Mechanisms involved in antithymocyte globulin immunosuppressive activity in a nonhuman primate model

Anti-thymocyte globulin for treatment of T-cell-mediated allograft rejection

Anti-thymocyte globulin (ATG) is a pivotal immunosuppressive therapy utilized in the management of T-cell-mediated rejection and steroid-resistant rejection among renal transplant recipients. Commercially available as Thymoglobulin (rabbit-derived, Sanofi, United States), ATG-Fresenius S (rabbit-derived), and ATGAM (equine-derived, Pfizer, United States), these formulations share a common mechanism of action centered on their interaction with cell surface markers of immune cells, imparting immunosuppressive effects. Although the prevailing mechanism predominantly involves T-cell depletion via the com plement-mediated pathway, alternate mechanisms have been elucidated. Optimal dosing and treatment duration of ATG have exhibited variance across ran domised trials and clinical reports, rendering the establishment of standardized guidelines a challenge. The spectrum of risks associated with ATG administration spans from transient adverse effects such as fever, chills, and skin rash in the acute phase to long-term concerns related to immunosuppression, including susceptibility to infections and malignancies. This comprehensive review aims to provide a thorough exploration of the current understanding of ATG, encom passing its mechanism of action, clinical utility in the treatment of acute renal graft rejections, specifically steroid-resistant cases, efficacy in rejection episode reversal, and a synthesis of findings from different eras of maintenance immunosuppression. Additionally, it delves into the adverse effects associated with ATG therapy and its impact on long-term graft function. Furthermore, the review underscores the existing gaps in evidence, particularly in the context of the Banff classification of rejections, and highlights the challenges faced by clinicians when navigating the available literature to strike the optimal balance between the risks and benefits of ATG utilization in renal transplantation.

Chimerism-based Tolerance Induction in Clinical Transplantation: Its Foundations and Mechanisms

Hematopoietic chimerism remains the most promising strategy to bring transplantation tolerance into clinical routine. The concept of chimerism-based tolerance aims to extend the recipient's mechanisms of self-tolerance (ie, clonal deletion, anergy, and regulation) to include the tolerization of donor antigens that are introduced through the cotransplantation of donor hematopoietic cells. For this to be successful, donor hematopoietic cells need to engraft in the recipient at least temporarily. Three pioneering clinical trials inducing chimerism-based tolerance in kidney transplantation have been published to date. Within this review, we discuss the mechanisms of tolerance that are associated with the specific therapeutic protocols of each trial. Recent data highlight the importance of regulation as a mechanism that maintains tolerance. Insufficient regulatory mechanisms are also a likely explanation for situations of tolerance failure despite persisting donor chimerism. After decades of preclinical development of chimerism protocols, mechanistic data from clinical trials have recently become increasingly important. Better understanding of the required mechanisms for tolerance to be induced in humans will be a key to design more reliable and less invasive chimerism protocols in the future.

Graft-versus-host disease: teaching old drugs new tricks at less cost

Graft-versus-host disease (GVHD) remains a major cause of morbidity and mortality after allogeneic stem cell transplantation (SCT). Currently, more patients can receive SCT. This is attributed to the use of reduced intensity regimens and the use of different GVHD prophylaxis that breaks the barrier of human leukocyte antigen, allowing an increase in the donor pool. Once an area with relatively few clinical trial options, there has been an increase in interest in GVHD prophylaxis and treatment, which has led to many US Food and Drug Administration (FDA) approvals. Although there is considerable excitement over novel therapies, many patients may not have access to them due to geographical or other resource constraints. In this review article, we summarize the latest evidence on how we can continue to repurpose drugs for GVHD prophylaxis and treatment. Drugs covered by our review include those that have been FDA approved for other uses for at least 15 years (since 2008); thus, they are likely to have generic equivalents available now or in the near future.

LIS1, a glyco-humanized swine polyclonal anti-lymphocyte globulin, as a novel induction treatment in solid organ transplantation

