Increased T‐Cell Activation in Decidua Parietalis Compared to Decidua Basalis in Uncomplicated Human Term Pregnancy

PROBLEM: The aim of this study was to quantify and compare activated T cells in term decidua basalis and parietalis using flow cytometry. METHOD OF STUDY: Term decidua basalis and parietalis samples were obtained from 20 placentas collected after elective caesarean section. Percentages of leukocyte subclasses within the CD45+ cell fraction and activated T cells were determined by flow cytometry. RESULTS: There was no significant difference in CD45+, CD14+, CD19+, and CD3+ cell percentages. However, within the CD3+ population, there were significantly more T-cell receptor-gamma(delta)+ (TCR-gamma(delta)-) and CD8+ cells in decidua parietalis compared with decidua basalis. More importantly, percentages of T cells expressing CD25, human leukocyte antigen (HLA)-DR, CD45RO, and CD69 markers were significantly increased in decidua parietalis. CONCLUSION: These findings suggest that there are more activated T cells in decidua parietalis than in decidua basalis. Further investigation into differences between the two decidual sites may expand our understanding of the immunology of the maternal-fetal interface.