Donor-specific Blood Transfusion Research Articles

(676) - Donor-Specific Blood Transfusion is Feasible and Safe in Mice: A Proof-of-Concept Study

(676) - Donor-Specific Blood Transfusion is Feasible and Safe in Mice: A Proof-of-Concept Study

Effect of donor-specific blood transfusions on allotransplanted teeth in a monkey model: Histoquantification of periodontal healing.

Pre-transplant blood transfusions have previously shown a positive effect on organ allograft survival in humans and various animal species. The aims of this study were, first, to evaluate the effect of pre-transplant donor-specific blood transfusions on periodontal healing of fully developed allotransplanted teeth in monkeys; and second, to investigate the immune response against donor antigens and to determine a possible correlation between alloimmune reactions and histopathological signs of rejection. Twenty monkeys (Cercopithecus aethiops) were divided into ten pairs with similar sizes of incisors. One monkey in each pair gave three transfusions to the other monkey with 1-week intervals. One week after the last transfusion, each pair exchanged simultaneously a central maxillary incisor and a lateral mandibular incisor. The corresponding central maxillary and mandibular lateral incisors were autotransplanted to the contralateral sockets. All teeth were treated endodontically per-operatively. Histocompatibility was evaluated by mixed lymphocyte culture before the first transfusion, while alloantibodies and cell-mediated alloresponses were measured before transfusions and at 2 and 8weeks after transplantation. All animals were sacrificed 8weeks after tooth transplantation. Serial sections of the transplanted teeth were quantified histologically. Mixed lymphocyte cultures showed positive reactions in 19 of 20 cases, indicating incompatibility. The majority of the monkeys developed antibodies towards the tooth donor. Cell-mediated cytotoxicity was negative in all monkeys. Histoquantification revealed a mean score of 70% normal periodontal ligament (PDL) in autotransplanted teeth, with 5% ankylosis. The allografts had a mean score of 17% normal PDL and 63% ankylosis, with no significant influence of transfusion. However, in the mandibular grafts, a tendency towards a positive transfusion effect was seen. Donor-specific blood transfusion did not reduce ankylosis in tooth allografts. The healing of mandibular incisor tooth allografts was improved, but not that of maxillary incisors. Donor-specific antibodies showed no effect on the survival of allograft PDL.

Novel Targeting to XCR1+ Dendritic Cells Using Allogeneic T Cells for Polytopical Antibody Responses in the Lymph Nodes.

Vaccination strategy that induce efficient antibody responses polytopically in most lymph nodes (LNs) against infections has not been established yet. Because donor-specific blood transfusion induces anti-donor class I MHC antibody production in splenectomized rats, we examined the mechanism and significance of this response. Among the donor blood components, T cells were the most efficient immunogens, inducing recipient T cell and B cell proliferative responses not only in the spleen, but also in the peripheral and gut LNs. Donor T cells soon migrated to the splenic T cell area and the LNs, with a temporary significant increase in recipient NK cells. XCR1+ resident dendritic cells (DCs), but not XCR1− DCs, selectively phagocytosed donor class I MHC+ fragments after 1 day. After 1.5 days, both DC subsets formed clusters with recipient CD4+ T cells, which proliferated within these clusters. Inhibition of donor T cell migration or depletion of NK cells by pretreatment with pertussis toxin or anti-asialoGM1 antibody, respectively, significantly suppressed DC phagocytosis and subsequent immune responses. Three allogeneic strains with different NK activities had the same response but with different intensity. Donor T cell proliferation was not required, indicating that the graft vs. host reaction is dispensable. Intravenous transfer of antigen-labeled and mitotic inhibitor-treated allogeneic, but not syngeneic, T cells induced a polytopical antibody response to labeled antigens in the LNs of splenectomized rats. These results demonstrate a novel mechanism of alloresponses polytopically in the secondary lymphoid organs (SLOs) induced by allogeneic T cells. Donor T cells behave as self-migratory antigen ferries to be delivered to resident XCR1+ DCs with negligible commitment of migratory DCs. Allogeneic T cells may be clinically applicable as vaccine vectors for polytopical prophylactic antibody production even in asplenic or hyposplenic individuals.

