The Experts below are selected from a list of 174 Experts worldwide ranked by ideXlab platform
M D Mitchell - One of the best experts on this subject based on the ideXlab platform.
-
subCellular localization of prostaglandin h synthase 2 in a human Amnion Cell line implications for nuclear localized prostaglandin signaling pathways
Prostaglandins Leukotrienes and Essential Fatty Acids, 2000Co-Authors: K W Marvin, R L Eykholt, M D MitchellAbstract:We have determined that prostaglandin H synthase-2 localises strongly to the nuclear membrane as well as being found in the endoplasmic reticulum in human Amnion-derived WISH Cells which have been stimulated with interleukin 1 beta and phorbol ester. This is consistent with findings in Cells of non-reproductive origin. There is strong evidence that prostaglandin J(2) derivatives, which in other tissues exhibit tumour suppressing, antiproliferative and/or differentiation promoting activities, act through binding of intraCellular receptors which then enter the nucleus. In addition, some arachidonic acid derivatives are clearly generated by enzymes at the nuclear envelope and localise to sites in nuclei or bind sites in nuclei. The WISH Cell line will make an exCellent system for studying these perinuclear intraCellular prostanoid signaling mechanisms. (C) 2000 Harcourt Publishers Ltd.
-
Action of immunoregulatory agents on 5-HETE production by cultured human Amnion Cells.
Journal of reproductive immunology, 1997Co-Authors: S S Edwin, M D Mitchell, D J DudleyAbstract:Labor in women is associated with increased amniotic fluid prostaglandin (PG) concentrations. AF of women with term and preterm labor also contains elevated concentrations of arachidonic acid metabolites from the lipoxygenase pathway including 5-hydroxyeicosatetraenoic acid (5-HETE). We and others have shown that 5-HETE production within the uterus is increased by inflammatory cytokines. The purpose of this study was to determine whether 5-HETE production is regulated by immunotherapeutic agents that inhibit prostaglandin E2 (PGE2) production, such as interleukin-10 (IL-10) and cyclosporin A (CsA). Cultured confluent Amnion Cells were incubated for 16 hr with IL-10 (1 100 ng/ml), CsA (1 1000 ng/ml), or controls. Additional incubation of IL-10 and CsA (both at 10 and 100 ng/ml) were conducted on Amnion Cells in the presence and absence of interleukin-1 beta at 1 ng/ml. 5-HETE was measured by radioimmunoassay and Cellular protein determined. IL-1 beta stimulated Amnion Cell 5-HETE production as expected. However, 5-HETE production by Amnion Cells was significantly inhibited by incubation with IL-10 and CsA, and both significantly attenuated 5-HETE production in response to IL-1 beta. We speculate that the inhibitory effect of IL-10 and CsA on Amnion Cell 5-HETE production is at the level of substrate release or inhibition of 5-lipoxygenase and that the use of these agents during pregnancy may not adversely affect pregnancy outcomes.
-
Actions of immunoregulatory agents on 5-HETE production by cultured human Amnion Cells
Journal of Reproductive Immunology, 1997Co-Authors: S S Edwin, M D Mitchell, D J DudleyAbstract:Abstract Labor in women is associated with increased amniotic fluid prostaglandin (PG) concentrations. AF of women with term and preterm labor also contains elevated concentrations of arachidonic acid metabolites from the lipoxygenase pathway including 5-hydroxyeicosatetranoic acid (5-HETE). We and others have shown that 5-HETE production within the uterus is increased by inflammatory cytokines. The purpose of this study was to determine whether 5-HETE production is regulated by immunotherapeutic agents that inhibit prostaglandin E 2 (PGE 2 ) production, such as interleukin-10 (IL-10) and cyclosporin A (CsA). Cultured confluent Amnion Cells were incubated for 16 h with IL-10 (1–100 ng/ml), CsA (1–1000 ng/ml), or controls. Additional incubations of IL-10, and CsA (both at 10 and 100 ng/ml) were conducted on Amnion Cells in the presence and absence of interleukin-1 β at 1 ng/ml. 5-HETE was measured by radioimmunoassay and Cellular protein determined. IL-1 β stimulated Amnion Cell 5-HETE production as expected. However, 5-HETE production by Amnion Cells was significantly inhibited by incubation with IL-10 and CsA, and both significantly attenuated 5-HETE production in response to IL-1 β . We speculate that the inhibitory effect of IL-10 and CsA on Amnion Cell 5-HETE production is at the level of substrate release or inhibition of 5-lipoxygenase and that the use of these agents during pregnancy may not adversely affect pregnancy outcomes.
