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M W Flye

Publications and source records attributed to M W Flye.

At least 37 records · Page 2Linked to original sources
PubMed1998

Induction of donor-specific tolerance to rat nerve allografts with portal venous donor alloantigen and anti-ICAM-1/LFA-1 monoclonal antibodies.

BACKGROUND: Expendable autologous nerve available for repair of nerve injuries is limited. Cadaveric allografts could provide adequate nerve for grafting but are susceptible to rejection and currently require chronic systemic immunosuppression. METHODS: Age-matched Buffalo (RT1B) rats randomly assigned to 7 experimental groups received either a Lewis (RT1L) rat posterior tibial-sciatic nerve allograft or a Buffalo (RT1B) syngeneic isograft. Recipients were treated with anti-intercellular adhesion molecule-1 (anti-ICAM-1) and anti-leukocyte function-associated antigen-1 (anti-LFA-1) monoclonal antibodies (mAbs), intraportally administered ultraviolet B (UVB)-irradiated donor splenocytes, a combination of mAbs and UVB-irradiated donor splenocytes, or no immunosuppression. RESULTS: Histologic, electrophysiologic, and functional evaluation of nerve allografts 8 weeks after transplantation revealed a synergistic improvement in nerve allograft regeneration when monoclonal antibodies were combined with UVB-irradiated donor splenocytes. In vitro immunologic assessment correlated with the in vivo allograft function by demonstrating a donor-specific suppression of the recipient's response in mixed lymphocyte culture (MLC), cytotoxic T lymphocyte assay (CTL), and reduced T cell interleukin-2 production in both the group receiving UVB-irradiated alloantigen alone and the group receiving a combination of UVB antigen and mAbs. CONCLUSIONS: The combined use of mAbs directed against ICAM-1 and LFA-1 adhesion molecules with intraportally administered UVB modified donor antigen prevents nerve allograft rejection and synergistically improves nerve regeneration.

Animals↗
PubMed1997

In vitro analysis of gadolinium chloride abrogation of the systemic tolerance induced by portal venous administration of ultraviolet B-irradiated donor cells.

BACKGROUND: Normally, a Buffalo (BUF) recipient (RT1b) rejects a heterotopically transplanted Lewis (LEW) heart (RT1l) drained into the portal vein (PV) within 14 days. However, the addition of PV administration of 25x10(6) ultraviolet B (UVB)-treated LEW spleen cells (SC) to BUF recipients 7 days before cardiac transplantation results in 70% long-term allograft survival. METHODS: In this study, we used gadolinium chloride (GdCl3) (7 mg/kg/day) to selectively block the phagocytosis of recipient hepatic Kupffer cells before PV injection of UVB-treated donor SC to examine the mechanism of tolerance induction, as measured by in vitro analysis of mixed lymphocyte culture (MLC), T cell cytotoxicity, T helper cell precursors (pTH), and cytotoxic T cell precursors (pCTL) by limiting dilution analysis. RESULTS: A BUF recipient that received untreated or gamma-irradiated LEW SC intraportally reacted to in vitro stimulation by LEW alloantigen with increased MLC proliferation, T cell cytotoxicity, pTH and pCTL frequencies, and interleukin-2 production. In contrast, SC from BUF that received UVB-treated LEW SC were hyporesponsive on MLC stimulation by donor LEW alloantigen and exhibited markedly reduced cytotoxicity, pTH and pCTL frequency, and interleukin-2 production. However, normal in vitro responsiveness resulted with stimulation by third-party Brown-Norway (RT1n) SC, thus indicating that the systemic hyporesponsiveness was specific for the UVB donor alloantigen given PV. On the other hand, GdCl3 given by intravenous injection daily for 3 days before PV alloantigen blocked the induction of in vitro hyporesponsiveness. CONCLUSION: Therefore, prevention of alloantigen sequestration by GdCl3 inhibition of hepatic Kupffer cell phagocytosis was pivotal in preventing the development of portal venous tolerance.

Animals↗
PubMed1997

Evidence for clonal deletion and clonal anergy after intrathymic antigen injection in a transplantation model.