Anti-thymocyte or anti-lymphocyte globulins (ATGs/ALGs) are immunosuppressive drugs used in induction therapies to prevent acute rejection in solid organ transplantation. Because animal-derived, ATGs/ALGs contain highly immunogenic carbohydrate xenoantigens eliciting antibodies that are associated with subclinical inflammatory events, possibly impacting long-term graft survival. Their strong and long-lasting lymphodepleting activity also increases the risk for infections. We investigated here the in vitro and in vivo activity of LIS1, a glyco-humanized ALG (GH-ALG) produced in pigs knocked out for the two major xeno-antigens αGal and Neu5Gc. It differs from other ATGs/ALGs by its mechanism of action excluding antibody-dependent cell-mediated cytotoxicity and being restricted to complement-mediated cytotoxicity, phagocyte-mediated cytotoxicity, apoptosis and antigen masking, resulting in profound inhibition of T-cell alloreactivity in mixed leucocyte reactions. Preclinical evaluation in non-human primates showed that GH-ALG dramatically reduced CD4+ (p=0.0005,***), CD8+ effector T cells (p=0.0002,***) or myeloid cells (p=0.0007,***) but not T-reg (p=0.65, ns) or B cells (p=0.65, ns). Compared with rabbit ATG, GH-ALG induced transient depletion (less than one week) of target T cells in the peripheral blood (<100 lymphocytes/L) but was equivalent in preventing allograft rejection in a skin allograft model. The novel therapeutic modality of GH-ALG might present advantages in induction treatment during organ transplantation by shortening the T-cell depletion period while maintaining adequate immunosuppression and reducing immunogenicity.

Anti‐thymocyte globulin‐mediated immunosenescent alterations of T cells in kidney transplant patients

Objectives

Kidney transplant (KT) is the most effective treatment for end‐stage renal disease. The immunosuppressant anti‐thymocyte globulin (ATG) has been applied for induction therapy to reduce the risk of acute transplant rejection for patients at high immunological risk. Despite its putative role in replicative stress during immune reconstitution, the effects of ATG on T‐cell immunosenescent changes remain to be understood.

Methods

Phenotypic and functional features of senescent T cells were examined by flow cytometry in 116 healthy controls (HC) and 95 KT patients for comparative analysis according to ATG treatment and CMV reactivation. The TCR repertoire was analysed in peripheral blood mononuclear cells (PBMCs) of KT patients.

Results

T cells of KT patients treated with ATG (ATG⁺) show typical immunosenescent features, accumulation of CD28⁻, CD85j⁺ or CD57⁺ T cells, and imbalance of functional T‐cell subsets, compared with untreated KT patients (ATG⁻). Plasma IL‐15 and CMV‐IgG levels were higher in KT patients than in HCs, and the IL‐15 level positively correlated with the frequency of CD28⁻ T cells in KT patients. ATG⁺ patients had a higher prevalence of CMV reactivation, which is associated with an increased frequency of CD28⁻ T cells. As a result, ATG⁺ patients had expanded CMV‐specific T cells and decreased TCR diversity. However, proliferation, cytokine‐producing capacity and polyfunctionality of T cells were preserved in ATG⁺ patients.

Conclusion

Our findings suggest that ATG treatment contributes to the accumulation of senescent T cells, which may have lifelong clinical implications in KT patients. Thus, these patients require long‐term and comprehensive immune monitoring.

Impact of Anti-T-lymphocyte globulin dosing on GVHD and Immune reconstitution in matched unrelated myeloablative peripheral blood stem cell transplantation

Data on the influence of different Anti-lymphocyte globulin (ATLG) doses on graft versus host disease (GVHD) incidence and immune reconstitution in matched unrelated (MUD) allogeneic Stem cell transplantation (allo-SCT) is limited. This retrospective study conducted at the University Medical-Center Hamburg compares GVHD and Immune reconstitution after myeloablative MUD (HLA 10/10) PBSC allogeneic stem cell transplant between 30 mg/Kg (n = 73) and 60 mg/Kg (n = 216) ATLG. Detailed phenotypes of T, B natural killer (NK), natural killer T (NKT) cells were analyzed by multicolor flow at day 30, 100, and 180 posttransplant. Neutrophil and platelet engraftments were significantly delayed in the 60 mg/kg group with a higher Cumulative incidence of Infections (67% vs 75% p = 0.049) and EBV (21% vs 41% p = 0.049) reactivation at day 100 in this group. In the 30 mg/kg group, we observed a faster reconstitution of naïve-B cells (p < 0.0001) and γδ T cells (p = 0.045) at day+30 and a faster naïve helper T-cell (p = 0.046), NK-cells (p = 0.035), and naïve B-cell reconstitution (p = 0.009) at day+180. There were no significant differences in aGVHD, cGVHD, NRM, RI, PFS, and OS between the groups. The choice of ATLG dose has significant impact on IR but not on GVHD after MUD-allo-SCT. Higher doses are associated with delayed engraftment and increased infections.

