IMMUNOLOGY DEPARTMENT, SCHOOL OF MEDICAL SCIENCES, TARBIAT MODARRES UNIVERSITY, TEHRAN, IRAN
Introduction: Decidua as the nearest mother's tissue layer to the fetus which is in direct contact with the embryo has an important role in composing the appropriate microenvironment for protection of allogenic fetus from mother's immune response. In this study the effect of supernatant from culture of decidual cells on dendritic cells regarding the induction of T-cell allogenic proliferation response and Indoleamine 2, 3 dioxygenase (IDO) enzyme presentation was evaluated.
Material and Methods: Decidua of allogenic pregnant mice (C57BL/2 x Balb/c) were isolated at mid gestation and after their enzymatic digestion, the obtained cell suspensions were cultured. The cell supernatants were collected after 48 hours of culture and frizzed (-70 ºc) until use. Dendritic cells were obtained from the spleen of C57BL/6 mice by enzymatic digestion and Nycodenz gradient centrifugation. The adherent cells obtained after 2 hours of culturing were incubated with various concentrations of decidual supernatant for 12-15 hours, during this time dendritic cells maturated and floated. T lymphocytes were isolated from brachial and axillary lymph nodes of Balb/c mice by nylon wool method. Decidual supernatant of treated dendritic cells were cultured with allogenic T cells after γ-irradiation (3000 rad) in MLR condition and cell proliferation was measured by 3H-thymidine incorporation. For identification of suppressive mechanism of IDO enzyme its specific inhibitor (L-Methyl-Tryptophan) was used.
Results: Flowcytometric analysis showed that dendritic cells and Tcells were %93±2 and %91±2 pure, respectively. MLR results showed a decrease in T cell proliferation response when dendritic cells were treated with decidual supernatant of pregnant mice. While treatment of dendritic cells with culture supernatant of none pregnant mice uterus didn't show such effect. This suppression was adjusted by addition of L-Methyl tryptophan.
Conclusion: Decidual supernatant may suppress the T-cell responses via IDO induction in dendritic cells. Keywords: Supernatant of decidual cell culture, Dendritic cells, Indole amine 2, 3 dioxygenase, Allogenic MLR