Delay Rejection Research Articles

The Role of Direct Presentation by Donor Dendritic Cells in Rejection of Minor Histocompatibility Antigen-Mismatched Skin and Hematopoietic Cell Grafts

The success of transplantation is hampered by rejection of the graft by alloreactive T cells. Donor dendritic cells (DC) have been shown to be required for direct priming of immune responses to antigens from major histocompatibility complex-mismatched grafts. However, for immune responses to major histocompatibility complex-matched, minor histocompatibility (H) antigen mismatched grafts, the magnitude of the T-cell response to directly presented antigens is reduced, and the indirect pathway is more important. Therefore, we aimed to investigate the requirement for donor DC to directly present antigen from minor H antigen mismatched skin and hematopoietic grafts. Langerhans cell- or conventional (c)DC-depleted skin or hematopoietic cells from male DC-specific diphtheria toxin receptor mice were grafted onto, or injected into, syngeneic female recipients, and survival of the male tissue was compared with nondepleted tissue. Activation of the alloreactive immune response was tracked by the expansion of T cells specific for male HY-derived epitopes. Our data demonstrate that depletion of donor Langerhans cell, dermal cDC, or both from skin grafts prolongs their survival but does not prevent rejection. Extended survival correlates with delayed expansion of HY peptide-specific CD8 T cells. In addition, depletion of donor cDC delays rejection of male hematopoietic cells. Our results demonstrate for the first time that direct presentation of minor H antigens by donor DC is required for efficient rejection of skin and hematopoietic grafts by CD8 T cells. But, in the absence of donor DC, indirect presentation of minor antigens is sufficient to mediate the response.

Portal Venous Donor-Specific Transfusion in Conjunction with Sirolimus Prolongs Renal Allograft Survival in Nonhuman Primates

Pretransplant exposure to donor antigen is known to modulate recipient alloimmunity, and frequently results in sensitization. However, donor-specific transfusion (DST) can have a protolerant effect that is dependent on route, dose and coadministered immunosuppression. Rodent studies have shown in some strain combinations that portal venous (PV) DST alone can induce tolerance, and uncontrolled clinical use of PVDST has been reported. In order to determine if pretransplant PVDST has a clinically relevant salutary effect, we studied it and the influence of concomitant immunosuppression in rhesus monkeys undergoing renal allotransplantation. Animals received PVDST with unfractionated bone marrow and/or tacrolimus or sirolimus 1 week prior to transplantation. Graft survival was assessed without any posttransplant immunosuppression. PVDST alone or in combination with tacrolimus was ineffective. However, PVDST in combination with sirolimus significantly prolonged renal allograft survival to a mean of 24 days. Preoperative sirolimus alone had no effect, and peripheral DST with sirolimus prolonged graft survival in 2/4 animals, but resulted in accelerated rejection in 2/4 animals. These data demonstrate that PVDST in combination with sirolimus delays rejection in a modest but measurable way in a rigorous model. It may thus be a preferable method for donor antigen administration.

Getting rid of the cuckoo Cuculus canorus egg: why do hosts delay rejection?

Egg discrimination is well documented in many hosts of avian brood parasites, but the proximate mechanisms of egg recognition and rejection decisions are poorly understood. Relevant in this respect is the observation that rejectors of parasite eggs often delay their response. This delay has implications for understanding mechanisms important for egg recognition and is the main focus of the present study. We investigated experimentally the relative effects of egg mimicry and eggshell strength of common cuckoo Cuculus canorus eggs on the delay in rejection in marsh warblers Acrocephalus palustris. In addition, by video recording host responses, we elucidate the proximate mechanisms behind the delayed rejections. Host nests were experimentally parasitized with 3 types of real eggs differing in mimicry and/or eggshell strength. Both egg mimicry and eggshell strength significantly affected the time to rejection, but the effect of mimicry was dominant. The delayed rejection of mimetic eggs was explained by the existence of latency to the release of rejection behavior because of recognition problems. Second, when rejection response towards mimetic eggs was initiated, it was less intense compared with hosts experiencing nonmimetic eggs. Our results are consistent with the hypothesis that host motivation when confronted with mimetic eggs needs to increase above a certain threshold before rejection behavior is released, which likely minimizes the risk of recognition errors. An additional component of the delay in rejection as shown by hosts facing nonmimetic eggs was the seemingly inefficient host rejection behavior, probably reflecting lack of previous experience. Key words: brood parasitism, cuckoo, egg recognition, eggshell strength, marsh warbler, mimicry. [Behav Ecol]