The Influence of Microenvironment on Survival of Intraportal Transplanted Islets

Clinical islet transplantation has the potential to cure type 1 diabetes. Despite recent therapeutic success, it is still uncommon because transplanted islets are damaged by multiple challenges, including instant blood mediated inflammatory reaction (IBMIR), inflammatory cytokines, hypoxia/reperfusion injury, and immune rejection. The transplantation microenvironment plays a vital role especially in intraportal islet transplantation. The identification and targeting of pathways that function as "master regulators" during deleterious inflammatory events after transplantation, and the induction of immune tolerance, are necessary to improve the survival of transplanted islets. In this article, we attempt to provide an overview of the influence of microenvironment on the survival of transplanted islets, as well as possible therapeutic targets.

Effects of Reduced-Dose Anti-Human T-Lymphocyte Globulin on Overall and Donor-Specific T-Cell Repertoire Reconstitution in Sensitized Kidney Transplant Recipients

Background

Pre-sensitized kidney transplant recipients have a higher risk for rejection following kidney transplantation and therefore receive lymphodepletional induction therapy with anti-human T-lymphocyte globulin (ATLG) whereas non-sensitized patients are induced in many centers with basiliximab. The time course of lymphocyte reconstitution with regard to the overall and donor-reactive T-cell receptor (TCR) specificity remains elusive.

Methods/Design

Five kidney transplant recipients receiving a 1.5-mg/kg ATLG induction therapy over 7 days and five patients with 2 × 20 mg basiliximab induction therapy were longitudinally monitored. Peripheral mononuclear cells were sampled pre-transplant and within 1, 3, and 12 months after transplantation, and their overall and donor-reactive TCRs were determined by next-generation sequencing of the TCR beta CDR3 region. Overall TCR repertoire diversity, turnover, and donor specificity were assessed at all timepoints.

Results

We observed an increase in the donor-reactive TCR repertoire after transplantation in patients, independent of lymphocyte counts or induction therapy. Donor-reactive CD4 T-cell frequency in the ATLG group increased from 1.14% + -0.63 to 2.03% + -1.09 and from 0.93% + -0.63 to 1.82% + -1.17 in the basiliximab group in the first month. Diversity measurements of the entire T-cell repertoire and repertoire turnover showed no statistical difference between the two induction therapies. The difference in mean clonality between groups was 0.03 and 0.07 pre-transplant in the CD4 and CD8 fractions, respectively, and was not different over time (CD4: F(1.45, 11.6) = 0.64 p = 0.496; CD8: F(3, 24) = 0.60 p = 0.620). The mean difference in R20, a metric for immune dominance, between groups was -0.006 in CD4 and 0.001 in CD8 T-cells and not statistically different between the groups and subsequent timepoints (CD4: F(3, 24) = 0.85 p = 0.479; CD8: F(1.19, 9.52) = 0.79 p = 0.418).

Conclusion

Reduced-dose ATLG induction therapy led to an initial lymphodepletion followed by an increase in the percentage of donor-reactive T-cells after transplantation similar to basiliximab induction therapy. Furthermore, reduced-dose ATLG did not change the overall TCR repertoire in terms of a narrowed or skewed TCR repertoire after immune reconstitution, comparable to non-depletional induction therapy.

The Effects of Different Induction Regimes on Serial Lymphocyte Subsets in Kidney Transplant Recipients: A Single Tertiary Center Experience

BACKGROUND

Immunosuppressive therapy is the backbone of kidney transplantation in preventing acute rejection. T-cell depletion after doses of thymoglobulin is dose-dependent, as are their side effects. At the same time, basiliximab and other maintenance immunosuppressive drugs act at different signals on T lymphocytes. Therefore, studying the pattern of lymphocyte subset depletion depending on the induction regime given at transplantation could be an added tool in managing post-transplant recipients.

METHODOLOGY

This prospective observational study recruited kidney transplant recipients from August 2019 through April 2021 at the University of Malaya Medical Centre. Blood tests for lymphocyte subsets were taken at pre-transplant, 1 week, 1 month, 3 months, and 6 months post-transplantation. At transplantation, recipients received either basiliximab, low-dose thymoglobulin (cumulative dose: 1.5 mg/kg), or standard-dose thymoglobulin (cumulative dose: 5 mg/kg).

RESULTS

A total of 39 patients were recruited: 38.5% received basiliximab (15 of 39), 15.4% received low-dose thymoglobulin (6 of 39), and 46.2% received standard-dose thymoglobulin (18 of 39). Absolute lymphocyte counts 1 week post-transplantation were 1.5 ± 0.84 × 10⁹/L for basiliximab, 0.7 ± 0.57 × 10⁹/L for low-dose thymoglobulin, and 0.1 ± 0.08 × 10⁹/L for standard-dose thymoglobulin (P < .001). The CD4+ and CD8+ counts were severely depleted in the standard-dose thymoglobulin group, with a statistically significant differenceup to 6 months post-transplantation. In the low-dose thymoglobulin group, the CD4+ and CD8+ counts were depleted at 1 week post-transplantation and recovered at 1 month post-transplantation. There was no difference in allograft function and incidence of allograft rejection across groups.

