ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.The potential therapeutic benefits of CD3 monoclonal antibodies, such as OKT3, have been limited by their immunogenicity and their propensity to activate a severe cytokine release syndrome. This has constrained the clinical use of OKT3 to the treatment of acute rejection episodes of organ allografts.Methods.We have humanized a rat CD3 antibody and created a single amino acid substitution in position 297 of the IgG1 heavy chain to prevent glycosylation and, consequently, binding of the therapeutic antibody to Fc receptors and to complement. This antibody has been given as first line antirejection therapy in nine kidney transplant recipients with biopsy-proven acute rejection episodes.Results.None of the patients demonstrated any antiglobulin response nor any significant cytokine release syndrome. Seven of the nine showed evidence of resolution of their rejection, although some patients experienced re-rejection.Conclusions.These findings suggest that CD3 antibodies can be engineered to lose their toxicity while retaining their potency as immunosuppressants. Non-activating humanized CD3 monoclonal antibodies now merit further investigation in the management of transplant patients and in therapy of autoimmune diseases.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.A major step in translating work on laryngeal transplantation into clinical practice is the establishment of a preclinical model. We have investigated the anatomy and mucosal immunology of the porcine larynx in eight Minnesota Minipigs (12-37 weeks).Methods.Neck dissections were carried out and the vascular tree was mapped. Snap-frozen biopsies from epiglottis, supraglottis, glottis, and subglottis were prepared for conventional histology, immunohistochemistry (CD45), and single and two-color immunofluorescence (CD3, MHC-II, CD45).Results.The anatomy of the laryngeal skeleton was broadly similar to that of the human larynx. The blood supply is predominantly via the caudal thyroid vessels, with assistance from the cranial laryngeal artery. The porcine larynx is clearly highly immunologically active. Structured collections of leukocytes were found in the mucosal epithelium, around tubuloacinar glands, and occasionally in the submucosa. MHC-II and CD 3 cells were predominantly found within the epithelium. The highest densities of all cell types were observed in the epiglottis, tailing off caudally. The lowest densities were seen in the vocal cords.Conclusions.The porcine larynx is both anatomically and immunologically similar to the human larynx and contains a high level of immunological organization. It presents an ideal preclinical model for laryngeal transplantation.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.The present study was undertaken to determine whether anti-complement 5 (C5) monoclonal antibodies (mAb) prevent hyperacute rejection (HAR) in a rat-to-presensitized mouse heart transplantation model and whether these mAb, combined with cyclosporine (CsA) and cyclophosphamide (CyP), can achieve long-term graft survival.Methods.BALB/c mice were presensitized with 2×107splenocytes from Lewis rats 14 days before grafting. Heart grafts from Lewis rats were heterotopically transplanted into BALB/c mice. Presensitized mice were treated with either anti-C5 mAb or a combination of anti-C5 mAb, CsA, and CyP. Controls included: presensitized mice with no treatment, presensitized mice treated with either CsA + CyP or IgG, and nonpresensitized mice with either no treatment or with CsA + CyP treatment.Results.Although typical features of HAR were evident in the presensitized grafts, the mAb completely inhibited complement activation and successfully prevented HAR. Despite complement inactivation, the graft was rejected on postoperative day 6 with acute vascular rejection (AVR) also known as delayed xenograft rejection (DXR). Notably, this type of rejection cannot be effectively overcome by CsA and CyP.Conclusions.We conclude that (1) anti-C5 mAb prevents HAR, (2) AVR/DXR still occurs when HAR is prevented by complement inactivation, and (3) AVR/DXR cannot be overcome by conventional immunosuppression. These data suggest that anti-C5 mAb may be valuable for preventing HAR in future clinical xenotransplantation and that additional interventions may be required to address AVR/DXR.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.Cyclosporine (CsA) is an essential post-transplantation immunosuppressive drug. It may cause hepatotoxicity, mostly cholestasis, by unknown mechanism. CsA causes nephrotoxicity mainly by increased vascular resistance. We investigated the effects of CsA on the peribiliary capillary plexus, in an isolated, dually perfused (i.e., via the hepatic artery and the portal vein) rat liver preparation.Methods.After 30 min of stabilization with optimal flow (4 ml/min/g liver), four liver groups were perfused (control, n=5 each) and four groups were hypoperfused (n=5 each, 1 ml/min/g) for 120 min. This was followed by a 30-min optimal reperfusion phase, during which the controls and the hypoperfused groups were injected (60 sec) via the hepatic artery with CsA at high (3 mg/kg body weight in 1 ml) or low dose (0.03 mg/kg), cremophore (130 mg/kg), or