Changes of human decidual natural killer cells cocultured with YFP-Toxoplasma gondii: implications for abnormal pregnancy.

OBJECTIVE

To investigate the changes of human decidual natural killer (dNK) cells cocultured with Toxoplasma gondii in vitro and to infer implications on pregnancy.

DESIGN

Case-control study.

SETTING

College and hospital.

PATIENT(S): Decidual tissue was obtained from 85 patients undergoing voluntary abortion during the first trimester of gestation (6-12 weeks).

INTERVENTION(S): None.

MAIN OUTCOME MEASURE(S): The dNK cells were isolated and infected with YFP-Toxoplasma gondii. Cells were observed by fluorescence and confocal microscopy. The CD56(bright)CD16(-)/CD56(dim)CD16(+) dNK ratio, expression of KIR2DL4, ILT-2, and NKG2D on dNK cells were analyzed by flow cytometry and the cytotoxic activity of infected dNK cells were evaluated.

RESULT(S): The CD56(dim)CD16(+)/CD56(bright)CD16(-) dNK ratio was significantly elevated at 12, 24, and 48 hours after YFP-T. gondii infection. Expression of KIR2DL4, ILT-2, and NKG2D were increased after infection, but NKG2D were significantly higher than those of KIR2DL4 and ILT-2. Both the CD56(dim)CD16(+)/CD56(bright)CD16(-) dNK ratio and NKG2D expression were correlated with dNK cytotoxic activity.

CONCLUSION(S): Enhanced dNK cytotoxicity due to increased CD16 and NKG2D expression may contribute to abnormal pregnancy outcomes observed with maternal infection with T. gondii.