-
CYCLOSPORIN A INHIBITS PROSTAGLANDIN E2 PRODUCTION BY FETAL Amnion CellS IN RESPONSE TO VARIOUS STIMULI
Prostaglandins, 1996Co-Authors: S S Edwin, D J Dudley, D. Ware Branch, James R. Scott, Robert M. Silver, M D MitchellAbstract:Use of cyclosporin A as part of an immunosuppressive regimen in pregnant transplant patients is not uncommon. Although successful pregnancies have been reported with the use of various immunosuppressive agents including cyclosporin A, the concern for fetal outcome still remains. Our purpose was to evaluate the effects of immunosuppressive cyclosporin A on prostaglandin E2 (PGE2) production by human fetal Amnion. Amnion Cells were isolated from term placentae obtained at elective cesarean section before the onset of labor. Cells were grown to confluence and then incubated for 16 hours with cyclosporin A (1-1000 ng/ml) in the presence and absence of interleukin 1 beta (IL-1 beta, 1 ng/ml), phorbol 12-myristate 13-acetate (PMA, 10(-7) M) and ionomycin (0.5 microM). PGE2 was measured by radioimmunoassay and Cellular protein determined. IL-1 beta, PMA and ionomycin all stimulated Amnion Cell PGE2 production as expected. However, these stimulatory actions were attenuated by at least 50% when Cells were co-incubated with cyclosporin A (1000 ng/ml). Concentrations of cyclosporin A tested included the therapeutic range (250-1000 ng/ml). Our results indicate that cyclosporin A does not stimulate Amnion Cell PGE2 production and is probably unrelated to preterm labor and delivery in allograft recipients.
-
Actions of interleukin-4 on prostaglandin biosynthesis by human Amnion Cells
Prostaglandins leukotrienes and essential fatty acids, 1994Co-Authors: Sharlene Adamson, S S Edwin, S. Lamarche, M D MitchellAbstract:The effects of interleukin-4 (IL-4) on Amnion prostaglandin (PG) production have been determined. Human Amnion Cells from term placentae were grown to confluence and incubated with IL-4 either alone or with various concentrations of epidermal growth factor (EGF) of ionomycin. PGE2 production was determined using a specific radioimmunoassay. IL-4 alone stimulated PGE2 production in Amnion Cells in a concentration-related manner. IL-4 significantly enhanced the stimulatory actions of ionomycin and EGF on Amnion Cell PGE2 production. Ionomycin and IL-4 acted synergistically in their effects on PGE2 production by Amnion Cells whereas EGF and IL-4 acted more additively in this respect. We suggest that IL-4 production by immune effector Cells in gestational tissues may contribute to the mechanisms of labor at term and preterm.
David M. Olson - One of the best experts on this subject based on the ideXlab platform.
-
Tyrosine kinase inhibitors block the glucocorticoid stimulation of prostaglandin endoperoxide H synthase expression in Amnion Cells.
Canadian journal of physiology and pharmacology, 1999Co-Authors: Tamas Zakar, Jane E. Mijovic, Damyanti Bhardwaj, David M. OlsonAbstract:Human Amnion Cells in primary culture respond to glucocorticoids in a characteristic fashion by the increased expression of the inducible prostaglandin endoperoxide H synthase isoenzyme, PGHS-2. Since PGHS-2 induction by agonists generally involves tyrosine kinases, we examined the possibility that the glucocorticoid stimulation of PGHS-2 in the Amnion Cells is tyrosine kinase dependent. PGHS-2 expression was stimulated in confluent, serum-starved Amnion Cells with dexamethasone, and the effect of the tyrosine kinase inhibitors herbimycin A and tyrphostins AG126, AG1288, and A1 on enzyme activity induction was determined. All four inhibitors blocked the increase of PGHS activity in a concentration-dependent manner with IC50 values of 0.077 +/- 0.05, 15.38 +/- 5.14, 20.91 +/- 3.1, and 29.77 +/- 8.21 microM, respectively (mean +/- SE, n = 4). Dexamethasone increased (approximately twofold) the tyrosine phosphorylation of 120-, 110-, and 77-kDa proteins in Cell extracts, and herbimycin A selectively blocked the phosphorylation of the 110-kDa phosphoprotein. The stimulation of the steady-state level of PGHS-2 mRNA by dexamethasone was also inhibited by herbimycin A. These results suggest that glucocorticoids induce PGHS-2 expression in Amnion Cells with the involvement of tyrosine kinase(s). The role of tyrosine kinase dependent mechanisms in the control of Amnion Cell responsiveness to corticosteroids remains to be established.