Immunosuppression by the JAK3 Inhibitor CP-690,550 Delays Rejection and Significantly Prolongs Kidney Allograft Survival in Nonhuman Primates

Janus kinase 3 (JAK3) mediates signal transduction from cytokine receptors using the common chain (gammac). Because mutations in genes encoding gammac or JAK3 result in immunodeficiency, we investigated the potential of a rationally designed inhibitor of JAK3, CP-690,550, to prevent renal allograft rejection in nonhuman primates. Life-supporting kidney transplantations were performed between mixed leukocyte reaction-mismatched, ABO blood group-matched cynomolgus monkeys. Animals were treated with CP-690,550 (n = 18) or its vehicle (controls, n = 3) and were euthanized at day 90 or earlier if there was allograft rejection. Mean survival time (+/- standard error of mean) in animals treated with CP-690,550 (53 +/- 7 days) was significantly longer than in control animals (7 +/- 1 days, P=0.0003) and was positively correlated with exposure to the drug (r = 0.79, P < 0.01). Four treated animals were euthanized at 90 days with a normal renal function and low-grade rejection at final pathology. Occurrence of rejection was significantly delayed in treated animals (46 +/- 7 days from transplantation vs. 7 +/- 1 days in controls, P = 0.0003). Persistent anemia, polyoma virus-like nephritis (n = 2), and urinary calcium carbonate accretions (n = 3) were seen in animals with high exposure. Natural killer cell and CD4 and CD8 T-cell numbers were significantly reduced in treated animals. Blood glucose, serum lipid levels, and arterial blood pressure were within normal range in treated animals, and no cancers were demonstrated. CP-690,550 is the first reported JAK3 inhibitor combining efficacy and good tolerability in a preclinical model of allotransplantation in nonhuman primates and thus has interesting potential for immunosuppression in humans.

Genetic deletion of chemokine receptor CXCR3 or antibody blockade of its ligand IP-10 modulates posttransplantation graft-site lymphocytic infiltrates and prolongs functional graft survival in pancreatic islet allograft recipients

Background. Interaction of chemokine receptor CXCR3 with its ligand IP-10 mediates effector cell trafficking to sites of allograft rejection in murine models of whole organ allotransplantation. We hypothesized that blocking the CXCR3/IP-10 interaction would impair posttransplantation leukocyte trafficking to and delay rejection of pancreatic islet allografts. Methods. A/J strain murine islets were implanted to the kidney capsule of H-2 disparate, streptozotocin-induced diabetic wild type (WT), CXCR3 deficient (CXCR3−/−) or IP-10 antibody-treated WT (αIP-10) C57BL/6 recipients. Representative grafts from each group were harvested at day 7. Ribonuclease protection assay was used to determine gene expression for cell markers F4/80 (macrophages), CD8 (type I T cells), CD4 (type II T cells), and CD 19 (natural killer cells), and for chemokines IP-10, MIP-1α, MIP-1β, MCP-1, and RANTES. Immunohistochemistry was used to confirm ribonuclease protection assay infiltrate data. Graft-site chemokine gene expression and cellular infiltrate were correlated with time to functional graft rejection. Results. Untreated WT recipients demonstrated heavy graft-site cell infiltrates and increased graft-site gene expression for cell markers F4/80, CD8, CD4, and CD19, and for chemokines RANTES, IP-10, and MIP-1β at day 7. In comparison with untreated WT, αIP-10-treated WT and CXCR3−/− recipients demonstrated the same degree of chemokine gene expression but less lymphocytic infiltrate. The mean length of allograft survival was 12.7 ± 3.1 days in untreated WT versus 20.2 ± 2.7 days (P <.05) for CXCR3−/−- and 19.7 ± 2.3 days (P <.05) for αIP-10-treated WT recipients. Conclusions. CXCR3 gene deletion or αIP-10 antibody therapy modulates posttransplantation lymphocytic graft infiltration and statistically prolongs graft survival in murine islet allograft recipients. (Surgery 2003;134:126-33.)

Modulation of tissue-specific immune response to cardiac myosin can prolong survival of allogeneic heart transplants.