CONCLUSIONS

The effects on lymphocyte counts, CD4+ and CD8+, vary depending on the type and dose of induction immunosuppression. This could be a guiding tool in managing immunosuppression post-transplantation depending on the patient's immunologic risk.

Clinical effect of rabbit anti-thymocyte globulin for chronic active antibody-mediated rejection after kidney transplantation

Chronic active antibody-mediated rejection (CAAMR) is a frequent cause of late graft loss. However, effective treatment for CAAMR after kidney transplantation has not yet been established. Here, we present the case of a kidney transplant recipient who recovered from CAAMR after administration of rabbit anti-thymocyte globulin. A 61-year-old man underwent ABO-compatible living-donor kidney transplantation for end-stage kidney disease; the kidney was donated by his wife. Five years after the transplant, the patient's serum creatinine level and urine protein-to-creatinine ratio increased. He was subsequently diagnosed with CAAMR based on the kidney allograft biopsy and the presence of donor-specific human leukocyte antigen antibodies. Rabbit anti-thymocyte globulin treatment was administered following steroid pulse therapy. Subsequently, his serum creatinine levels and urine protein to creatinine ratio improved. There was also an improvement in the pathological findings seen on biopsy and the mean fluorescence intensity of donor-specific antibodies. In conclusion, this report describes the case of a kidney transplant recipient who developed CAAMR, treated using rabbit anti-thymocyte globulin. This strategy might be a viable treatment option for CAAMR after a kidney transplant.

Rabbit antithymocyte globulin dose and early subclinical and clinical rejections in kidney transplantation

Antithymocyte globulin (ATG) is a commonly used induction agent in kidney transplant recipients. However, the optimal dosing has not been well defined. Our protocol aims for a 5-6 mg/kg cumulative dose. It is unclear if a dose lower than 5 mg/kg is associated with more rejection. We performed a retrospective cohort study of patients who received a kidney transplant at our center between January 1, 2013 and December 31, 2016. Primary outcome was biopsy proven acute rejection (clinical and subclinical) in the first six months after kidney transplant. CMV viremia in high risk(D+/R-) recipients and BK viremia was compared as a secondary endpoint. Of the 543 patients, the Low Dose (LD) group (n = 56) received <5 mg/kg ATG and Regular Dose (RD) group (n = 487) received ≧5 mg/kg. Patients in RD were more sensitized (higher PRA and CPRA). LD received a dose of 4 ± 1.1 mg/kg ATG whereas RD received 5.6 ± 0.3 mg/kg ATG (p < 0.001). TCMR(Banff 1A or greater) was present in 34% of patients in LD vs. 22% in RD (p = 0.04) (OR 2.1;95%CI 1.12-3.81;p = 0.019). There was no difference in the incidence of CMV or BK viremia. ATG doses lower than 5 mg/kg may be associated with a heightened risk of rejection despite a low degree of sensitization. This article is protected by copyright. All rights reserved.

Induction Therapy and Therapeutic Antibodies

Prevention of allograft rejection is one of the crucial goals in solid organ transplantation to ensure durability of the graft and is chiefly mediated by cellular and humoral pathways targeting cell surface alloantigens. The risk of rejection is highest in the first post-transplant year and wanes with time albeit the risk always exists and varies with the type of organ transplanted. Induction therapies refer to the use of high-intensity immunosuppression in the immediate post-operative period to mitigate the highest risk of rejection. This term encompasses chiefly the use of antibody therapies directed against one of the key pathways in T-cell activation or abrogating effects of circulating alloantibodies. These antibodies carry more potent immunomodulatory effect than maintenance immunosuppressive therapy alone and many of them lead to durable immune cell depletion. A variety of monoclonal and polyclonal antibodies have been utilized for use not only for induction therapy, but also for treatment of allograft rejection when it occurs and as components of desensitization therapy before and after transplantation to modulate circulating alloantibodies.

