Evidence of donor-specific cellular suppressor activity in donor-specific cell-mediated lympholysis unresponsiveness in renal transplant patients

Twenty patients with well-functioning kidney grafts from one-haplotype-mismatched related donors, were studied 1-10 years after transplantation (A). Another group of six patients were studied at various times after transplantation (B). The presence of donor-specific transplantation tolerance, using mixed lymphocyte culture (MLC) and cell-mediated lympholysis (CML) tests was investigated, as well as the possible existence of cells with suppressive activity. All recipients were transfused prior to transplantation and treated with conventional immunosuppression. The patients in group A showed MLC reactivity against donor and third-party cells, indicating a allogeneic response capacity. The CML activity against the donor was low, however, and remained low also following removal of adherent cells. The CML activity toward third-party cells was within the normal range of unmatched individuals. In group B, two of six recipients and high postoperative CML activity against the donor. Both recipients showed clinical signs of rejection. In the remaining four recipients, the antidonor CML reactivity one week after transplantation was lower than the preoperative level. The decrease was even more pronounced at 12 months, although the reactivity against third-party cells was unaltered. The CML reactivity from unrelated fourth-party individuals toward donors was suppressed when cells from recipients with long-term functioning kidneys were added to the cell cultures. The results suggest the presence of a donor-specific cellular suppressor mechanism underlying the donor-specific CML unresponsiveness in recipients with long-term-functioning kidney allografts.     

Differential effects of donor-specific alloantibody

Alloantigen exposure typically provokes an adaptive immune response that can foster rejection of transplanted organs, and these responses present the most formidable biological barrier to kidney transplantation. Although most cellular alloimmune responses can be therapeutically controlled with T-cell-specific immunosuppressants, humoral alloimmune responses remain relatively untamed. Importantly, humoral immunity, typically manifesting as allospecific antibody production, is increasingly recognized for its variable appearance after kidney transplantation. Indeed, the appearance of alloantibody can herald the onset of rapid and destructive antibody-mediated rejection or have no demonstrable acute effects. The factors determining the end result of alloantibody formation remain poorly understood. This review will discuss the breadth of alloantibody responses seen in clinical kidney transplantation and provide an overview of potential factors explaining the phenotypic variability associated with humoral alloimmunity. We propose several avenues ripe for future investigation including the influence of innate immune components and the potential influence of heterologous immune responses in determining the ultimate clinical import of an alloantibody response.     

ABO-incompatible kidney transplantation with donor-specific skin graft

From November 3, 1975, to May 31, 1989, 711 (548 living-related and 163 cadavers) kidney transplantations were performed in our centers. In the final 2 years, 15 ABO-incompatible living related kidney transplantations were performed. In 4 cases, the recipient's blood groups was O and the donor's A1. In 3 cases the blood group of the recipient was A1 and the donor's AB, two patients were B with the donors A1 and the other 2 were O with donors B. The other 3 recipients group was B and the donors' were AB. The donors' and recipients' HLA-AB typing showed one haplotype matching in 12 and two haplotypes matching in 3 patients. The donors were mothers in 7 cases, sibling in 5, and father in 3 cases. At least 3 weeks before the renal transplantation, donor-specific skin grafts and subsequently splenectomy were performed on 9 recipients, but on 6 recipients without splenectomy. Following the skin graft, cross-match was done starting from the 15th day and then continued every week. The immunosuppression, which consisted of triple drugs (0.5 mg/kg prednisolone, 2 mg/kg cyclosporin-A and 2 mg/kg azathioprine) was followed by skin graft. Renal transplantation was performed according to cross-match and skin graft results, and all recipients prior to surgery received at least two sessions of plasmapheresis. Regular dose of immunosuppression that included triple drugs were used after the kidney transplantation and then Orthoclone OKT-3 and plasmapheresis were applied during the rejection episodes without bolus therapy. All patients were followed for 5 to 24 months (ave. 14,13 months).(ABSTRACT TRUNCATED AT 250 WORDS)     

