Microenvironment of the feto-maternal interface protects the semiallogenic fetus through its immunomodulatory activity on dendritic cells

Objective: To investigate the immunomodulatory activity of decidual culture supernatant on dendritic cell (DC) functions. Design: In vivo and in vitro experimental study using mice. Setting: Academic research laboratory. Animal(s): C57BL/6-mated female Balb/c mice. Intervention(s): Culture supematants of decidual cells obtained from the uteri of allogenic pregnant mice (Balb/c x C57BL/6) were collected. Dendritic cells were purified from Balb/c mice spleens and pulsed with antigen during overnight culture. In some cultures, decidual supernatant was added at 5%, 10%, or 20% final concentration. Endometrial culture supernatant-treated DCs served as a control. Antigen-pulsed DCs were injected into the front footpads of syngeneic mice. Main Outcome Measure(s): Lymph nodes of primed mice were removed 5 days after DC injection. Antigenspecific proliferation and interleukin-10 and interferon gamma production by lymphocytes were measured by 3 H-Thymidine incorporation and ELISA, respectively. Result(s): The results showed that decidual culture supernatant markedly blocked in vivo antigen presentation by DCs and inhibited their capacity to induce interferon gamma (but not interleukin-10) production by primed lymphocytes. Conclusion(s): It seems that soluble factors produced by decidual cells are important mediators of immunoregulation at the feto-matemal interface, which provide the two fundamental requirements for protection of the semiallogenic fetus, namely immunologic tolerance and predominance of T helper 2 immunity, through modulation of DCs function.