Oscar Salvatierra: helped draft the US National Organ Transplant Act of 1984 and fought for its passage

Lucile Packard Foundation for Children’s Health Oscar Salvatierra Jr was widely acknowledged as an outstanding paediatric kidney transplantation surgeon. He approached each patient with one goal in mind: to make...

Single blood transfusion induces the production of donor-specific alloantibodies and regulatory T cells mainly in the spleen.

Donor-specific blood transfusion is known to induce alloresponses and lead to immunosuppression. We examined their underlying mechanisms by employing fully allogeneic rat combinations. Transfused recipients efficiently produced alloantibodies of the IgM and IgG subclasses directed against donor class I MHC. The recipients exhibited active expansion of CD4+ T cells and CD4+FOXP3+ regulatory T cells (Treg cells), followed by CD45R+ B cells and IgM+ or IgG subclass+ antibody-forming cells mainly in the spleen. From 1.5 days, the resident MHCII+CD103+ dendritic cells (DCs) in the splenic T-cell area, periarterial lymphocyte sheath, formed clusters with recipient BrdU+ or 5-ethynyl-2'-deoxyuridine+ cells, from which the proliferative response of CD4+ T cells originated peaking at 3-4 days. Transfusion-induced antibodies had donor passenger cell-depleting activity in vitro and in vivo and could suppress acute GvH disease caused by donor T cells. Furthermore, Treg cells significantly suppressed mixed leukocyte reactions in a donor-specific manner. In conclusion, single blood transfusion efficiently induced a helper T-cell-dependent anti-donor class I MHC antibody-forming cell response with immunoglobulin class switching, and a donor-specific Treg cell response mainly in the spleen, probably by way of the indirect allorecognition via resident DCs. These antibodies and Treg cells may be involved, at least partly, in the donor-specific transfusion-induced suppression of allograft rejection.

A Novel Model on DST-Induced Transplantation Tolerance by the Transfer of Self-Specific Donor tTregs to a Haplotype-Matched Organ Recipient

Donor-specific blood transfusion (DST) can lead to significant prolongation of allograft survival in experimental animal models and sometimes human recipients of solid organs. The mechanisms responsible for the beneficial effect on graft survival have been a topic of research and debate for decades and are not yet fully elucidated. Once we discover how the details of the mechanisms involved are linked, we could be within reach of a procedure making it possible to establish donor-specific tolerance with minimal or no immunosuppressive medication. Today, it is well established that CD4+Foxp3+ regulatory T cells (Tregs) are indispensable for maintaining immunological self-tolerance. A large number of animal studies have also shown that Tregs are essential for establishing and maintaining transplantation tolerance. In this paper, we present a hypothesis of one H2-haplotype-matched DST-induced transplantation tolerance (in mice). The formulated hypothesis is based on a re-interpretation of data from an immunogenetic experiment published by Niimi and colleagues in 2000. It is of importance that the naïve recipient mice in this study were never immunosuppressed and were therefore fully immune competent during the course of tolerance induction. Based on the immunological status of the recipients, we suggest that one H2-haplotype-matched self-specific Tregs derived from the transfusion blood can be activated and multiply in the host by binding to antigen-presenting cells presenting allopeptides in their major histocompatibility complex (MHC) class II (MHC-II). We also suggest that the endothelial and epithelial cells within the solid organ allograft upregulate the expression of MHC-II and attract the expanded Treg population to suppress inflammation within the graft. We further suggest that this biological process, here termed MHC-II recruitment, is a vital survival mechanism for organs (or the organism in general) when attacked by an immune system.