Significance of donor-specific antibodies in acute rejection

Significant advances in recent years in the diagnosis of antibody-mediated graft rejection have led to the re-evaluation of humoral alloreactivity in organ transplantation. By introducing the "C4d-test" into the work-up of transplant biopsies, donor-specific antibodies were claimed to be directly involved in about 30% of acute rejection episodes. The diagnostic criteria for antibody-mediated rejections of renal grafts are now incorporated in the "Banff classification" as refined at a recent consensus conference. Capillary C4d is not always concordant with circulating anti-HLA-antibodies, even if these are assayed with improved techniques. Antibody absorption within the graft and antigens other than HLA, therefore, have to be considered. Effective therapy of humoral rejection is now available. Serial assessment of humoral alloreactivity also in the posttransplantation period is now mandatory to identify at-risk patients.     

Variability in donor-specific alloantibody production after transplantation

The role of de novo donor-specific alloantibodies (DSAs) in renal allograft injury is still unclear. The aims of this study were as follows: to assess the development of DSAs during the first year after transplantation, to determine the cause of DSA production, and to evaluate the association of DSA with allograft function. The study included 78 consecutive transplant recipients with negative cross-matches before transplantation. Recipient serum samples were assayed for DSA at 2 weeks as well as at 1, 3, 6, 9, and 12 months using a complement-dependent lymphocytotoxic (CDC) cross-match technique with donor lymphocytes. Among 545 cross-match tests performed after transplantation, there were 79 positive results. DSA appeared de novo in 44.8% of recipients: in 20 patients at 2 weeks; in 23 patients at 1 month; in 14 patients at 3 months; in 9 patients at 6 months; in 5 patients at 9 months; and in 8 patients at 12 months. Between month 3 and 9 after transplantation, DSA disappeared in 22 patients and appeared in 11 others. In 20 patients (57.1%) the appearance of DSA was associated with an acute rejection episode. In 11 of these, C4d deposition was found. In comparison with 43 patients without DSA, the serum creatinine levels during the first year after transplantation were significantly higher among patients with DSA. Transplant recipients produce antidonor alloantibodies. The highest rate occurs during the first month with the incidence diminishing at 3 months after transplantation. The development of DSAs in more than half of the patients was associated with rejection episodes. Patients with antidonor alloreactivity showed worse renal function.     

Lymphocytotoxic donor-specific response to fresh and stored blood

Transfusion of stored blood has been found to decrease the rate of antibody formation. Antigen immunogenicity and the recipient's immunoresponsiveness have a major role in the fate of the allograft. The combined effect of low immunogenicity and depressed responsiveness has been studied.     

The presence of donor-specific antibodies in renal transplantation

Determining the presence of anti-HLA antibodies before transplantation is an important factor to prevent loss of function among renal transplantations. In addition, recent studies have shown that not only the pretransplantation existence of anti-HLA antibody but also posttransplantation donor-specific antibodies (DSA) and non-donor-specific antibodies are significantly associated with allograft rejection or loss of graft function. This study presented DSA among patients after renal transplantation together with graft function and survival.     

Complement-fixing donor-specific anti-HLA antibodies and kidney allograft failure

Detection of donor-specific antibodies (DSA) has improved the risk classification and post-transplant evaluation of kidney recipients. Moreover, assessment of DSA C1q-binding ability has been shown to improve the individual risk classification of transplant patients for allograft loss, especially when detected after transplantation. The aim of this study was to evaluate the additional clinical impact of C1q-binding DSA detection in a population that was extensively monitored for DSA and MFI alterations. Forty-two kidney allograft recipients were followed-up at multiple time points for up to 5 years after transplantation for the presence of anti-HLA DSA-IgG total. The samples that were positive for these antibodies were retrospectively tested for the presence of complement-binding antibodies. Overall, 24 patients presented DSA, 29% (7) of which also produced complement-binding DSA. Compared to patients with non-C1q-binding DSA and non-sensitized patients, patients with C1q-binding DSA after transplantation had the lowest allograft survival rate at 5 years (p = 0.042) and showed a lower estimated glomerular filtration rate (based on the Modification of Diet in Renal Disease formula) during the post-transplant follow-up period (p = 0.01). Thus, post-transplant monitoring for complement-binding DSA is a useful tool for predicting individuals most at risk for allograft failure, and might also be beneficial for evaluation of immunosuppression regimens.     

