducing spontaneous abortion by increased NK cells. But, larger scaled study is needed for clarify our results.

Keyword

Recurrent spontaneous abortion; Natural killer cell; Uterine radial artery resistance index

MeSH Terms

Abortion, Spontaneous
Female
Flow Cytometry
Humans
Infertility
Killer Cells, Natural
Monocytes
Pregnancy
Pregnant Women
Prospective Studies
Radial Artery

Figure

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  Fig. 1 Diagram of study subjects. pbNK, peripheral blood natural killer.

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  Fig. 2 Analysis of peripheral blood natural killer (pbNK) cell fraction and NK cell cytolytic activities (NKA) by using flow cytometry at gestational age 5 to 7 weeks (A) analysis of pbNK by using flowcytometry. Circled area in left figure indicated lymphocyte population among peripheral blood monocyte (PBMC). Circled area in right figure indicated NK cell (CD3-56+) cell population among lymphocte. (B) Analysis of NKA by using flow cytometry. NKA was checked by % dead target cell (K562 cell) after 2 hour incubation of PBMC in three different effector to target (E:T) ratio.

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  Fig. 3 Measurement of uterine blood flow by Doppler ultrasonogram. Resistance index (RI)=(peak systolic velocity-end diastolic velocity)/peak systolic velocity; Z1, zone for the 1st time measured resistance index; Z2, zone for the 2nd time measured resistance index; Z3, zone for the 3rd time measured resistance index.

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  Fig. 4 Comparison of mean uterine radial artery resistance index. RI, resistance index; pbNK, peripheral blood natural killer.

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  Fig. 5 Correration of uterine radial artery resistnace index and pbNK cell fraction in RSA group. RI, resistance index; RSA, recurrent spontaneous abortion.

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  Fig. 6 Correlation between uterine RA-RI and pbNK cell fraction in normal and elevated NK groups. RA-RI, radial artery-resistance index; pbNK, peripheral blood natural killer.

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