Immunomodulation by Mesenchymal Stem Cells: Lessons From Vascularized Composite Allotransplantation.

Mesenchymal stem cells (MSC) are under investigation as a novel means of immunomodulation in solid organ transplantation1 and encouraging data from early clinical trials have been reported.2,3 Recently, it was demonstrated that the beneficial immunomodulatory effects of MSC are not limited to the transplantation of solid organs, but are also applicable to vascularized composite allotransplantation (VCA).4 In their elegant article, Plock et al5 explored the mechanisms of MSC therapy in VCA, especially concerning timing and frequency of MSC administrations. The timing of MSC administration appears to be crucial for the therapeutic effect on composite allograft survival, and repeated administrations were shown to improve therapeutic efficacy. There are a number of aspects to keep in mind in this study that can help us understand the mechanisms of action of MSC therapy in more detail. The first is that donor MSC were used, which means that the possibility that the observed prolongation of graft survival depends on donor-specific desensitization cannot be ruled out. This would still be an interesting finding and may indicate that donor MSC administration could be used as a more controlled alternative to donor-specific blood transfusions, which have earlier been under investigation for inducing T cell nonresponsiveness in organ recipients.6 MSC can be precisely dosed, and furthermore, levels of HLA molecules, which are at the basis of T cell nonresponsiveness induced by donor cell infusion, can be controlled by treatment of MSC with cytokines, such as IFNγ and TNFα. The present study may suggest that the induction of T cell nonresponsiveness by presentation of donor HLA by MSC may deserve further investigation. Second, Plock et al treated their recipient animals with rabbit-antirat lymphocyte polyclonal serum (ALS) 4 days before and 1 day after surgery. MSC were thus administered in a partially lymphocyte depleted environment. This may have played a role in the therapeutic effect of theMSC administrations, and it may explain some of the differences found between administration of MSC on postoperative day 1 compared with MSC administered on day 4. On day 1, MSC encountered a sharply reduced lymphocyte population with dying lymphocytes, whereas at postoperative day 4, MSC encountered a carefully recovering lymphocyte population. The different conditions concerning the lymphocyte compartment may be accompanied with differences in cytokine profiles, which act upon the administered MSC. Therefore, in addition to timing of MSC administration in relation to the transplantation, timing of MSC in relation to the ALS treatment may also play a role in the observed therapeutic effects of the MSC administrations. This is useful knowledge to take into consideration for further studies. Third, the observed peripheral blood cell chimerism in the transplanted animals is intriguing. Chimerism is considered to be associated with prolongation of graft survival, and the data of the present study support this. Because MSC do not circulate in the blood7,8 and intravenously infused MSC disappear swiftly after administration, the circulating donor cells have to represent leukocytes derived from the vascularized composite transplant. The data show that coadministration of MSC at least temporarily increases the presence of donor cells in the circulation. This would suggest that MSC therapy enhances the survival of circulating donor derived leukocytes, thereby supporting chimerism. If this is the case, it could represent another mechanism of prolongation of graft survival by MSC. The question is whether the support of chimerism by MSC is specific for VCA or whether this applies for other transplants as well. Overall, the study by Plock et al adds to the accumulating evidence that in accordance to their effects in graftversus- host disease and solid-organ transplantation MSC have a therapeutic future in VCA. The experimental details contribute to better understanding of MSC treatment and to the development of effective therapy.

