Differential expression of KIR/NKAT2 and CD94 molecules on decidual and peripheral blood CD56bright and CD56dim natural killer cell subsets

Abstract

To investigate killer inhibitory receptor (KIR) expression by natural killer (NK) cells in early pregnancy. Case-control study of immunologic markers. University hospital. Thirty pregnant women and 22 nonpregnant women. Peripheral venous blood sampling and decidual tissue collection after elective abortion. Flow cytometry was used to assess expression of KIR by NK cells in the cell samples. In contrast to CD56(bright) peripheral blood NK cells, CD56(dim) cells express killer cell Ig-like receptor KIR/NKAT2. However, KIR/NKAT2 and lectin-like CD94 are present on both subsets of decidual NK cells. We found no differences between peripheral blood NK cell subsets from pregnant and nonpregnant women. Our findings demonstrate that NK cell subsets, distributed in accordance with CD56 molecule density on cell surface, express killer inhibitory receptors CD94 and KIR/NKAT2 in a different way. Our data support the view that CD56(bright)KIR/NKAT2+CD94+ decidual NK cells are specialized NK cells that have an important role to play in early pregnancy.