Decrease in the proportion of granulated CD56+ T-cells in patients with a history of recurrent abortion.

We investigated levels of CD56+ T-cells (CD3+ CD56+ cells) in peripheral circulation, which express one of the natural killer (NK) cell markers, by flow cytometry and with monoclonal antibodies in patients with a history of recurrent abortion. We compared these values with those obtained in normal women who were not pregnant as well as in normal pregnant subjects. The percentage of CD56+ T-cells in the peripheral blood of patients with a history of recurrent abortion was less than that in the non-pregnant or pregnant women. These results suggest that CD56+ T-cells with extrathymic properties may be associated with the maintenance of normal pregnancy in humans.