-
stimulation of cultured Amnion Cell prostaglandin endoperoxide h synthase activity by glucocorticoids and phorbol ester
American Journal of Obstetrics and Gynecology, 1993Co-Authors: Zofia Smieja, Tamas Zakar, David M. OlsonAbstract:Objective : The effects of a phorbol ester activator of protein kinase C and the glucocorticoids Cortisol and dexamethasone on the enzyme activity of prostaglandin H synthase (cyclooxygenase) in confluent cultures of human Amnion epithelial Cells were tested. Study design : Amnion epithelial Cells from spontaneously delivered placentas at term were isolated and grown in culture until confluent. The activity of the enzyme prostaglandin H synthase was determined in these Cells with a well-characterized enzyme assay monitoring the conversion of arachidonic acid to prostaglandin E 2 . The Michaelis-Menten constant and maximum velocity were determined from the substrate velocity data by means of Lineweaver-Burk plots. Results : Amnion Cells lost most of their prostaglandin H synthase activity within 2 days of culturing. This activity could be restored when Cells were treated with 12-O-tetradecanoyl phorbol-13-acetate, a phorbol ester activator of protein kinase C, or with the glucocorticoids Cortisol and dexamethasone. Epidermal growth factor also increased the specific activity, whereas 17s-estradiol had no effect on the specific activity of the enzyme. There was a direct correlation between the specific activity of prostaglandin H synthase and the output of prostaglandin E 2 by Cells treated with these agonists. Conclusion : Our data support the view that increases in prostaglandin H synthase specific activity in intrauterine tissues can be caused by stimulation by specific agonists, and this in turn is responsible for enhanced prostaglandin output by these tissues.
-
Glucocorticoid stimulation of Amnion Cell prostaglandin synthesis: suppression by protein kinase C inhibitors and independence of phorbol ester-sensitive protein kinase C.
Biochimica et biophysica acta, 1992Co-Authors: Tamas Zakar, Elizabeth Anne Macleod, David M. OlsonAbstract:Glucocorticoids stimulate the prostaglandin E2 production of confluent Amnion Cell cultures, but have no stimulatory effect on the PGE2 output of freshly isolated human Amnion Cells. Since protein phosphorylation may modify the responsiveness of target Cells to steroids, and activators of protein kinase C (PKC), as well as corticosteroids, promote Amnion Cell PGE2 output by stimulating the synthesis of prostaglandin endoperoxide H synthase (PGHS), we investigated the possibility that PKC is involved in the glucocorticoid-induction of PGE2 synthesis in cultured Amnion Cells. The dexamethasone-induced PGE2 output of arachidonate-stimulated Cells was blocked by the protein kinase inhibitors staurosporine, K-252a, H7, HA1004, and sphinganine, in a manner consistent with their effect on PKC. However, dexamethasone increased the PGE2 production of cultures treated with maximally effective concentrations of the PKC-activator compound TPA. Moreover, dexamethasone stimulated PGE2 synthesis in cultures which were desensitized to TPA-stimulation by prolonged phorbol ester treatment. Concentration-dependence studies showed that staurosporine completely (greater than 95%) blocked glucocorticoid-provoked PGE2 synthesis at concentrations which did not inhibit TPA-stimulated prostaglandin output, and that K-252a inhibited the effect of TPA by more than 95% at concentrations which decreased the effect of dexamethasone only moderately (approximately 40%). Dibutyryl cyclic AMP had no influence on the basal- or dexamethasone-stimulated PGE2 production, and on the staurosporine inhibition of the steroid effect. These results show that glucocorticoids and phorbol esters control Amnion PGE2 production by separate regulatory mechanisms. It is suggested that the response of human Amnion Cells to glucocorticoids is modulated by protein kinase(s) other than phorbol ester-sensitive PKC and cyclic AMP-dependent protein kinase.
Ramkumar Menon - One of the best experts on this subject based on the ideXlab platform.
