Fas ligand in the uterus of the non-pregnant mouse induces apoptosis of CD4+ T cells.

The role of FasL in the reproductive tissues of the non-pregnant mouse may be the induction of apoptosis of activated T cells for the prevention of unwanted inflammatory responses secondary to infection. This study was undertaken to identify cell and tissue types that typically express FasL in the uterus and oviduct of the mouse and to establish whether FasL on the surface of these cells was able to induce T cell apoptosis. FasL in the mouse uterus and oviduct was demonstrated using three independent methods: RT-PCR, Western blot and immunocytochemistry. The protein was present in the epithelial and mesenchymal cells of the uterus and showed a granular pattern in the apical epithelial portion. Although this suggests the presence of vesicles, surface expression was also detected by flow cytometry of isolated uterine cells. Exogenous administration of estradiol and progesterone had no significant effect on the expression and localization of FasL. The ability of uterine cells to induce FasL-dependent apoptosis of activated CD4+T cells was examined by incubation of phytohemagglutinin-treated T cells with cultured uterine cells. TUNEL and flow cytometric analyses showed that CD4+T cells experienced apoptosis after 5h of co-incubation. Neutralizing antibodies inhibited apoptosis demonstrating that a biologically active FasL is present in the reproductive tissues of the mouse. Results indicate that FasL is a biologically active molecule present in epithelial and mesenchymal cells of the uterus and the oviduct of the non-pregnant mouse that might restrain local immune response by induction of apoptosis of CD4+T lymphocytes.

Fas ligand(+) fallopian tube epithelium induces apoptosis in both Fas receptor(+) T lymphocytes and endometrial cells.

OBJECTIVE: To establish whether human fallopian tube (FT) epithelium can induce apoptosis in T lymphocytes and endometrial cells. DESIGN: Laboratory-based study. SETTING: Hospital. PATIENT(S): Women undergoing abdominal hysterectomy for FT samples, and women volunteers with and without endometriosis for endometrial biopsies. INTERVENTION(S): FT samples obtained at time of surgery performed in reproductive-aged women with normal menstrual cycles. MAIN OUTCOME MEASURE(S): T lymphocytes or endometrial cells coincubated with FT epithelial cells and assayed for apoptosis by DNA nick-end labeling and caspase-3 activity, with the presence of Fas ligand (FasL) and Fas receptor (FasR) assessed by indirect immunostaining. RESULT(S): The epithelium of the FT-induced apoptosis in T cells as well as in human endometrial cells. The mechanism probably involves the FasL/FasR system; accordingly, we observed FasL at the apical surface of the epithelium and in the stroma of the FT at all phases of the menstrual cycle except during the early proliferative phase. The endometrial samples from patients with endometriosis did not express FasR and were resistant to apoptosis. CONCLUSION(S): In both FasR(+) T lymphocytes and endometrial cells, FasL(+) FT cells induce apoptosis. Data suggest that the FT epithelium acts as a barrier to limit the influx of lymphocytes as well as endometrial cells ascending the tube. Failure of these regulatory mechanisms may be related to the development of endometriosis.