De novo membranous nephropathy associated with donor-specific alloantibody

Abstract:  Recent evidence suggests that alloantibody may play an aetiological role in the pathogenesis of membranous glomerulopathy in native kidneys. There is an increased awareness of the significance of alloantibody on renal transplant outcome, particularly with the development of more sensitive assays. We describe a kidney transplant patient who developed de novo membranous glomerulopathy (DNMG) with heavy proteinuria in the context of a donor-specific alloantibody (DSA) directed against HLA DQ7. Proteinuria resolved and kidney function stabilized following treatment with mycophenolate mofetil and an angiotensin receptor blocker. The titre of the DSA fell in parallel with resolution of the proteinuria.
This is the first reported case of DNMG after kidney transplantation clearly associated with a DSA. We hypothesize that de novo membranous glomerulopathy may be an atypical manifestation of acute antibody-mediated damage. Cases of DNMG should be screened for alloantibody and the presence of alloantibody may influence the choice of therapy.     

Valve interstitial cells induce donor-specific T-cell anergy.

OBJECTIVES: Valve allografts produce an immune response, which can influence their performance. The exact role of the interaction between recipient T cells and the different cellular components of the donor valve in stimulating an immune response is not known. Therefore the T-cell response to valve endothelial and interstitial cells was investigated in vitro. METHODS: Valve endothelial and interstitial cells were characterized for cell-surface molecules before and after interferon gamma treatment by means of a panel of specific monoclonal antibodies and flow cytometry. The proliferative response of highly purified T lymphocytes was used to assess the immunogenicity of cultured valve endothelial and interstitial cells. This was further investigated by using a 2-step tolerance-induction protocol. RESULTS: Valve endothelial and interstitial cells express similar levels of human leukocyte antigens and adhesion and costimulatory molecules, which are either induced or upregulated after interferon gamma treatment. T-cell responses to endothelial cells were detected after interferon gamma treatment, but responses to interferon gamma-treated interstitial cells were not detected. This lack of response resulted in the induction of T-cell anergy, which was reversed by the presence of the costimulatory molecule B7-1. CONCLUSIONS: Although valve endothelial and interstitial cells express a similar range of cell-surface molecules, it is only the endothelial cells that are immunogenic. In addition, we have shown that these 2 cell types interact in a donor-specific manner to orchestrate the immune response and therefore may have clinical relevance in the allogeneic response of the heart valve recipients.     

Characterization of ABH-subtype donor-specific antibodies in ABO-A-incompatible kidney transplantation

ABO-incompatible (ABOi) transplantation requires preemptive antibody reduction; however, the relationship between antibody-mediated rejection (AMR) and ABO-antibodies, quantified by hemagglutination (HA), is inconsistent, possibly reflecting variable graft resistance to AMR or HA assay limitations. Using an ABH-glycan microarray, we quantified ABO-A antigen-subtype (A-subtype)-specific IgM and IgG in 53 ABO-O recipients of ABO-A kidneys, before and after antibody removal (therapeutic plasma exchange [TPE] or ABO-A-trisaccharide immunoadsorption [IA]) and 1-year posttransplant. IgM binding to all A-subtypes correlated highly (R² ≥ .90) and A-subtype antibody specificities was reduced equally by IA versus TPE. IgG binding to the A-subtypes (II–IV) expressed in kidney correlated poorly (.27 ≤ R² ≤ .69). Reduction of IgG specific to A-subtype-II was equivalent for IA and TPE, whereas IgG specific to A-subtypes-III/IV was not as greatly reduced by IA (p < .005). One-year posttransplant, IgG specific to A-II remained the most reduced antibody. Immunostaining revealed only A-II on vascular endothelium but A-subtypes II-III/IV on tubular epithelium. These results show that ABO-A-trisaccharide is sufficient for IgM binding to all A-subtypes; this is true for IgG binding to A-II, but not subtypes-III/IV, which exhibits varying degrees of specificity. We identify A-II as the major, but importantly not the sole, antigen relevant to treatment and immune modulation in adult ABO-A-incompatible kidney transplantation.     