-
damage associated molecular pattern markers hmgb1 and Cell free fetal telomere fragments in oxidative stressed Amnion epithelial Cell derived exosomes
Journal of Reproductive Immunology, 2017Co-Authors: Samantha Shellermiller, George R Saade, Rheanna Urrabazgarza, Ramkumar MenonAbstract:Abstract Term labor in humans is associated with increased oxidative stress (OS) −induced senescence and damages to Amnion epithelial Cells (AECs). Senescent fetal Cells release alarmin high-mobility group box 1 (HMGB1) and Cell-free fetal telomere fragments (cffTF) which can be carried by exosomes to other uterine tissues to produce parturition-associated inflammatory changes. This study characterized AEC-derived exosomes under normal and OS conditions and their packaging of HMGB1 and cffTF. Primary AECs were treated with either standard media or oxidative stress-induced media (exposure to cigarette smoke extract for 48 h). Senescence was determined, and exosomes were isolated and characterized. To colocalize HMGB1 and cffTF in Amnion exosomes, immunofluorescent staining and in situ hybridization were performed, followed by confocal microscopy. Next generation sequencing (NGS) determined exosomal cffTF and other Cell-free Amnion Cell DNA specificity. Regardless of condition, primary AECs produce exosomes with a classic size, shape, and markers. OS and senescence caused the translocation of HMGB1 and cffTF from AECs’ nuclei to cytoplasm compared to untreated Cells, which was inhibited by antioxidant N-acetyl cysteine (NAC). Linescans confirmed colocalization of HMGB1 and cffTF in exosomes were higher in the cytoplasm after CSE treatment compared to untreated AECs. NGS determined that besides cffTF, AEC exosomes also carry genomic and mitochondrial DNA, regardless of growth conditions. Sterile inflammatory markers HMGB1 and cffTF from senescent fetal Cells are packaged inside exosomes. We postulate that this exosomal cargo can act as a fetal signal at term and can cause labor-associated changes in neighboring tissues.
-
environmental pollutant polybrominated diphenyl ether a flame retardant induces primary Amnion Cell senescence
American Journal of Reproductive Immunology, 2015Co-Authors: Faranak Behnia, George R Saade, Morgan R Peltier, Ramkumar MenonAbstract:OBJECTIVE: Polybrominated diphenyl ethers (PBDEs) are documented to increase the risk for spontaneous preterm birth (PTB). We hypothesize that PBDEs cause oxidative stress (OS) that leads to fetal Cell senescence and inflammation associated with PTB. METHODS: Primary Amnion epithelial Cells (n = 5) isolated from term, not in labor pregnancies, were exposed to PBDE congeners 47 and 99 (each 5 μm). ROS kinetics was monitored. Morphologic changes, phospho-p38 MAPK (P-p38) activation, development of senescence, and induction of uterotonins (COX-2 expression) were quantified using light microscopy, Western blot, senescence-associated β-galactosidase (SA β-gal) staining, and qRT-PCR, respectively, after 48 and 72 hr of exposure. RESULTS: Both PBDE congeners induced ROS within 2 min compared to controls (P CONCLUSIONS: Congener-dependent OS response, p38 MAPK activation, senescence, and COX-2 expression were seen in human Amnion Cells by PBDEs. These findings demonstrate environment pollutant-induced senescence activation and inflammation can lead to pathways resulting in PTB. Language: en
-
telomere fragment induced Amnion Cell senescence a contributor to parturition
PLOS ONE, 2015Co-Authors: Jossimara Polettini, Faranak Behnia, Brandie D Taylor, George R Saade, Robert N Taylor, Ramkumar MenonAbstract:Oxidative stress (OS)-induced senescence of the amniochorion has been associated with parturition at term. We investigated whether telomere fragments shed into the amniotic fluid (AF) correlated with labor status and tested if exogenous telomere fragments (T-oligos) could induce human and murine Amnion Cell senescence. In a cross-sectional clinical study, AF telomere fragment concentrations quantitated by a validated real-time PCR assay were higher in women in labor at term compared to those not in labor. In vitro treatment of primary human Amnion epithelial Cells with 40 μM T-oligos ([TTAGGG]2) that mimic telomere fragments, activated p38MAPK, produced senescence-associated (SA) β-gal staining and increased interleukin (IL)-6 and IL-8 production compared to Cells treated with complementary DNA sequences (Cont-oligos, [AATCCC]2). T-oligos injected into the uteri of pregnant CD1 mice on day 14 of gestation, led to increased p38MAPK, SA-β-gal (SA β-gal) staining in murine amniotic sacs and higher AF IL-8 levels on day 18, compared to saline treated controls. In summary, term labor AF samples had higher telomere fragments than term not in labor AF. In vitro and in situ telomere fragments increased human and murine Amnion p38MAPK, senescence and inflammatory cytokines. We propose that telomere fragments released from senescent fetal Cells are indicative of fetal Cell aging. Based on our data, these telomere fragments cause oxidative stress associated damages to the term amniotic sac and force them to release other DAMPS, which, in turn, provide a sterile immune response that may be one of the many inflammatory signals required to initiate parturition at term.