The role of immune response to tissue-specific Ags in transplant rejection is poorly defined. We have previously reported that transplantation of cardiac allografts triggers a CD4(+) Th1 cell response to cardiac myosin (CM), a major contractile protein of the heart, and that pretransplant activation of proinflammatory CM-specific T cells accelerates rejection. In this study, we show that administration of CM together with IFA (CM/IFA) can prevent acute rejection of an allogeneic heart transplant. Prolongation of cardiac graft survival is associated with activation of CM- and allo-specific T cells secreting type 2 cytokines (IL-4, IL-5) and reduction of the frequency of proinflammatory IFN-gamma-secreting (type 1) alloreactive T cells. Blocking of IL-4 cytokine with Abs abrogates the prolongation. CM/IFA treatment prevents acute rejection of MHC class I-mismatched, but not fully mismatched grafts. However, if donor heart is devoid of MHC class II expression, CM-IFA administration delays rejection of fully allogeneic cardiac transplants. This finding suggests that the effect of CM modulation depends on the type (direct vs indirect) and strength of recipient's CD4(+) T cell alloresponse. Our results underscore the important role of host immunity to tissue-specific Ags in the rejection of an allograft. This study demonstrates that modulation of the immune response to a tissue-specific Ag can significantly prolong cardiac allograft survival, an observation that may have important implications for the development of novel selective immune therapies in transplantation.

A High Isoflavone Soy Protein Diet and Intravenous Genistein Delay Rejection of Rat Cardiac Allografts

Genistein, a soy isoflavone, has in vitro immunosuppressive properties. We investigated whether genistein or dietary soy protein containing isoflavones could influence the outcome of rat cardiac allografts. Lewis rats were fed a diet with protein from high isoflavone soy protein fraction (HIS), casein (CAS) or casein with isoflavones added (CI) starting 1 wk before heart transplants from Wistar Furth donors, and continuing throughout the study. HIS-fed rats had significantly prolonged time to rejection compared with CAS- and CI-fed recipients (10.8 +/- 2.62 vs. 7.18 +/- 0.75 and 7.22 +/- 0.44 d, P < 0.001). Intravenous genistein [20mg/(kg. d) for 14 d] significantly prolonged heart survival compared with controls and dissolvent-treated recipients (23.2 +/- 7.4 vs. 8.4 +/- 1.3 and 11.4+/3.6 d, P < 0.0005), and had an additive effect when given to heart recipients also receiving low dose cyclosporine for 7 d (30.8 +/- 2.3 vs. 23.4 +/- 2.4 d, P < 0.005). Concanavalin A-stimulated lymphocytes, isolated from Lewis rats given intraperitoneal genistein for 7 d, had decreased production of interferon gamma compared with controls or dimethyl sulfoxide-treated groups (22.6 +/- 9.9 vs 149 +/- 105 and 154 +/- 103 micro g/L, P < 0.05). In conclusion, a high isoflavone soy diet and intravenous genistein, but not isoflavone extract alone, delay rejection of rat cardiac allografts, with an additive effect in cyclosporine-treated rats. In addition, intraperitoneal genistein has immunosuppressive properties in vivo.

Progesterone Inhibits Rejection of Xenogeneic Transplants in the Sheep Uterus

Objectives: One of the proposed roles of progesterone is to prevent maternal immunological destruction of the allogeneic conceptus. Here, it was demonstrated that progesterone allows survival of a xenotransplant placed in the uterine lumen. Methods: Ovariectomized ewes, surgically prepared to have ligatures around each uterine horn, were given daily subcutaneous injections of 50 mg progesterone or vehicle (sesame oil). After 30 days of treatment, mouse hybridoma cells were transplanted to one ligated uterine horn and phosphate-buffered saline was injected into the other horn. The uterus was flushed after an additional 14 days of treatment and hybridoma cells were identified by immunofluorescence. Results: Overall, hybridoma cells were recovered from 4 of 5 progesterone-treated ewes and 1 of 5 vehicle-treated ewes. Immunohistochemical analysis of intercaruncular endometrium using antibodies towards CD8, γδ, and CD45R lymphocyte markers revealed that local presence of hybridoma cells caused a significant increase in CD8+ cells in all tissue compartments. While not significant, the numbers of CD8+ cells in the luminal and glandular epithelium were lower for progesterone-treated ewes. Progesterone tended to increase γδ T cell numbers in the glandular epithelium. Conclusions: Results demonstrate that xenograft rejection in the uterus is associated with an increase in CD8+ cells in the endometrium and that progesterone can inhibit uterine tissue graft rejection responses sufficiently to allow survival or delay rejection of xenograft tissue.

