Differential expression of KIR/NKAT2 and CD94 molecules on decidual and peripheral blood CD56 bright and CD56 dim natural killer cell subsets

Abstract

Objective To investigate killer inhibitory receptor (KIR) expression by natural killer (NK) cells in early pregnancy. Design Case-control study of immunologic markers. Setting University hospital. Patient(s) Thirty pregnant women and 22 nonpregnant women. Intervention(s) Peripheral venous blood sampling and decidual tissue collection after elective abortion. Main outcome measure(s) Flow cytometry was used to assess expression of KIR by NK cells in the cell samples. Result(s) 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. Conclusion(s) 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 brightKIR/NKAT2 +CD94 + decidual NK cells are specialized NK cells that have an important role to play in early pregnancy.