K. Bry - One of the best experts on this subject based on the ideXlab platform.
-
Epidermal growth factor and transforming growth factor-α enhance the interleukin-1- and tumor necrosis factor-stimulated prostaglandin E2 production and the interleukin-1 specific binding on Amnion Cells
Prostaglandins leukotrienes and essential fatty acids, 1993Co-Authors: K. BryAbstract:Abstract Interleukin-1 (IL-1), tumor necrosis factor (TNF), epidermal growth factor (EGF), and transforming growth factor-α (TGF-α) stimulate prostaglandin E 2 (PGE 2 ) production by Amnion Cells whereas TGF-β inhibits the PGE 2 production. During labor occurring in the setting of infection, several of these cytokines may be simultaneously present in amniotic fluid. The aim of the present study was to examine whether these cytokines modify each others' effects on Amnion Cell PGE 2 production. Amnion Cells in monolayer culture were treated with IL-1, TNF, EGF, TGF-α, TGF-β1, their combination, or vehicle. The PGE 2 production and the specific binding of radiolabeled IL-1β on the Cells were measured. IL-1 or TNF in combination with EGF or TGF-α stimulated synergistically the production of PGE 2 by Amnion Cells. TGF-β1 did not modify the PGE 2 -stimulatory effect of EGFTGF-α. Untreated Amnion Cells expressed 1030 ± 100 IL-1β receptors per Cell with a binding affinity of 1.40 ± 0.26 nM. Treatment with TGF-α increased the number of receptors to 3940 ± 260 per Cell with no change in binding affinity. The potentiation of the PGE 2 -stimulatory effect of IL-1 by TGF-α may be related to its ability to induce IL-1 receptors on Amnion Cells. The synergistic effects of cytokines on Amnion Cell PGE 2 production may promote labor.
-
Synergistic stimulation of Amnion Cell prostaglandin E2 synthesis by interleukin-1, tumor necrosis factor and products from activated human granulocytes.
Prostaglandins leukotrienes and essential fatty acids, 1991Co-Authors: K. Bry, M. HallmanAbstract:Abstract We examined the interactions between supernatant from FMLP-activated human granulocytes, recombinant interleukin-1 (IL-1) and recombinant tumor necrosis factor (TNF) in the stimulation of prostaglandin E 2 (PGE 2 ) production by human Amnion Cells. Amnion Cells from elective term cesarian sections were cultured in monolayer culture. Human granulocytes were activated with FMLP and centrifuged to obtain Cell-free supernatant. Amnion Cells were treated with granulocyte supernatant, IL-1α, IL-1β, TNF-α, TNF-β, or different combinations of these. Each of the stimulators alone enhanced the PGE 2 production 5-to 27-fold. Granulocyte supernatant was synergistic with each of the cytokines. The combinations of IL-1α or IL-1β with either TNF-α or TNF-β caused a synergistic stimulation of Amnion Cell PGE 2 production as well, whereas the combinations of IL-1α with IL-1β or of TNF-β with TNF-β were not synergistic. Furthermore, granulocyte supernatant was synergistic with the combination of IL-1 and TNF, resulting in a more than 150-fold stimulation of PGE 2 production. Indomethacin completely suppressed these effects. We propose that granulocyte products acting together with IL-1 and TNF enhance PGE 2 synthesis during inflammation, and serve as signals for the initiation of preterm labor in the setting of intra-amniotic infection.
-
A product of activated human granulocytes stimulates prostaglandin E2 synthesis in human Amnion Cells.