Increase of donor-specific cytotoxic T lymphocyte precursors after transfusion

Cytotoxic T lymphocyte precursor (CTLp) frequencies were determined in the blood of 10 patients before and after transfusion. The male patients were selected from those on the waiting list for a heart or kidney transplantation, who had received no previous blood transfusions and had no panel-reactive antibodies. Both the limiting dilution curves obtained before as well as after transfusion were linear and applied to zero-order kinetics, indicating that only cytotoxic T cells were limiting in the assay. In 9 out of 10 patients CTLp frequencies against the blood donor antigens significantly increased (up to 107 times) compared to the CTLp frequencies measured before transplantation. The CTLp frequencies against controls, sharing no HLA antigens with the blood transfusion donor, were only slightly increased (up to 5 times) in 7 patients and decreased in 3.     

Variable response to donor-specific blood transfusion in the rat

In an attempt to study the generality of effect of donor-specific blood transfusions (DSBT) in inducing immunologic unresponsiveness, the survival rates of heart, pancreas, and skin allografts were compared in blood-pretreated animals. DSBT, when given in a single-dose or multiple-dose protocol, prolonged cardiac allograft survivals in some strain combinations (F----L, LBN----L), but not in others (BN----L, ACI----L, ACI----WF). Antilymphocyte serum further prolonged survivals in protocols in which blood pretreatment was effective, and proved capable of reversing a state of sensitization in rats treated with multiple small-volume transfusions. In no case did the protection afforded the cardiac allografts extend to pancreatic or skin allografts, even with the use of nonspecific immunosuppression and a weak histocompatibility barrier. Third-party cardiac allografts were not protected by the blood pretreatment, attesting to the specificity of the transfusion effect. Addition of azathioprine during the blood pretreatment neither interfered with nor significantly improved the results seen with transfusion alone. The graft prolongation that follows blood pretreatment appears to be influenced by many factors, such as donor-host histocompatibility, the specific tissue transplanted, the blood transfusion schedule, and the use of adjunctive immunosuppression--but presently it is an unpredictable phenomenon.     

The clinical impact of donor-specific antibodies in heart transplantation

Donor-specific antibodies (DSA) are integral to the development of antibody-mediated rejection (AMR). Chronic AMR is associated with high mortality and an increased risk for cardiac allograft vasculopathy (CAV). Anti-donor HLA antibodies are present in 3–11% of patients at the time of heart transplantation (HTx), with de novo DSA (predominantly anti-HLA class II) developing post-transplant in 10–30% of patients. DSA are associated with lower graft and patient survival after HTx, with one study suggesting a three-fold increase in mortality in patients who develop de novo DSA (dnDSA). DSA against anti-HLA class II, notably DQ, are at particularly high risk for graft loss. Although detection of DSA is not a criterion for pathologic diagnosis of AMR, circulating DSA are found in almost all cases of AMR. MFI thresholds of ~5000 for DSA against class I antibodies, 2000 against class II antibodies, or an overall cut-off of 5?6000 for any DSA, have been suggested as being predictive for AMR. There is no firm consensus on pre-transplant strategies to treat HLA antibodies, or for the elimination of antibodies after diagnosis of AMR. Minimizing the risk of dnDSA is rational but data on risk factors in HTx are limited. The effect of different immunosuppressive regimens is largely unexplored in HTx, but studies in kidney transplantation emphasize the importance of adherence and maintaining adequate immunosuppression. One study has suggested a reduced risk for dnDSA with rabbit antithymocyte globulin induction. Management of DSA pre- and post-HTx varies but typically most centers rely on a plasmapheresis or immunoadsorption, with or without rituximab and/or intravenous immunoglobulin. Based on the literature and a multi-center survey, an algorithm for a suggested surveillance and therapeutic strategy is provided.