Intrathymic (IT) antigen injection has been shown to induce antigen-specific systemic tolerance in the rodent. To delineate the mechanisms responsible for the induction of tolerance, we used the 2C line of T cell receptor transgenic mice. The majority of T cells in 2C mice express an antigen receptor specific for the major histocompatibility complex class I alloantigen Ld and can be identified with the clonotypic monoclonal antibody 1B2. IT injection of lymphoid cells expressing Ld was found to induce a significant prolongation in BALB/c skin allograft survival. The allograft prolongation was associated with a marked reduction in the number of developing 1B2+ thymocytes (clonal deletion), which occurred primarily at the CD4+ CD8+ stage of thymocyte development, as well as a reduction in the number of mature CD8+ 1B2+ 2C T cells in peripheral lymphoid tissue. In addition, CD8+ 1B2+ 2C T cells that survive deletion have decreased CD8 expression levels and a significantly reduced in vitro proliferative response to specific alloantigen (clonal anergy). Exogenous recombinant interleukin 2 restores the capacity of 2C T cells to respond in vitro to alloantigen. Experiments involving separation of cells by fluorescence-activated cell sorter indicate that there is a precise correlation between the reduction in CD8 expression and anergy induction. Collectively, these data indicate that IT antigen injection can induce antigen-specific systemic tolerance by both clonal deletion and clonal anergy.

Adoptive Transfer↗
PubMed1997

Therapeutic levels of functional human factor X in rats after retroviral-mediated hepatic gene therapy.

Factor X deficiency results in a rare but serious bleeding disorder that might be treated by expressing a normal factor X gene in patients. We generated an amphotropic retroviral vector with the human FX cDNA and delivered it to rat hepatocytes in vivo during liver regeneration. The human alpha1-antitrypsin promoter was chosen to direct expression because it was the most efficient of several tested in yielding expression of alpha1-antitrypsin protein from a retroviral vector in hepatocytes in vivo. We achieved expression of factor X in four rats at levels sufficient to maintain hemostasis in humans (10% to 43% of normal). The factor X was determined to be functional by using a chromogenic substrate assay after immunoprecipitation with human specific antibodies. Expression of factor X remained stable for more than 10 months in two rats. It is likely that expression will be maintained for the life of the animals, because retroviral vectors integrate into the chromosome and hepatocytes are long-lived. The high and stable levels of expression achieved using this liver-specific promoter overcomes one of the two major obstacles to successful human gene therapy for hemophilia.

3T3 Cells↗
PubMed1997

Rejection of spontaneously accepted rat liver allografts with recipientinterleukin-2 treatment or donor irradiation.

While MHC incompatible DA (RTl(a)) to Lewis (RT1(1), LEW) rat liver allografts are acutely rejected, the reciprocal LEW to DA liver grafts are spontaneously accepted. The mechanism of this acceptance remains unclear. We evaluated the effect of donor treatment with total body irradiation (TBI) or gadolinium chloride (GdCl3), and recipient treatment with exogenous IL-2 after transplantation on the survival of the spontaneously accepted liver grafts. Male LEW and DA rats were used as donors and recipients for orthotopic liver allo- or iso-graft transplants. The LEW liver donor was treated by TBI (10 gray) 7 days before transplantation, or LEW donor Kupffer cell phagocytosis was blocked with GdCl3 (7 mg/kg) on days -2 and -1 pretransplant. In an attempt to reverse LEW liver graft acceptance, 180,000 units human IL-2 (hIL-2) were administered daily IP to the DA liver recipients from days 1 to 7 after liver grafting. While untreated LEW recipients rejected DA liver grafts within 13 days, DA recipients accepted LEW livers indefinitely (>302 days). In contrast, irradiation of the LEW liver donor prevented the spontaneous acceptance by DA recipients, and resulted in acute rejection of the liver grafts in 9-20 days. However, spontaneous graft tolerance was restored by parking the irradiated LEW donor liver in naive LEW rats for 48 hr before retransplantation to DA recipients (>50 days). When LEW donors were treated with GdCl3, which is known to block Kupffer cell phagocytosis and antigen processing, the spontaneous acceptance of the LEW liver grafts by DA recipients was unaffected. However, when exogenous rhIL-2 was given daily, LEW liver allografts were rejected by the DA recipients. The resulting liver failure correlated with a progressive increase in serum bilirubin and the development of a predominantly lymphocytic portal tract infiltration, bile duct epithelial damage, and portal vein endothelitis, which is consistent with acute allograft rejection. LEW and DA recipients of liver isografts developed no toxicity and survived indefinitely (>100 days) when treated with the same dose of IL-2. These results indicate that spontaneous rat liver allograft acceptance is associated with the presence of radiosensitive cells in the donor liver that may interact with recipient T cells to inhibit (Th1) production of IL-2.