Site-Specific Immunosuppression using a New Formulation of Topical Cyclosporine A with Polyethylene Glycol-8 Glyceryl Caprylate/Caprate

Purpose.Dermal application of immunosuppressants can be an effective means of achieving site-specific immunosuppression (SITE) on skin allografts in burn wound management and in the treatment of various immune skin disorders. We have previously reported success with topical cyclosporine A (tCsA) in the treatment of skin allograft rejection in rats. Using a new tCsA formulation with a penetration enhancer (PE), polyethylene glycol-8 (PEG-8) glyceryl caprylate/caprate (Labrasol, Gattefossé, St. Priest, France), in a trinary drug delivery system, we hypothesized that we would induce SITE and significantly delay rejection of dual skin allografts in rats.Methods.Dual rat skin allografts from Lewis × Brown–Norway (LBN) donors were grafted to Lewis (Lew) recipients. Experimental animals (EXP,n= 7) received a 10-day course of systemic cyclosporine (sCsA, 8 mg/kg/day) followed by topical application. One of the two allografts on each experimental animal received tCsA/PE application (5 mg/kg/day) until sacrifice (tCsA/PE-treated). The other allograft received vehicle only (vehicle-treated). Allogeneic controls (ALLO-CON,n= 9) received no sCsA or tCsA. First signs of rejection were determined based on the initial observation of erythema, hair loss, flakiness, and/or scabs.Results.The mean time to rejection for ALLO-CON allografts was 6.3 ± 0.7 days (ttest,P= 0.0013); for vehicle-treated allografts, 12.3 ± 3.8 days (pairedttest,P= 0.0146); and for tCsA/PE-treated allografts, 25.6 ± 5.4 days. The disparity of days to rejection between dual allografts in the ALLO-CON group was 0.0 ± 0.0 day and that between the tCsA/PE- and vehicle-treated dual allografts was 13.3 ± 3.9 days (ttest,P= 0.0016).Conclusions.A new formulation of tCsA in a trinary drug delivery system is successful at delaying the onset of rejection in dual skin allografts in rats by SITE, and PEG-8 glyceryl caprylate/caprate may represent a potentially effective transdermal penetration enhancer.

Intravenous Immunoglobulins for Therapeutic Use Contain Anti-idiotypes against Xenophile Antibodies and Prolong Discordant Graft Survival

Xenotransplantation between discordant species leads to a graft survival of a few minutes, due to binding of natural antibodies to the xenogeneic endothelial cells, complement activation, and endothelial cell activation. Polyclonal human immunoglobulins for intravenous use (IVIg) from normal donors have been proven effective in a variety of antibody-mediated disorders and contain anti-idiotypic antibodies directed against a number of disease-associated and natural antibodies. We have shown that administration of IVIg delays rejection of a guinea pig heart to a rat. We demonstrate herein that IVIg can inhibit the binding of xenoreactive rat IgG antibodies to guinea pig endothelial cells. This inhibition is likely due to the presence, among IVIg, of anti-idiotypic antibodies as F(ab′) 2fragments of IVIg were as effective as whole IVIg. In addition, natural anti-endothelium rat antibodies were retained on a column of F(ab′) 2fragments of IVIg coupled to Sepharose. The degree of inhibition of binding of IgG natural antibodies correlated with the survival of the xenograft when IVIg was administered prior to transplantation. Thus IVIg prolong xenograft survival through idiotypic–anti-idiotypic interactions with natural xenoreactive antibodies of the IgG isotype.

Delayed xenograft rejection of pig-to-baboon cardiac transplants after cobra venom factor therapy.

This study sought to (i) investigate the efficacy of cobra venom factor (CVF) in preventing hyperacute rejection (HAR) after pig-to-baboon heart transplantation, (ii) examine the effect of additional splenectomy (Spx) and pharmacologic immunosuppression (IS), and (iii) study delayed graft rejection when HAR is avoided by complement depletion. Eleven recipient baboons received heterotopic pig heart transplants. Three received either no therapy or IS (cyclosporine + methylprednisolone +/- cyclophosphamide +/- methotrexate) at clinically well-tolerated doses, with graft survival for only 40, 32, and 15 min, respectively. Two received CVF+/-Spx, which extended survival to 5 and 6 days, respectively. Six underwent Spx + CVF therapy + IS; graft survival was 3 hr (technical complication), 6 days (death from sepsis), 10, 12, and 22 days (vascular rejection), and <25 days (euthanized for viral pneumonia with a functioning graft that showed histopathologic features of vascular rejection). Dense deposition of IgM and, to a lesser extent, IgG and IgA were seen on the endothelial cells within 1 hr of transplantation, but only trace levels of complement deposition were present in CVF-treated recipients. Within approximately 5-12 days, cardiac xenografts showed progressive infiltration by mononuclear cells, consisting primarily of activated macrophages producing tumor necrosis factor-alpha and small numbers of natural killer cells; T and B cells were absent. We conclude that (i) CVF prevents HAR, (ii) the addition of Spx + IS delays rejection, but (iii) the early deposition of antibody leads to progressive graft injury, resulting in (iv) delayed vascular rejection. Our findings indicate that the features of delayed xenograft rejection described in small animal models also occur in the pig-to-baboon model, and that rejection may occur in a complement-independent manner from the effects of antibody and/or host macrophages.