Immunomodulatory Effect of Nuclear Factor-κB Inhibition by Dehydroxymethylepoxyquinomicin in Combination With Donor-Specific Blood Transfusion

Nuclear factor-κB (NF-κB) is a key molecule in alloimmune responses, however, its role in tolerance induction is not clear. We have previously reported that dehydroxymethylepoxyquinomycin (DHMEQ), a novel NF-κB inhibitor, prolongs cardiac allograft survival. In this study, we evaluated the immunomodulatory effects of DHMEQ when combined with a donor-specific blood transfusion (DST), and assessed whether the treatment induces tolerance in a mouse heart transplantation model. DST (20×10 splenocytes) was given intravenously at day -7. DHMEQ (30 mg/kg/day) was administered intraperitoneally for 14 days after DST. Graft survival and histology were evaluated. The underlying mechanisms of immunomodulation by DST and DHMEQ treatments were investigated by assessing alloimmune responses after transplantation. In fully mismatched H2-to-H2 heart transplants, DST alone prolonged allograft median survival time to 15 days, whereas when DST was combined with DHMEQ treatment, the graft median survival time was prolonged to 39.5 days. When the donor-recipient strain combination was reversed, that is, H2-to-H2, heart transplants were accepted (>150 days survival) in more than 60% of recipients treated with a DST and DHMEQ, whereas control allografts were all rejected within 8 days. The combined therapy markedly inhibited immune responses by both the direct and indirect allorecognition pathways mainly attributed to promotion of activation-induced cell death and Treg generation. Our results demonstrate the distinctive ability of NF-κB inhibition in combination with donor alloantigen to promote transplantation tolerance through multiple cellular mechanisms.

Characterization of waves of leukocyte recruitment to the lung allograft and the effect of CTLA4-Ig

MHC-mismatched lung allografts are rapidly rejected by the host immune response. We analyzed cells infiltrating the grafted lung tissue using a collagenase-digestion method. The grafted lung was filled with host-derived leukocytes as early as day 1 post transplantation and the majority of the initial infiltrating cells were granulocytes. This initial influx of granulocytes waned rapidly, followed by a steady increase in lymphocytes, particularly T cells, and then by macrophages. The proportion of CD4 + T cells that express CD25 were increased in the graft the majority of which were activated CD4 + cells. We applied cytotoxic T-lymphocyte-associated antigen 4 (CTLA4)-Ig treatment in combination with donor-specific blood transfusion to the transplantation of lung allograft, which was significantly prolonged by the treatment. To examine the cellular and molecular basis of the inhibition of the graft rejection, we evaluated number and cytokine mRNA expression of the cells infiltrating in the lung allograft using collagenase-digestion method, although we were unable to detect significant effects of the treatment. Taken together, this study demonstrates that single cell suspensions from cellular infiltrates of lung tissue is useful for phenotypical and functional studies on cells infiltrating lung tissue after graft transplantation. ACTA MEDICA NAGASAKIENSIA 56: 27-34, 2011

Induction of Foxp3-Expressing Regulatory T-Cells by Donor Blood Transfusion Is Required for Tolerance to Rat Liver Allografts

BackgroundDonor-specific blood transfusion (DST) prior to solid organ transplantation has been shown to induce long-term allograft survival in the absence of immunosuppressive therapy. Although the mechanisms underlying DST-induced allograft tolerance are not well defined, there is evidence to suggest DST induces one or more populations of antigen-specific regulatory cells that suppress allograft rejection. However, neither the identity nor the regulatory properties of these tolerogenic lymphocytes have been reported. Therefore, the objective of this study was to define the kinetics, phenotype and suppressive function of the regulatory cells induced by DST alone or in combination with liver allograft transplantation (LTx).Methodology/Principal FindingsTolerance to Dark Agouti (DA; RT1a) rat liver allografts was induced by injection (iv) of 1 ml of heparinized DA blood to naïve Lewis (LEW; RT1l) rats once per week for 4 weeks prior to LTx. We found that preoperative DST alone generates CD4+ T-cells that when transferred into naïve LEW recipients are capable of suppressing DA liver allograft rejection and promoting long-term survival of the graft and recipient. However, these DST-generated T-cells did not express the regulatory T-cell (Treg) transcription factor Foxp3 nor did they suppress alloantigen (DA)-induced activation of LEW T-cells in vitro suggesting that these lymphocytes are not fully functional regulatory Tregs. We did observe that DST+LTx (but not DST alone) induced the time-dependent formation of CD4+Foxp3+ Tregs that potently suppressed alloantigen-induced activation of naïve LEW T-cells in vitro and liver allograft rejection in vivo. Finally, we present data demonstrating that virtually all of the Foxp3-expressing Tregs reside within the CD4+CD45RC− population whereas in which approximately 50% of these Tregs express CD25.Conclusions/SignificanceWe conclude that preoperative DST, in the absence of liver allograft transplantation, induces the formation of CD4+ T-cells that are not themselves Tregs but give rise directly or indirectly to fully functional CD4+CD45RC−Foxp3+Tregs when transferred into MHC mismatched recipients prior to LTx. These Tregs possess potent suppressive activity and are capable of suppressing acute liver allograft rejection. Understanding the mechanisms by which preoperative DST induces the generation of tolerogenic Tregs in the presence of alloantigens may lead to the development of novel antigen-specific immunological therapies for the treatment of solid organ rejection.