saline (1 ml). A ninth group (n=5) underwent 2-hr ischemia and 30-min reperfusion to standardize liver damage. Dark nonradioactive microspheres (∼10 μm diameter) were injected via the hepatic artery 15 min after drug or saline injection.Results.Neither of the two CsA doses, nor cremophore controls, nor hypoperfusion alone caused entrapment of microspheres in the peribiliary circulation as assessed by light microscopy; perfusion pressures and resistances were also not altered. Significant arteriolar impaction and vasculature engorgement occurred in the hypoperfused plus high-dose CsA livers; hypoperfusion plus low-dose CsA or cremophore groups were minimally tainted. Vascular notable obstruction was associated with 15-40% increase in portal and arterial perfusion pressures and resistances, 50% decrease in oxygen extraction, and increase in lactate/pyruvate ratio, hepatocellular damage, and wet-to-dry weight ratio. Such findings were superior to those detected in the ischemic livers.Conclusions.Acute single high-dose CsA injection, but not low-dose or cremophore, if combined with decreased flow, alters hepatic microcirculatory resistance. Possible correlations between such changes and clinical implications in organ transplantation are discussed.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.Day of transplant T cell depletion with anti-CD3 immunotoxin or F(Ab)2immunotoxin induces stable tolerance to renal allografts in rhesus monkeys given 15-deoxyspergualin (DSG), a NF-κB inhibitor that suppresses proinflammatory cytokine (PC) production. Because PC and NF-κB are involved in dendritic cell (DC) maturation, we asked if impaired DC maturation and Th2-type cytokine deviation might be related to the synergistic effect of DSG in this novel model.Methods.Immunosuppression was initiated 4 hr before transplanting a major histocompatibility complex mismatched renal allograft. Some groups received a supplemental 5-day course of cyclosporine A or DSG or a 15-day course of DSG. Peripheral lymph nodes were sequentially examined for presence of mature DC. In vitro effects of DSG on PC-induced maturation of DC were also examined.Results.Allografts survived without rejection in 87% of recipients given immunotoxin or F(Ab)2immunotoxin with DSG × 15 days, in 50% with DSG × 5 days, and 0% with cyclosporine A. The longest DSG survivors are >1000 days with normal graft function and tolerance validated, including acceptance of challenge second donor kidneys without treatment. DSG-treated recipients were unique in developing polarized Th2-type plasma cytokines. In DSG recipients, mature DC were significantly reduced in day +5 lymph node biopsies, with complete repopulation by 30 days. In vitro studies verified an inhibitory effect of DSG on DC maturation.Conclusions.The study suggests DSG arrests DC maturation. The unusual synergy of immunotoxin and DSG apparently involves coincidental reduction in lymph node T cell mass and mature DC, a transient circumstance favoring development of stable tolerance.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.Porcine fetal pancreas is a potential source of β cells for transplantation. The immaturity of the cells is a problem. We have defined the optimal conditions for in vitro propagation of this tissue before transplantation.Methods.Porcine fetal pancreas tissue was obtained for tissue culture at various stages of development. Serum-containing and serum-free media and a variety of potential differentiation factors were tested. In vitro, the numbers of endocrine islet cells and their proliferation were quantified and functional maturity of the β cells was assessed by perifusion. Growth and maturation of the cells was assessed 3 months after transplantation into nude mice.Results.Highest β cell mass was obtained from end-gestational, as compared with early fetal or neonatal, pancreas. Nicotinamide and sodium butyrate effectively increased the insulin content and the number of endocrine cells in culture. In combination, these factors led up to a 90-fold increase in the insulin content of islet-like cell clusters (ICC) as compared with untreated controls. However, a high level of cell death through apoptosis was observed in these maximally stimulated endocrine cells, and they did not survive as grafts when transplanted into nude mice. Instead, a serum-free culture medium containing 10 mM nicotinamide and 0.1 mM isobutylmethylxanthine was found to support both differentiation and proliferation of endocrine cells as loose ICCs. Insulin release from these ICCs was sensitive to glucose. When transplanted under the kidney capsule of normoglycemic nude mice, a high level of β cell differentiation and function was evident only in the ICCs cultured in the serum-free medium, and in freshly isolated ICCs. When transplanted to hyperglycemic nude recipients, the cells cultured in serum-free medium for 3 weeks reversed hyperglycemia more consistently and rapidly than freshly isolated ICCs.Conclusions:.Optimal maturation of porcine fetal pancreatic cells is obtained in serum-free medium supplemented with nicotinamide. Butyrate is a potent stimulus for β cell differentiation but leads to increased apoptotic cell death.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID