An easy and reproducible model of kidney transplantation in rats.

Objective: Kidney transplantation in rats is an important research model. Various methods have been reported, but there is no "standard operation." We investigated a 1-stage versus a 2-stage native nephrectomy and the type of ureteral anastomosis seeking to establish a standard, reproducible and successful method.

Aminoacyl-tRNA synthetase inhibitors as potent and synergistic immunosuppressants.

The aminoacyl-tRNA synthetase family of enzymes is the target of many antibacterials and inhibitors of eukaryotic hyperproliferation. In screening analogues of 5'-O-(N-L-aminoacyl)-sulfamoyladenosine containing all 20 proteinogenic amino acids, we found these compounds to have potent immunosuppressive activity. Also, we found that combinations of these compounds inhibited the immune response synergistically.

Occurrence of autoimmunity after xenothymus transplantation in T-cell-deficient mice depends on the thymus transplant technique.

Xenothymus transplantation under the kidney capsule in athymic rodents frequently leads to multiorgan autoimmunity. Herein, we explore whether this is an intrinsic risk of xenothymus grafting or whether it depends on the transplant technique. We developed a new technique of "venous pouch" thymus grafting (heart-xenothymus) and compared this with the conventional kidney subcapsular technique (kidney-xenothymus) in a rat-into-nude-mouse model.

Rapidly induced, T-cell independent xenoantibody production is mediated by marginal zone B cells and requires help from NK cells.

Xenoantibody production directed at a wide variety of T lymphocyte-dependent and T lymphocyte-independent xenoantigens remains the major immunologic obstacle for successful xenotransplantation. The B lymphocyte subpopulations and their helper factors, involved in T-cell-independent xenoantibody production are only partially understood, and their identification will contribute to the clinical applicability of xenotransplantation. Here we show, using models involving T-cell-deficient athymic recipient mice, that rapidly induced, T-cell-independent xenoantibody production is mediated by marginal zone B lymphocytes and requires help from natural killer (NK) cells.

CTLA-4 blockade in murine bone marrow chimeras induces a host-derived antileukemic effect without graft-versus-host disease.

We studied the effect of CTLA-4 blockade on graft-versus-leukemia and graft-versus-host responses in a mouse model of minor histocompatibility-mismatched bone marrow transplantation. Early CTLA-4 blockade induced acute graft-versus-host disease. Delayed CTLA-4 blockade resulted in a lethal condition with lymphosplenomegaly, but with stable mixed T-cell chimerism, unchanged alloreactive T-cell frequencies and absent anti-host reactivity in vitro.

Induction and maintenance of T-dependent or T-independent xenotolerance by nonprimarily-vascularized skin or thymus grafts.

Background: The success of clinical xenotransplantation will depend on induction of xenotolerance. We have previously shown that combined xenothymus and vascularized xenoheart transplantation under the coverage of a tolerizing regimen (TR) can induce and maintain full xenotolerance. Here, induction/maintenance of xenotolerance using nonprimarily-vascularized thymus and/or skin grafts was investigated.

Effects of a short course of leflunomide on T-independent B-lymphocyte xenoreactivity and on susceptibility of xenografts to acute or chronic rejection.

Background: Leflunomide is a novel immunosuppressive agent with promising activity for xenotransplantation. It is not clear yet which mechanisms of action of leflunomide are responsible for that.

Methods: In a hamster-to-C57BL/6 nude mouse heart transplantation model, a 2-week course of leflunomide was used after transplantation or for pretreating donors.

Pathogenesis of autoimmunity after xenogeneic thymus transplantation.

Thymus transplantation is a promising strategy to induce xenotolerance, but may also induce an autoimmune syndrome (AIS). The pathogenesis of this AIS was explored using nude rats as recipients. Thymus grafts consisted of fetal hamster thymic tissue with or without mixing with fetal rat tissue such as thymus, thyroid, salivary gland, and heart.

Transforming growth factor-beta inhibits lymphokine activated killer cytotoxicity of bone marrow cells: implications for the graft-versus-leukemia effect in irradiation allogeneic bone marrow chimeras.

Background: We have previously shown that allogeneic bone marrow (BM) chimeras preconditioned with total lymphoid irradiation and low-dose total body irradiation (TLI/TBI) develop a stronger graft-versus-leukemia (GVL) effect than chimeras preconditioned with high-dose total body irradiation only (TBI). Here, we report on the possible role of cytokines in the mechanism underlying this GVL effect.

Methods: Splenic mRNA levels of the cytokines interleukin (IL)-1, IL-2, IL-4, IL-6, IL-7, IL-10, IL-12, IL-15, interferon-gamma, tumor necrosis factor-alpha, and transforming growth factor-beta (TGF-beta), and of inducible nitric oxide synthetase were determined by reverse transcription-polymerase chain reaction in TLI/TBI- or TBI-conditioned C3H/AKR BM chimeras challenged with AKR-type BW5147.

Transplantation tolerance and autoimmunity after xenogeneic thymus transplantation.

Successful grafting of vascularized xenografts (Xgs) depends on the ability to reliably induce both T cell-independent and -dependent immune tolerance. After temporary NK cell depletion, B cell suppression, and pretransplant infusion of donor Ags, athymic rats simultaneously transplanted with hamster heart and thymus Xgs developed immunocompetent rat-derived T cells that tolerated the hamster Xgs but provoked multiple-organ autoimmunity. The autoimmune syndrome was probably due to an insufficient development of tolerance for some rat organs; for example, it led to thyroiditis in the recipient rat thyroid, but not in simultaneously transplanted donor hamster thyroid.

Induction of specific transplantation tolerance across xenogeneic barriers in the T-independent immune compartment.

After transplantation of primarily vascularized xenografts (Xgs), T-independent mechanisms may lead to Xg rejection before T-cell activation even takes place. The possibility of achieving T-independent xenotolerance was evaluated in nude rats that normally reject hamster cardiac Xgs within 4 days by non-T cell-mediated mechanisms. After donor antigen infusion, temporary NK-cell depletion and a 4-week administration of Leflunomide, hamster heart grafts survived even after withdrawal of immunosuppression.

Increased mortality and impaired clonal deletion after staphylococcal enterotoxin B injection in old mice: relation to cytokines and nitric oxide production.

In the present study peripheral T cell tolerance and the occurrence of shock were evaluated in young and old mice after injection of Staphylococcal enterotoxin B (SEB). In young mice SEB immunization leads to tolerance based on deletion and anergy of SEB-reactive V beta 8+ T cells. With aging, mice developed resistance to SEB-induced deletion of V beta 8+ T cells as well as a high sensitivity to toxic shock.

Effect of treatments with cyclosporin A and anti-interferon-gamma antibodies on the mechanisms of immune tolerance in staphylococcal enterotoxin B primed mice.

The authors were interested to investigate the effect of Cyclosporin A (CsA), known to block interleukin-2 (IL-2) production, or of anti-interferon-gamma antibodies (anti-IFN-gamma Abs) in a model of T cell tolerance induced by the injection of the superantigen Staphylococcal Enterotoxin B (SEB) in BALB/c mice. After SEB immunization, tolerance was mainly achieved through deletion and anergy of SEB-reactive V beta 8+ T cells. Association of CsA treatment with SEB led to a greater decrease of the percentage of V beta 8+ CD4+ lymphocytes in the spleen and an abolition of clonal energy.

Use of the methylxanthine derivative A802715 in transplantation immunology: I. Strong in vitro inhibitory effects on CD28-costimulated T cell activities.

Background: Recently, methylxanthines such as pentoxifylline (PTX) were shown to be immunosuppressive in vitro. Unfortunately, when used in transplant patients, PTX was poorly active as an immunosuppressant. Here we report that the new methylxanthine derivative A802715 not only is more active than PTX, it also suppresses the cyclosporine (CsA)-resistant "signal two"-dependent pathway of T cell proliferation, making it an interesting drug to associate with CsA.

The human immunodeficiency virus(HIV) inhibitor 9-(2-phosphonylmethoxyethyl)adenine (PMEA) is a strong inducer of differentiation of several tumor cell lines.

9-(2-phosphonylmethoxyethyl)adenine (PMEA) is the prototype compound of a series of acyclic nucleoside phosphonate derivatives endowed with potent and selective anti-retroviral activity in vitro and in vivo. We have now found that PMEA is also a potent inducer of differentiation of a number of tumor cells, including human erythroleukemia K562 cells, rat choriocarcinoma RCHO cells and human acute promyelocytic leukemic HL-60 cells. At 10 microM PMEA, rat RCHO cell cultures could be almost fully differentiated, and at 50 microM PMEA, approximately 50% of the K562 cells could be triggered to produce hemoglobin.

Influence of different growth factors on a rat choriocarcinoma cell line.

The influence of epidermal growth factor, insulin-like growth factors I and II, insulin, transforming growth factor beta 1 and transferrin on the growth of a postgestational rat choriocarcinoma was examined by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay. The cell line was cultured in RPMI 1640 medium supplemented with fetal calf serum, beta-mercaptoethanol, glucose, sodium pyruvate and antibiotics. The experiments were done in media supplemented with 10% (optimal) or 3% (suboptimal) fetal calf serum.

Establishment and characterization of a continuous in vitro line from a rat choriocarcinoma.

A continuous in vitro cell line of rat choriocarcinoma has been established. It is composed of pure trophoblast cells which multiply and differentiate. The morphology of the cells is very similar to normal rat cytotrophoblasts and giant cells.