Animals↗
PubMed1997

Induction of donor specific transplantation tolerance to cardiac allografts following treatment with nondepleting (RIB 5/2) or depleting (OX-38) anti-CD4 mAb plus intrathymic or intravenous donor alloantigen.

The nondepleting monoclonal antirat CD4 antibody, RIB 5/2, has been shown to modulate, but not eliminate, the CD4+ T cells and to prolong survival of rat skin, renal, or cardiac allografts when serially administered after transplantation. In the present study, we compared the efficacy of recipient pretreatment with a single dose of nondepleting RIB 5/2 or depleting OX-38 anti-CD4 monoclonal antibody plus donor alloantigen given intravenously or intrathymically 21 days before transplantation on the survival of completely MHC-mismatched rat cardiac allografts. Intraperitoneal injection of a single dose (20 mg/kg) of RIB 5/2 resulted in a decrease in CD4 surface molecule expression on peripheral CD4+ T cells without cell elimination as shown by FACS analysis. The nonspecific effect of a single dose of RIB 5/2 mAb had resolved by 21 days after treatment as evidenced by the almost complete recovery of normal surface CD4 molecule expression. Cardiac allografts transplanted immediately or 21 days after a single dose of RIB 5/2 alone were uniformly acutely rejected. On the other hand, recipients treated with depleting anti-CD4 OX-38 (20 mg/kg) acutely rejected cardiac allografts transplanted 21 days later, but indefinitely accepted all grafts transplanted on the same day. In contrast, combined treatment with i.v. donor splenocytes (25 x 10(6)) plus nondepleting RIB 5/2, but not with depleting anti-CD4 mAb, OX-38, resulted in survival for more than 100 days in 75% of recipients of donor specific, but not third party, cardiac allografts transplanted 21 days later. Irradiation (3000 rads) of the i.v. donor splenocytes combined with RIB 5/2 abrogated their tolerizing effect. When donor antigen was given intrathymically, both RIB 5/2 and OX-38 resulted in indefinite tolerance to cardiac allografts transplanted 21 days later. The failure of exogenous administration of high dose (180,000 IU/injection) rIL-2 for 10 days to reverse the unresponsiveness of i.v. SC plus RIB 5/2 pretreatment suggests that this tolerant state is not due to a deficiency of IL-2. In vitro studies showed marked inhibition of MLC responsiveness and cytolytic T cell activity in tolerant recipients that cannot be reversed by the addition of IL-2. Thus, pretransplant intravenous donor alloantigen combined with a dose of nondepleting anti-CD4 mAb, RIB 5/2, which alone has no significant effect, induced donor specific cardiac allograft tolerance.

Animals↗
PubMed1997

Tolerance to heart and kidney grafts induced by nondepleting anti-CD4 monoclonal antibody (RIB 5/2) versus depleting anti-CD4 monoclonal antibody (OX-38) with donor antigen administration.

BACKGROUND: The monoclonal antirat CD4 antibody RIB 5/2 has been shown to modulate the CD4 glycoprotein without eliminating the affected T cells. We have shown that the administration of multiple doses of RIB 5/2 during the peritransplantation period prevents the rejection of rat kidney allografts. METHODS: We compared the efficacy of a single intraperitoneal dose of 20 mg/kg RIB 5/2 plus donor antigen (25 x 10(6) spleen cells [SCs]) given by either an intrathymic or an intravenous route with the depleting anti-CD4 monoclonal antibody (mAb) OX-38 plus antigen 21 days before a major histocompatibility complex (MHC)-mismatched Lewis (RT1l) to Buffalo (RT1b) rat cardiac or renal allograft. By delaying the transplantation for 21 days, recovery from the nonspecific effects of the antibody treatment allowed the demonstration of donor antigen-specific tolerance. RESULTS: OX-38 mAb given with intrathymic SCs induced tolerance to heart but not kidney grafts, whereas OX-38 given with intravenous SCs failed to prolong survival of either heart or renal allografts. In contrast, RIB 5/2 mAb administration, when combined with alloantigen given by either intravenous or intrathymic routes, induced tolerance to heart allografts, whereas only alloantigen given by the intravenous route with RIB 5/2 resulted in tolerance to renal grafts. CONCLUSIONS: Concomitant administration of intravenous donor alloantigen and the modulation of CD4+ recipIent cells by nondepleting RIB 5/2, rather than elimination of these CD4+ cells with depleting mAb OX-38, is a more potent method for the induction of allograft tolerance.

Animals↗
PubMed1997

Radical resection of tumors of the inferior vena cava with vascular reconstruction and kidney autotransplantation.

BACKGROUND: Tumors of the inferior vena cava (IVC) are rare tumors. Although often locally confined, juxtaposed vital structures usually limit the extent of resection. However, complete surgical resection has been shown to be the most important positive prognostic factor. METHODS: Four patients had resection of primary vena caval tumors. In two patients with locally extensive vena caval tumors the limits of conventional resection were extended by means of complete resection of the involved infrahepatic IVC, aorta, and both kidneys. The IVC and aorta were reconstructed with synthetic grafts, and the uninvolved kidney was autotransplanted for both patients. RESULTS: Of the two patients treated with more extensive resection, one patient had no evidence of disease 26 months after operation, and the second patient died of recurrent disease 23 months after operation. CONCLUSIONS: Primary tumors of the IVC may extend locally without distant metastasis. Radical surgical excision as the primary mode of treatment provides the best chance for prolonged survival in appropriately selected patients with tumors of the IVC. After surgical excision the patient with the leiomyosarcoma was treated with radiation therapy and the patient with rhabdomyosarcoma by chemotherapy. Although leiomyosarcomas of the IVC are rare tumors, the first patient is only the third reported case of the even rarer rhabdomyosarcoma of the IVC.

Adult↗
PubMed1997

Spontaneous closure of selected iatrogenic pseudoaneurysms and arteriovenous fistulae.

PURPOSE: We report our approach to the management of postcatheterization femoral artery pseudoaneurysms and arteriovenous fistulae in an attempt to determine the frequency of spontaneous resolution of selected lesions. METHODS: We studied 196 pseudoaneurysms, 81 arteriovenous fistulae, and 9 combined lesions that were identified by duplex scan. Indications for immediate surgical repair included pseudoaneurysm greater than 3 cm, enlarging hematoma, pain, groin infection, nerve compression, limb ischemia, concomitant surgical procedure, and patient refusal or inability to comply with follow-up. All other lesions were observed. RESULTS: One hundred thirty-nine patients underwent prompt surgical repair, and 147 patients were initially managed without operation. There were no limb-threatening complications associated with nonoperative management in this subset of patients. Eighty-six percent of the lesions being observed resolved spontaneously within a mean of 23 days, whereas 14% required surgical closure for a variety of reasons (at a mean of 111 days after the initial diagnosis). There was no statistically significant difference in the rate of spontaneous pseudoaneurysm closure (89%) as opposed to fistulae (81%) (p < 0.17). By life-table analysis, 90% of selected pseudoaneurysms had resolved by 2 months. Patients selected for observation underwent an average of 2.6 duplex scans per patient versus 1.4 scans per patient for those treated with immediate surgery (p < 0.01). CONCLUSION: The natural history of stable pseudoaneurysms and arteriovenous fistulae is benign and frequently results in spontaneous resolution, which allows properly selected patients to be managed without operation.