Evidence that rapamycin rescue therapy delays rejection of major (MHC) plus minor (non-MHC) histoincompatible heart allografts in rats.

The capacity of delayed onset of rapamycin (RAPA) therapy to block process of destruction was examined in rats undergoing heart allograft rejection. Untreated Wistar Furth (WFu; RT-1u) recipients reject Buffalo (BUF; RT-1b) heart allograft with a mean survival time (MST) of 6.5 +/- 0.5 days. A 14-day i.v.infusion of 0.8 mg/kg RAPA begun on the day of transplantation prolonged the survival to 74.1 +/- 20.2 days (P < 0.001), 0.2 mg/kg to 32.2 +/- 10.0 days (P < 0.001), and 0.08 mg/kg to 36.4 +/- 11.8 days (P < 0.001). When RAPA therapy (0.8 mg/kg) was begun 3 or 4 days after transplantation, the grafts survived 85.2 +/- 31.1 (P < 0.001), and 70.2 +/- 43.3 (P < 0.005) days, respectively. Therapy initiated on day 5 was much less effective; most transplants were rejected within 10 days; one graft survived 32 and two grafts 60 days (MST = 17.6 +/- 20.0, NS). A 0.2 mg/kg RAPA dose prolonged graft survival with initial use on days 3 (31.6 +/- 12.2 days; P < 0.001) or 4 (31.4 +/- 8.1 days; P < 0.001) but not on day 5. The 0.08 mg/kg RAPA prolonged hearts only when started on day 3 (47.2 +/- 2.7 days; P < 0.001) but not on days 4 or 5. WFu recipients treated with a subtherapeutic dose of cyclosporine (1 mg/kg; 9.1 +/- 1.5 days) displayed prolonged heart allograft function when treated subsequently with RAPA (0.8 or 0.08) beginning from days 4, 5, or 6 postgrafting. These in vivo results are supported by in vitro experiments. The frequency of BUF alloreactive elements among normal WFu LN cells (fTc) was 337 +/- 139/10(6) T cells in limiting dilution assay. Addition of RAPA (1 muMol) at the beginning of culture significantly reduced (P < 0.025) the fTc to 17 +/- 6.6/10(6), or alternatively on days 4 or 6 to 37.3 +/- 20.0/10(6) and 58.6 +/- 21.8/10(6), respectively. Thus, both in vivo and in vitro data demonstrate that delayed RAPA therapy may interrupt alloimmune reactions.

A technique for transplanting pancreatic islets as a vascularized graft and prevention of rejection with cyclosporin A.

Transplants of isolated allogeneic pancreatic islets behave as if extremely immunogenic but vascularized segmental pancreatic allografts do not evoke such a rapid rejection of islet tissue. We have transplanted rat pancreatic islets as a vascularized graft by implanting isolated islets under the renal capsule of a syngeneic diabetic rat and, after successful reversal of diabetes, a composite graft of kidney and islets was transplanted into an allogeneic diabetic host. Cyclosporin A was used to suppress rejection of the allografts in doses that have previously been shown to completely suppress rejection of renal allografts and delay rejection of vascularized segmental pancreatic allografts. This strategy produced indefinite survival of the allogeneic isolated pancreatic islets.

SKIN GRAFTS: DELAYED REJECTION BETWEEN PAIRS OF CATTLE TWINS SHOWING ERYTHROCYTE CHIMERISM.

Although dizygotic cattle twins with erythrocyte chimerism exhibit complete tolerance to each other's hematopoietic tissues exchanged in utero by way of chorionic anastomoses, they may not be completely tolerant to each other's histocompatibility antigens. Skin grafts exchanged between partners of 21 pairs of chimeric twins were rejected by more than half of the twins in an average of 250 days.