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Problem: CD8 T-cells are present at a lower frequency in human decidua than in peripheral blood. Because transforming growth factor (TGF)-beta 2 down-regulates CD4 membrane expression, its contribution, as well as the contribution of TGF-beta 1 and prostaglandin (PG) E2, to the modulation CD8 expression was studied using human peripheral blood lymphocytes (PBLs)., Method of Study: PBLs were cultured with TGF-beta 1, TGF-beta 2, PGE 2, PGI 2, or day-12 rabbit blastocoelic fluid (BF) that was or was not depleted of TGF-beta 2 and/or PGE 2. Quantum Simply Cellular Microbeads were then used to evaluate CD8 membrane expression levels., Results: This study is the first demonstration that treatment of PBLs with TGF-beta 1, TGF-beta 2, and PGE 2 leads to a dose-dependent decrease in CD8 expression. A significant inhibition was observed at 2.5 mg/mL for TGF-beta 2, 5 ng/mL for TGF-beta 1, and 10 ng/mL for PGE 2. In contrast, PGI 2 had no effect. Treatment of PBLs with BF day-12 decreased CD8 expression. This effect, however, was not observed when BF was depleted of TGF-beta 2 and/or PGE 2., Conclusions: Our results suggest that TGF-beta s and PGE 2 are important modulators of CD8 membrane expression in human lymphocytes. Because TGF-beta 1, TGF-beta 2, and PGE 2 are produced by the conceptus and by uterine cells and because the effect is observed after only 3 days of treatment, the present data suggest that these substances can locally modulate the phenotype of lymphocytes at the fetomaternal interface. Such modulation may explain, at least partly, the changes observed in the population of decidual lymphocytes during pregnancy.

Problem: During normal pregnancy, major changes occur in the production of Th2/Th1 cytokines at the feto-maternal interface. Th2 cytokines such as interleukin-4 (IL-4) or interleukin-10 (IL-10) are predominantly produced locally in the uterine and placental tissues, whereas the production of Th1 cytokines such as tumor necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma) are decreased. Because these modulation might be induced by the embryo, the current study was carried out to test the effect of rabbit blastocoelic fluid on the production of Th2/Th1 cytokines by lymphocytes, and to investigate the possible implication of transforming growth factor beta 2 (TGF-beta 2) prostaglandin E2 (PGE2) as modulators of the production of these cytokines., Method of Study: Human peripheral blood lymphocytes (PBL) were cultured along with ConcanavalinA(Con A), and rabbit blastocoelic fluid was collected on day 12 of gestation (BF d-12). Concentrations of cytokines in culture media were determined by enzyme-linked immunoadsorbent assay (ELISA)., Results: Addition of BF d-12 in the culture medium induced a strong inhibition of IL-2, TNF-alpha, IL-10, and granulocyte-macrophage colony-stimulating factor (GM-CSF) production. However, an initial pretreatment of the lymphocytes with BF d-12, followed by a Con A stimulation, led to a marked increase in GM-CSF production, whereas IL-2, TNF-alpha, and IL-10 secretions were inhibited. It was also demonstrated, for the first time, that a pretreatment of the lymphocytes with TGF-beta 2 and PGE2 increased GM-CSF production to the same level reached after the addition of BF d-12. Furthermore, removal of TGF-beta 2 and PGE2 from BF d-12 by affinity chromatography reduced the effect of BF d-12 on GM-CSF production., Conclusions: Taken together, these findings suggest that the embryo, in modulating harmful and beneficial cytokine production locally, plays an active role in its protection against maternal immune cellular assault. These results also emphasize the importance of growth factors for successfully maintaining pregnancy.

Problem: During pregnancy, major changes occur in the decidual cell population. One of these changes involves some phenotypical transformations of lymphocyte sub-populations. Since these variations might be due to the presence of the embryo, the current study was designed to investigate the implication of blastocoelic fluid (BF) in these changes and to determine the mechanism by which this phenomenon occurs., Method: Lymphocytes isolated from human peripheral blood (PBL) were cultured for 72 h in RPMI-FCS 10% and with or without BF day 12 (BF d-12) or Concanavalin A (ConA). After 72 h, T cells were labelled with anti-CD4 antibodies and Quantum Simply Cellular microbeads were used as a standard to evaluate the antibody binding capacity (ABC)., Results: Treatment of human PBL with BF d-12 decreases the percentage of CD4 and TCR positive cells, as compared to non-stimulated cells, but has no significant effect on CD2, CD3, and CD8 positive cells. It was also demonstrated, for the first time, that transforming growth factor beta-2 (TGF beta 2) in BF day 12 diminishes the percentage of CD4 positive cells by downregulating CD4 membrane expression on leucocytes., Conclusion: These findings suggest that the embryo plays a role in its own protection. Furthermore, it is predicted that any tissue producing TGF beta 2, such as certain types of tumor, downregulates the immune response, thus allowing tumor growth.