Intestinal Ischemia Reperfusion and Lipopolysaccharide Transform a Tolerogenic Signal into a Sensitizing Signal and Trigger Rejection

After intestinal transplantation (ITx), rejection is vigorous and tolerance is difficult to achieve. A possible reason for this phenomenon is that ITx and ischemia reperfusion injury are accompanied by translocation of lipopolysaccharide (LPS), a "danger" signal capable of activating adaptive alloimmunity against Tx antigens. To study that, we used our previously described rat model where donor-specific blood transfusion (DSBT) induces tolerance to fully mismatched heart allografts. In this model, control grafts are rejected within 9 days, whereas 100% of DSBT pretreated grafts survive long term. In contrast with heart Tx, an identical DSBT protocol failed to induce tolerance in 57% of recipients after ITx (P<0.05). We hypothesized that DSBT promotes tolerance to heart but not intestinal allografts (partly) because of ischemia/reperfusion injury and LPS translocation associated with ITx. We tested this hypothesis by adding to DSBT an inflammatory signal in the form of a remote intestinal/ischemia reperfusion injury or by administrating 0.1 mg of LPS. These maneuvers (partially) abrogated tolerance induction (P<0.05). Addition of a danger signal (remote intestinal ischemia/reperfusion) transforms a tolerogenic signal (DSBT) into a sensitizing signal and may lead to graft rejection. This effect is mediated in part by LPS. This may, partly, account for the high rejection rate and the difficulty to induce graft acceptance after ITx.

Pre-kidney-transplant blood transfusions do not improve transplantation outcome: a Dutch national study

Female renal transplant candidates are prone to be sensitized by prior pregnancies, and undetected historical sensitization might decrease transplantation outcome. Hypothesis of our study was that pre-transplant blood transfusions (PTFs) can elucidate historical sensitization and that the avoidance of the associated antigens can improve transplantation outcome. Data from all female non-immunized renal transplant candidates who received a random PTF (rPTF) (n = 620), matched PTF (mPTF) (one HLA-A and B and one HLA-DR match) (n = 86) or donor-specific blood transfusion (DST) (n = 100) between 1996 and 2006 were collected. Complement-dependent cytoxicity was used to detect anti-HLA antibodies. Sensitization and transplantation outcomes after a PTF were analyzed. Non-immunized female renal transplant recipients who did not receive a PTF were used as the control group. In 165 patients, anti-HLA antibodies (IgG) were detected after the PTF. Both historical and primary sensitizations were found. A DST induced donor-specific anti-HLA antibodies in 25% of the DST recipients. Our policy did not improve transplantation outcome in recipients of a kidney from a deceased donor (n = 368) or in recipients of a living donor [DST (n = 49) and mPTF (n = 66)]. A PTF did elucidate historical sensitization but induce primary sensitization as well. No beneficial effect of PTFs on transplantation outcome was found, and PTFs with the intention to detect historical sensitization are therefore not suggested.

Induction of Regulatory T-cells by Donor-Specific Blood Transfusion in the Absence or Presence of Liver Allograft Transplantation (141.43)

Abstract Donor-specific blood transfusion (DST) has been shown to be effective at inducing tolerance and long-term survival in animals transplanted with MHC-mismatched tissue. The objective of this study was to ascertain how DST alone or in combination with liver allograft transplantation (LTx) affects the generation and function of regulatory T-cells in vitro and in vivo. We found that DST alone generates CD4+ T-cells that when transferred into naïve recipients suppress liver allograft rejection despite expressing little or no Foxp3 at the time of adoptive transfer. In addition, we present the novel finding that DST plus LTx (but not DST alone) increases the formation of Foxp3-expressing regulatory T-cells (Tregs) that suppress alloantigen-induced activation in vitro as well as induce long term tolerance to liver allografts when adoptively transferred into naïve recipients prior to LTx. Finally we demonstrate that virtually all Foxp3-expressing Tregs reside within the CD4+CD45RC- population whereas these Tregs are equally distributed between the CD4+CD25+ and CD4+CD25- populations. Taken together, our data suggest that DST administration, in the absence of allograft transplantation, induces the formation of CD4+ T-cells that are not Tregs themselves but develop into fully functional Foxp3+ Tregs or help to induce the formation of Foxp3+ Tregs following allograft transplantation.

An Immunomodulatory Role for Follistatin‐Like 1 in Heart Allograft Transplantation

Donor-specific tolerance to heart allografts in the rat can be achieved by donor-specific blood transfusions (DST) before transplantation. We have previously reported that this tolerance is associated with strong leukocyte infiltration, and that host CD8(+) T cells and TGFbeta are required. In order to identify new molecules involved in the induction phase of tolerance, we compared tolerated and rejected heart allografts (suppressive subtractive hybridization) 5 days after transplantation. We identified overexpression of Follistatin-like 1 (FSTL1) transcript in tolerated allografts compared to rejected allografts or syngeneic grafts. We show that FSTL1 is overexpressed during both the induction and maintenance phase of tolerance, and appears to be specific to the tolerance model induced by DST. Analysis of graft-infiltrating cells revealed predominant expression of FSTL1 in CD8(+) T cells from tolerated grafts, and depletion of these cells prior to transplantation abrogated FSTL1 expression and heart allograft survival. Moreover, overexpression of FSTL1 by adenovirus gene transfer in vivo significantly prolonged allograft survival in association with inhibition of the proinflammatory cytokines, IL6, IL17 A and IFNgamma. Taken together, these results suggest that FSTL1 could be an active component of the mechanisms mediating heart allograft tolerance.

The Protective Effect of CD8 +CD28 − T Suppressor Cells On The Acute Rejection Responses in Rat Liver Transplantation

Regulatory T cells (Tr) or T-suppressor cells (Ts), which include CD4 +CD25 + T cells and CD8 +CD28 − T cells respectively, have been shown to be essential for the induction and maintenance of immune tolerance. We have investigated the effect of CD8 +CD28 − Ts and CD4 +CD25 + Tr on acute rejection responses in rat liver transplantation (OLT). Methods CD8 +CD28 − Ts/CD4 +CD25 + Tr were obtained from inbred and naïve rats that show spontaneous tolerance to OLT. Adoptive transfers were performed in acute rejection models of various strain combinations with survival times observed to evaluate suppressive effects. Donor-specific blood transfusion (DST) was used to induce CD8 +CD28 − Ts in naïve rats, which were assayed in vitro using carboxyfluorescein diacetate succinimidyl easter-labeled one-way mixed lymphocyte reactions. Secondary adoptive transfers of DST-induced CD8 +CD28 − Ts were also performed in an acute OLT rejection model. Results CD8 +CD28 − Ts from tolerant OLT model rats possessed immunosuppressive activity in allogeneic recipients; adoptive transfers of these cells alleviated the acute rejection responses. However, CD4 +CD25 + Tr derived from tolerant or naïve rats failed to do so. In vitro DST-induced CD8 +CD28 − Ts inhibited alloantigen T-cell responses in naïve syngeneic rats in an antigen-specific manner. Secondary adoptive transfer of DST-induced CD8 +CD28 −Ts further reduced acute rejection but not chronic rejection responses. Conclusions CD8 +CD28 − Ts cells protected allogeneic recipients from acute rejection in rat OLT. Furthermore, this activity was not present in CD4 +CD25 +Tr. DST was observed to be an effective method to generate functional CD8 +CD28 −Ts in naïve rats.

CD154 Blockade, Sirolimus, and Donor-Specific Transfusion Prevents Renal Allograft Rejection in Cynomolgus Monkeys Despite Homeostatic T-Cell Activation

CD154-specific antibodies have been shown to prevent acute rejection in many preclinical models including nonhuman primates (NHPs). However, they have been ineffective in pilot clinical trials, suggesting a need for more robust preclinical analysis. One factor affecting the disparate results may be related to the recipient's immune activation state. Specifically, adult humans have a high percentage of memory-phenotype T cells compared to young animals. Postdepletional homeostatic repopulation has been shown to enrich for memory-phenotype T cells and interfere with CD154-based therapies in rodents. We developed a NHP model nonspecifically enriched for peripheral memory-phenotype T cells. Thymectomized cynomolgus macaques underwent depletion with polyclonal anti-thymocyte globulin followed by repopulation. Peripheral phenotype was serially determined using polychromatic flow cytometry. In vitro response to donor and environmental antigens was also confirmed before and after manipulation. We then tested a regimen previously successful in rhesus monkeys combining anti-CD154, sirolimus, and donor-specific blood transfusion (DST), in a second primate species with and without the provocation of increased peripheral homeostatic T-cell activation. Monkeys that were thymectomized (n=3) and depleted recovered via homeostatic repopulation with a repertoire enriched for cells with a memory surface phenotype compared to unmanipulated controls (n=3). Despite a repertoire markedly enriched for memory-phenotype cells, the regimen effectively prevented acute rejection for the duration of therapy. Cynomolgus monkeys can be rendered memory phenotype enriched using homeostatic repopulation. Despite a generally activated T-cell repertoire, anti-CD154, sirolimus, and DST effectively prevents rejection in cynomolgus monkeys.

Functional Compartmentalization Following Induction of Long-Term Graft Survival with Pregraft Donor-Specific Transfusion

Long-term survival is achieved in rat recipients by pre-graft donor-specific blood transfusion. We characterized the immune compartments in long-term survivors and analyzed them for capacity to transfer tolerance and protect against chronic rejection. Splenocytes and spleen T cells from treated recipients transferred long-term graft survival to 100% of secondary recipients. In contrast, blood transferred graft survival to only 50% of recipients whereas blood T cells had no effect. An unaltered TCR repertoire, an increase in suppressive CD4+CD25+ T cells, a decrease in antidonor T-cell proliferative response and normal perforin-granzyme levels were the hallmarks of the spleen T cells. Blood T cells were characterized by a strongly altered CD8+ repertoire, normal CD4+CD25+ T cell number with unchanged antidonor T-cell proliferative response, an activated T-cell phenotype and an increase in perforin-granzyme levels. However, following the transfer of blood or spleen cells into secondary recipients, all grafts displayed chronic rejection. These findings provide evidence that distinct compartments play critical roles in DST recipients. Regulatory cells do not accumulate in blood, which appears to be a reservoir for cytotoxic T cells. Spleen T cells, which display a regulatory-like profile and transfer graft survival, are not able to prevent chronic rejection.

