Problem: The presence of immunosuppressive cells within the endometrium and decidua is crucial for establishing maternal immune tolerance against fetal antigens. We decided to evaluate the subpopulations of Treg cells and B7H4 macrophages in eutopic endometrium typified by Arias Stella reaction during the development of Fallopian tube pregnancy as well as in decidua at the time of spontaneous abortion (SA), and to compare these findings to those observed in the endometrium during the secretory cycle phase of healthy women.
Method of study: The decidual tissue samples evaluated in our study were obtained from 26 women who underwent curettage as a result of the following circumstances: five of the women because of a laparoscopic procedure necessitated by Fallopian tube pregnancy, and 11 of them because of SA. The control group consisted of 10 patients on whom curettage was preformed as an additional procedure during laparoscopic myomectomy. The presence of regulatory T-cells and B7H4-positive macrophages in the samples was analysed by fluorescence-activated cell sorter (FAC-Scan).
Results: Both the percentages of FOXP3(+) cells in the subpopulation of CD25(+) CD4(+) T lymphocytes and the percentage of B7H4-positive cells in the macrophage subpopulation found in the deciduae of patients suffering SA were higher than those found in eutopic endometrium with Arias Stella reaction. No such differences in the percentages of these cells were observed when the tissue samples from patients with SA were compared with those from the control group. The percentage of B7H4-positive macrophages, however, was found to be significantly lower in endometrium with Arias Stella reaction in comparison to that observed in secretory endometrium.
Conclusion: The alterations in both the Treg cell and suppressive B7H4(+) macrophage subpopulations would seem to be related to the suppression of maternal immune cells in the endometrium at the beginning of decidualization.