Analysis of Variance↗
PubMed1997

Calcium antagonists inhibit oxidative burst and nitrite formation in lipopolysaccharide-stimulated rat peritoneal macrophages.

Activated macrophages are important cell effectors in sepsis/endotoxemia. Superoxide (SO) and nitric oxide (NO) are produced by activated macrophages and are responsible for host defense against microorganisms. Using laser scanning confocal microscopy, we investigated the role of intracellular free calcium ([Ca2+]i) on SO and NO production by rat peritoneal macrophages activated by lipopolysaccharide (LPS). Calcium influx from the extracellular space versus release of calcium from intracellular stores was determined using calcium channel blockers (diltiazem [DIL], verapamil [VER], and nicardipine [NIC]) and dantrolene (DAN), respectively. Cells incubated with LPS had a 30-50 nM increase in [Ca2+]i, (p < .05) compared with non-LPS-treated cells. When stimulated with phorbol myristate acetate, both control and LPS-treated cells sustained a comparable increase in [Ca2+]i, but [Ca2+]i, remained elevated 30 min later in LPS-treated cells. Calcium channel blockers and DAN reduced phorbol myristate acetate-stimulated SO and LPS-stimulated NO production at all concentrations tested (p < .05). Although increased extracellular calcium influx and calcium from intracellular stores are important regulators of SO and NO production in macrophages, extracellular calcium influx seems to have the predominant effect. Calcium antagonists may modulate the inflammatory response via their effects on macrophages.

Animals↗
PubMed1997

Allograft infiltrating cytotoxic T lymphocytes recognize kidney-specific human minor histocompatibility antigens.

The role of minor histocompatibility antigens (mH) in allograft immunity has been proposed, but the nature of these antigens and their immunogenicity are not well understood. We have shown that tissue-specific cytolytic T lymphocytes (CTL) can be isolated form graft infiltrating lymphocyte (GIL) populations from renal transplant recipients undergoing acute cellular rejection. In most cases these CTL were allorestricted recognizing donor mismatched kidney MHC class I antigens. In contrast, one patient's GIL T cells demonstrated specific lytic activity against HLA-B35 expressed on primary kidney epithelial cell lines (KCL) but not on B-lymphoblastoid cell lines (LCL). Since HLA-B35 was a shared antigen between donor and recipient, these results suggest that CTL within the GIL population are recognizing a tissue-specific minor histocompatibility antigen presented in the context of self-HLA-B35.

Acute Disease↗
PubMed1996

Portal branch occlusion safely facilitates in vivo retroviral vector transduction of rat liver.

Hepatic gene therapy might correct the clinical manifestations of several genetic disorders in patients. Although retroviral vectors with a strong liver-specific promoter can result in stable and therapeutic levels of expression of genes from the liver, application of these techniques in humans is limited by the need to perform one or more invasive procedures to achieve ex vivo or in vivo transduction of hepatocytes. In vivo delivery involves injection of retrovirus into the portal vein during liver regeneration. Although transduction is efficient and specific for the liver, induction of hepatocyte replication requires a 70% partial hepatectomy or administration of a liver toxin. An alternative method for inducing hepatocyte replication is to occlude branches of the portal vein. This results in apoptosis of hepatocytes in the occluded lobes and compensatory replication of the hepatocytes in the nonoccluded lobes. We demonstrate here that portal branch occlusion is nearly as effective as partial hepatectomy at facilitating retroviral vector transduction in vivo and has a lower morbidity. Portal branch occlusion could be performed in larger animals by minimally invasive techniques and has been used safely to treat human patients with liver cancer. Portal branch occlusion might ultimately be used in humans to facilitate retroviral vector transduction in vivo for the treatment of genetic diseases.

Alanine Transaminase↗
PubMed1996

Inhibition by CTLA4Ig of experimental allergic encephalomyelitis.

