Natural killer cell receptor expression by human first trimester decidual granular leukocytes and T-lymphocytes.

Problem: Detailed analysis of the expression of natural killer (NK) cell activatory and inhibitory receptors by human decidual leukocyte subpopulations has not been undertaken.

Method Of Study: Expression of the natural cytotoxicity receptors NKp30, NKp44 and NKp46 by decidual leukocytes were studied by reverse transcriptase polymerase chain reaction. Expression of the killer cell Ig-like receptors CD158a and CD158b on decidual T cells were studied by flow cytometry.

Results: First trimester decidual leukocytes expressed mRNA for the NKp30 and NKp46 receptors but expression of NKp44, a marker of activated NK cells, was not detected. A mean of 11.8 and 15.8% of decidual T cells expressed CD158a or 158b, respectively, while only around 1% of peripheral blood T cells were CD158a+ or CD158b+.

Conclusions: Like peripheral blood NK cells, decidual NK cells express the natural cytotoxicity receptors NKp30 and NKp46 but the significance of this will not become apparent until ligands for these molecules have been identified. Only a minority of decidual T cells express CD158, indicating that this is not a mechanism for inhibition of cytotoxicity mediated by all decidual T cells.