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Keywords:

  • B lymphocytes;
  • NK cells;
  • flow cytometry

PROBLEM: TJ6 is a cytokine whose membrane form is regularly expressed on the B lymphocytes of women during pregnancy. In a previous study we have shown that pregnancies that end in a spontaneous abortion are characterized by an increase in natural killer (NK) cells and that NK cells in these pregnancies also expressed TJ6, whereas NK cells from pregnancies that terminate normally neither increase in number nor do they express significant amounts of the cytokine.

METHODS: To evaluate the ability of TJ6 to predict pregnancy outcome, 61 blood samples from pregnant women were studied. Blood samples were drawn between 5 and 12 weeks of gestation and analyzed for lymphocyte expression of TJ6 using Cytoron Absolute flow cytometry and two-color fluorescence. The percentage of CD19+ (B) cells and CD56+ (NK) cells that expressed TJ6 was calculated, and this percentage was correlated with subsequent pregnancy outcome classified as successful (viable birth) or unsuccessful (abortion, stillbirth). TJ6 CD19 and TJ6 CD56 was determined in 32 blood samples from women with successful pregnancy outcomes and 29 samples from women with unsuccessful pregnancy outcome.

RESULTS: The mean TJ6 CD19 expression for successful pregnancies was 10.6% and for unsuccessful pregnancies was 5.1% (P < 0.03). The mean TJ6 CD56+ percentage of circulating cells that express TJ6 expression for successful pregnancies was 3.3% and for unsuccessful pregnancies was 10.4% (P = 0.02). All unsuccessful pregnancies had less than 90% of circulating CD19 cells express TJ6 and/or greater than 50% of circulating CD56 cells express TJ6. Use of the expression of TJ6 on CD19 and CD56 cells during the first trimester predicts viable pregnancy with a sensitivity of 100%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 100%.

CONCLUSIONS: The work now being reported validates the hypothesis that expression of TJ6 on NK cells obtained from pregnant women predicts the outcome of pregnancy. In addition we show that this prognosticator can be reliably demonstrated early in the first trimester.