B7-1 and B7-2 are well characterized costimulatory ligands on Ag presentation cells for the CD28 and CTLA4 receptors on T cells. The fusion protein CTLA4Ig can block this interaction and prevent specific T cell activation. The development of fatal CD4+ T cell-mediated experimental allergic encephalomyelitis (EAE) in susceptible female Lewis rats was optimized by immunization with 20 mg of guinea pig spinal cord homogenate in CFA on day 0 with three doses of 1 microgram pertussis toxin given i.v. on days 0, 3, and 7. This immunization regimen uniformly resulted in the development of severe clinical neurologic signs of EAE with 100% mortality by day 17 postimmunization. Treatment with 0.5 mg/dose of rhCTLA4-Ig on days - 2, 0, 3, 6, 9, 12, 15 and 18 significantly decreased the incidence, delayed the onset, and reduced the severity of clinical EAE (p = 0.0002 vs control by the Mann-Whitney U test) enough to completely prevent fatal EAE, whereas treatment with control human IgG had no effect. Histologically, perivascular neutrophilic infiltrates were also dramatically decreased in the spinal cords of animals treated with CTLA4 but not in those treated with control human IgG. The proliferative response to encephalitogenic Ags (guinea pig myelin basic protein and proteolipid protein) by lymph node cells from animals immunized with guinea pig spinal cord 10 days before was also significantly suppressed in vitro by CTLA4Ig (1 microg/ml). However, the protective effect of CTLA4Ig could be completely prevented by the daily i.p. administration, from day 0 to 10, of exogenous human rIL-2 (180,000 IU). These results indicate a critical requirement of the costimulatory B7/CD28 pathway early in the development of CD4+ T cell-mediated EAE in the rat.

Abatacept↗
PubMed1996

Liver-directed gene therapy: a retroviral vector with a complete LTR and the ApoE enhancer-alpha 1-antitrypsin promoter dramatically increases expression of human alpha 1-antitrypsin in vivo.

Hepatic gene therapy could improve the treatment of many inherited disorders. Although retroviral vectors result in long-term expression in hepatocytes in vivo, their low level of expression currently precludes most clinical applications. Four copies of the liver-specific apolipoprotein E (ApoE) enhancer were placed upstream of the human alpha 1-antitrypsin (hAAT) promoter in either orientation into a retroviral vector with a complete long terminal repeat (LTR) and the hAAT cDNA to generate ApoE(+)hAAT-LTR and ApoE(-)hAAT-LTR. In addition, the ApoAI promoter was placed upstream of the hAAT cDNA in a similar retroviral vector backbone. Amphotropic retroviral vectors were transferred into regenerating rat liver cells in vivo by intraportal injection. ApoE(-)hAAT-LTR and ApoE(+)hAAT-LTR led to average hAAT levels of 5 micrograms/ml (0.5% of normal levels of a very abundant protein), and 2.5 micrograms/ml, respectively, which was stable for at least 10 months after transduction. This level of serum hAAT was > 25-fold higher than what was observed from the ApoAI promoter used in this study. Serum levels of hAAT were > 15-fold higher than what was observed from retroviral vectors containing the hAAT cDNA that were analyzed previously by this lab. In some cases, improved expression was due to the promoter chosen. In other cases, the increase in expression was primarily due to the higher titers obtained by using a retroviral backbone with an intact LTR as opposed to a vector with a deletion in the LTR. The increased expression levels observed from this enhancer/promoter combination in an intact retroviral backbone may enable one to achieve therapeutic levels of clinically important genes from a retroviral vector in liver cells of animals.

Animals↗
PubMed1996

Successful transfer of immune unresponsiveness to concordant rat islet xenografts.