Prostaglandins leukotrienes and essential fatty acids, 1991Co-Authors: K. Bry, M. HallmanAbstract:Abstract Cell-free supernatant from formylmethionyl-leucyl-phenylalanine (fMLP)-activated granulocytes causes a time- and concentration-dependent stimulation of prostaglandin E 2 (PGE 2 ) production in Amnion Cells. PGE 2 concentration in the culture medium after 36 h treatment with granulocyte supernatant (from 40 × 10 6 granulocytes/ml of Amnion Cell medium), 1.49 ± 0.71 pg/ng DNA (n = 13), was significantly higher (p = 0.0015) than in control Cells (0.33 ± 0.23 pg/ng DNA, n = 13). Indomethacin abolished this stimulation. Granulocyte supernatant and human epidermal growth factor (hEGF) had an additive effect on Amnion Cell PGE 2 production. Catalase, superoxide dismutase (SOD), protease inhibitors or the platelet-activating factor (PAF) antagonist L-659,989 had no effect. Actinomycin D, cycloheximide and mepacrine reduced the PGE 2 production. The phospholipase A 2 activity present in granulocyte supernatants was resistant to heating, whereas heating decreased their PGE 2 -stimulating activity by 92%. Exogenous phospholipase A 2 had no effect on PGE 2 synthesis. The granulocyte product could be precipitated with ammonium sulphate. On gel filtration of supernatant, two peaks of PGE 2 -synthesis stimulating activity were obtained (molecular weights 12 000 and 60 000). This data serve to explain the association of chorioAmnionitis with preterm labor: activated granulocytes release a protein(s) that induces prostaglandin production in Amnion Cells, and thus promote labor.
M. Hallman - One of the best experts on this subject based on the ideXlab platform.
-
Synergistic stimulation of Amnion Cell prostaglandin E2 synthesis by interleukin-1, tumor necrosis factor and products from activated human granulocytes.
Prostaglandins leukotrienes and essential fatty acids, 1991Co-Authors: K. Bry, M. HallmanAbstract:Abstract We examined the interactions between supernatant from FMLP-activated human granulocytes, recombinant interleukin-1 (IL-1) and recombinant tumor necrosis factor (TNF) in the stimulation of prostaglandin E 2 (PGE 2 ) production by human Amnion Cells. Amnion Cells from elective term cesarian sections were cultured in monolayer culture. Human granulocytes were activated with FMLP and centrifuged to obtain Cell-free supernatant. Amnion Cells were treated with granulocyte supernatant, IL-1α, IL-1β, TNF-α, TNF-β, or different combinations of these. Each of the stimulators alone enhanced the PGE 2 production 5-to 27-fold. Granulocyte supernatant was synergistic with each of the cytokines. The combinations of IL-1α or IL-1β with either TNF-α or TNF-β caused a synergistic stimulation of Amnion Cell PGE 2 production as well, whereas the combinations of IL-1α with IL-1β or of TNF-β with TNF-β were not synergistic. Furthermore, granulocyte supernatant was synergistic with the combination of IL-1 and TNF, resulting in a more than 150-fold stimulation of PGE 2 production. Indomethacin completely suppressed these effects. We propose that granulocyte products acting together with IL-1 and TNF enhance PGE 2 synthesis during inflammation, and serve as signals for the initiation of preterm labor in the setting of intra-amniotic infection.
-
A product of activated human granulocytes stimulates prostaglandin E2 synthesis in human Amnion Cells.
Prostaglandins leukotrienes and essential fatty acids, 1991Co-Authors: K. Bry, M. HallmanAbstract:Abstract Cell-free supernatant from formylmethionyl-leucyl-phenylalanine (fMLP)-activated granulocytes causes a time- and concentration-dependent stimulation of prostaglandin E 2 (PGE 2 ) production in Amnion Cells. PGE 2 concentration in the culture medium after 36 h treatment with granulocyte supernatant (from 40 × 10 6 granulocytes/ml of Amnion Cell medium), 1.49 ± 0.71 pg/ng DNA (n = 13), was significantly higher (p = 0.0015) than in control Cells (0.33 ± 0.23 pg/ng DNA, n = 13). Indomethacin abolished this stimulation. Granulocyte supernatant and human epidermal growth factor (hEGF) had an additive effect on Amnion Cell PGE 2 production. Catalase, superoxide dismutase (SOD), protease inhibitors or the platelet-activating factor (PAF) antagonist L-659,989 had no effect. Actinomycin D, cycloheximide and mepacrine reduced the PGE 2 production. The phospholipase A 2 activity present in granulocyte supernatants was resistant to heating, whereas heating decreased their PGE 2 -stimulating activity by 92%. Exogenous phospholipase A 2 had no effect on PGE 2 synthesis. The granulocyte product could be precipitated with ammonium sulphate. On gel filtration of supernatant, two peaks of PGE 2 -synthesis stimulating activity were obtained (molecular weights 12 000 and 60 000). This data serve to explain the association of chorioAmnionitis with preterm labor: activated granulocytes release a protein(s) that induces prostaglandin production in Amnion Cells, and thus promote labor.