Combination of Donor-Specific Blood Transfusion With Anti-CD28 Antibody Synergizes to Prolong Graft Survival in Rat Liver Transplantation

Donor-specific blood transfusion (DST) has been shown to effectively induce tolerance to certain allografts. In addition, it is well known that blockade of costimulatory signals reduces the ability of T cells to respond to alloantigens, prolonging allograft survival in some transplant models. We assessed the effects of single or multiple DSTs in the absence or presence of anti-CD28 monoclonal antibodies (mAbs) on graft function and host survival in rat liver transplantation (LTx). Fully MHC-mismatched adult male Dark Agouti (DA) and Lewis (LEW) rats were used as donors and recipients, respectively. Heparinized DA blood was administered to naïve LEW rats 7 days before LTx [DST(−7d)], 14 and 7 days before LTx [DST(1×2)], twice a week for 2 weeks prior to LTx [DST(2×2)] and once a week for 4 weeks prior to LTx [DST(1×4)]. For some experiments, two different monoclonal antibodies (mAb) to rat CD28 (JJ316 and JJ319) were administered in combination with some DST treatments. We found that DST administration induced a time- and dose-dependent increase in host survival. Treatment of LEW rats with JJ316 or JJ319 mAb alone failed to prolong graft survival over untreated rats; however, the combination of DST(1×2) with JJ316 or JJ319 mAb induced indefinite survival at 100 days following surgery. We found that this protective effect was associated with increased numbers of splenic CD4 +CD45RC − but not CD4 +CD25 +foxp3 + T-cells in long-term survivors. Our data suggest that the combination of suboptimal DST with CD28 mAb induces donor-specific tolerance that correlates with enhanced numbers of regulatory T-cells.

Tolerogenic Protocol for Intestinal Transplantation

Transplantation is standard therapy for many patients suffering from kidney, liver, or heart failure. In contrast, transplantation of the intestine remains a high-risk procedure, which is performed in a minority of patients with short bowel syndrome. The difficulty is the strong alloimmune response caused by intestinal grafts and the complications of the profound immunosuppression. We tested a new clinical immunomodulatory protocol using donor-specific blood transfusion, a strategy that was popular before the introduction of cyclosporine and was recently shown to promote development of regulatory cells. Low-dose steroids and low-dose tacrolimus were administered based on previous observations that tolerance requires an intact immune system, that overimmunosuppression is counterproductive, and that high doses of calcineurin inhibitors block development of regulatory cells whereas low doses promote it. Finally, inflammation within the intestinal graft was minimized to reduce the additional stimulants that the innate immunity of the transplanted intestine exert on the adaptive immune response. Under this protocol, freedom from rejection was achieved in four consecutive intestinal transplant recipients using extremely low immunosuppression.

Treatment of Short Gut Syndrome With Early Living Related Small Bowel Transplantation

Aim To investigate the results of treating short bowel syndrome with an early living related small bowel transplantation (SBT). Methods A 17-year-old boy with a 20-cm-long residual intestine due to necrotic volvulus received an early living related SBT from his mother. Donor-specific blood transfusion was performed for 8 weeks before transplantation, each time for 50 mL every week. Cytomegalovirus status in both donor and recipient was negative. A 160-cm distal ileal segment was removed from the donor. The graft ilecolic artery and vein were anastomosed to the recipient’s infrarenal aorta and caval vein. The proximal end of the graft was anastomosed end-to-end to the residual recipient jejunum; the distal anastomosis, between the distal end of the graft and transverse colon. An ileostomy was also performed. Immunosuppression, infection prophylaxis, and antithrombotic and nutrition support were given postoperatively. Results The donor had an uneventful recovery. No technical complications were observed. The recipient was alive and well at 31 weeks after the operation. No graft rejection or infection was observed. He was off TPN 8 weeks after the operation and took low-fat food. The D-xylose test in the recipient was almost normal. Conclusions Early living related small intestine transplantation is a good treatment for short bowel syndrome.