Indefinite survival of concordant xenogeneic Wistar Furth (WF) rat islet survival was obtained by intrahepatic transplants of cultured WF islets and a single injection of antilymphocyte sera in C57BL/6 mice. Adoptive transfer of splenocytes from mice with established WF islet xenografts produced a marked prolongation of survival of WF islets transplanted under the kidney capsule of diabetic irradiated (600 rads), naive C57BL/6 recipients (mean survival time = 48.9 +/- 17.1 days), and three of the recipients were still normoglycemic at 100 days after transplantation. Adoptive transfer of an equal mixture (3 x 10(7) cells each) of these splenocytes with normal splenocytes also prolonged survival of the kidney capsule islet xenografts (mean survival time = 26.5 +/- 7.8 days vs. 15.2 +/- 5.3 days for controls). In vitro studies on lymphocyte proliferation demonstrated a low rate of proliferation of splenocytes from established islet xenografts in the presence of irradiated WF splenocytes (stimulation index = 1.6 vs. 16.2 for naive C57Bl/6 mice), and mixing the cells with control splenocytes also decreased the proliferation of splenocytes as compared with controls (stimulation index = 5.4 vs. 16.2 in controls). The inhibitory effect was not species specific, since splenocytes from mice with established islet xenografts also produced a 42% inhibition of proliferation in the presence of irradiated Lewis splenocytes. These findings demonstrate that concordant, islet xenograft, immune unresponsiveness can be adoptively transferred by splencotyes from mice with established islet xenografts.

Animals↗
PubMed1996

Depressed splenic function after hemorrhage results from gastrointestinal tract stimulation of hepatic-mediator release. Correction with portacaval shunt.

OBJECTIVE: To determine whether redirecting intestinal blood flow away from the liver via a portacaval shunt would protect distal immune responses in the spleen after hemorrhage. DESIGN: Type C3H/HeN male mice in which a portacaval shunt had been established 2 to 3 weeks before the experiment were bled, their blood pressure was maintained at 35 mm Hg for 1 hour, and then they were resuscitated. Twenty-four hours later, the mice were killed, and mixed and adherent splenocyte cultures were established. The proliferative capacity of splenocytes, the release of interleukin-2 and interleukin-4, and the ability of splenic macrophages to present the antigen, conalbumin, were then determined as indexes of immunocompetence. RESULTS AND CONCLUSIONS: The results indicate that splenocyte proliferation and splenocyte interleukin-2, but not interleukin-4, release were decreased and that splenic macrophage antigen presentation declined after hemorrhage. However, animals in which a portacaval shunt had been established before hemorrhage showed no such changes in their splenocyte or splenic macrophage functions. Thus, the decline of splenic immune responses after hemorrhage seems to be due to mediators released from the gut. Such mediators, in turn, stimulate Kupffer cells to secrete additional agents that produce immunosuppressive exocrine effects on splenic immune functions.

Animals↗
PubMed1996

Alterations in enzymatic functions in hepatocytes and hepatocellular carcinomas from Ras-transduced livers resemble the effects of insulin.

An understanding of how oncogenes affect differentiated liver functions might lead to improved treatments for liver cancer or other disorders where liver-specific functions are compromised. A retroviral vector that coexpressed beta-galactosidase (beta-gal) and activated Ras genes (Ras-gal) was transduced into a small fraction of adult rat hepatocytes in vivo. Hepatocytes from Ras-gal-transduced diethylnitrosamine-untreated livers and hepatocellular carcinomas (HCC) from Ras-gal-transduced diethylnitrosamine-treated rats were analyzed for liver functions by performing histochemical assays on liver sections. Ras-gal-transduced hepatocytes failed to express gluconeogenic, ketogenic, and urea pathway enzymes. In contrast, several enzymes involved in fat synthesis were strongly activated, and microvesicular fat accumulated. These metabolic changes are induced in normal livers by insulin, a hormone that activates p21-ras. The deregulation of p21-ras may inhibit these liver-specific functions and may induce fat synthesis in both malignant and nonmalignant liver diseases. Furthermore, treatment with drugs that inhibit the attachment of p21-ras to the plasma membrane might reverse these changes. The alterations in enzymatic functions in the HCCs were similar to those observed in the hepatocytes, although each of the two cancers had a region that abruptly lost its expression of liver-specific enzymes and acquired the expression of genes that are more characteristic of oval or bile ductule cells. This suggests that a single genetic event in a malignant cell may dramatically alter its apparent phenotype. The identification of this putative gene might lead to insights into the regulation of the phenotype of normal cells in the liver.

3T3 Cells↗