Anti-thymoglobulin induction improves neonatal porcine xenoislet engraftment and survival

Porcine islet xenotransplantation is a viable strategy to treat diabetes. Its translation has been limited by the pre-clinical development of a clinically available immunosuppressive regimen. We tested two clinically relevant induction agents in a non-human primate (NHP) islet xenotransplantation model to compare depletional versus nondepletional induction immunosuppression. Neonatal porcine islets were isolated from GKO or hCD46/GKO transgenic piglets and transplanted via portal vein infusion in diabetic rhesus macaques. Induction therapy consisted of either basiliximab (n = 6) or rhesus-specific anti-thymocyte globulin (rhATG, n = 6), combined with a maintenance regimen using B7 costimulation blockade, tacrolimus with a delayed transition to sirolimus, and mycophenolate mofetil. Xenografts were monitored by blood glucose levels and porcine C-peptide measurements. Of the six receiving basiliximab induction, engraftment was achieved in 4 with median graft survival of 14 days. All six receiving rhATG induction engrafted with significantly longer xenograft survival at 40.5 days (P = 0.03). These data suggest that depletional induction provides superior xenograft survival to nondepletional induction, in the setting of a costimulation blockade-based maintenance regimen.

The impact of different doses of antithymocyte globulin conditioning on immune reconstitution upon hematopoietic stem cell transplantation

INTRODUCTION

Anti-thymocyte globulin (ATG) is used prior to allogeneic hematopoietic stem cell transplantation (allo-HSCT) for graft-versus-host disease (GVHD) prophylaxis. Two different ATG doses (7.5 or 10 mg/kg) were evaluated in comparison with a group without ATG therapy.

METHODS

We retrospectively analyzed 132 patients who were transplanted with HSCT without ATG (non-ATG), or who received 7.5 mg/kg ATG (ATG-7.5) or 10 mg/kg ATG (ATG-10) prior to transplantation. The immune cells (CD3⁺CD4⁺ T cells, CD3⁺CD8⁺ T cells, CD19⁺ B cells and CD16⁺CD56⁺ NK cells) were examined in peripheral blood every three months post-HSCT for 12 months.

RESULTS

Compared with non-ATG group, combined ATG-7.5/ATG-10 groups had significantly lower CD3⁺CD4⁺ T cells and higher CD3⁺CD8⁺ T cells at 3, 6, 9, 12 months post-HSCT; thus, displaying a lower CD4/CD8 ratio in the ATG groups compared to non-ATG group. The ratio of CD19⁺ B cells was statistically lower (at 3rd month, p = .014; at 6th month, p = .025) in combined ATG-7.5/ATG-10 groups at 3 and 6 months post-HSCT, but not at 9 and 12 months after HSCT. The ratios of CD3⁺CD4⁺ T cells, CD3⁺CD8⁺ T cells, CD19⁺ B cells and CD16⁺CD56⁺ NK cells were similar between the ATG-7.5 and ATG-10 groups at all examined time points. The overall survival (OS), progression-free survival (PFS), relapse and acute GVHD (aGVHD) were comparable among recipients without ATG therapy and with ATG-7.5 or/and ATG-10 therapies. Multivariate analysis revealed that immune cells ratios were not independent factors affecting prognosis.

CONCLUSION

The ATG therapy at higher and lower doses led to a delayed reconstitution of T cells and the inversion of CD4/CD8 ratio for at least one year after HSCT.

End-Stage Renal Disease-Related Accelerated Immune Senescence: Is Rejuvenation of the Immune System a Therapeutic Goal?

End-stage renal disease (ESRD) patients exhibit clinical features of premature ageing, including frailty, cardiovascular disease, and muscle wasting. Accelerated ageing also concerns the immune system. Patients with ESRD have both immune senescence and chronic inflammation that are resumed in the so-called inflammaging syndrome. Immune senescence is particularly characterised by premature loss of thymic function that is associated with hyporesponsiveness to vaccines, susceptibility to infections, and death. ESRD-related chronic inflammation has multiple causes and participates to accelerated cardiovascular disease. Although, both characterisation of immune senescence and its consequences are relatively well-known, mechanisms are more uncertain. However, prevention of immune senescence/inflammation or/and rejuvenation of the immune system are major goal to ameliorate clinical outcomes of ESRD patients.

Immunosuppressive drugs modes of action

The innate and adaptive immune systems work as a complex interplay between different cell types, involving cytokines and chemokines mediating extracellular and paracrine effects. At the intracellular level, the inflammatory cascade is mediated by multifaceted processes that have been better described in the last 10 years. Immunosuppressive agents available in clinical practice act at different points of those cascades at the intracellular or extracellular level. Those drugs can mediate their effects on one or more cell types finally limiting inflammation and immune responses to antigens. Every immunosuppressive agent is characterized by intrinsic toxicity and side effects that may be due to the same therapeutic pathways or to off-target secondary effect of each molecule. We will here review the mechanisms of action of the most widely used immunosuppressive agents in the field of solid organ transplantation and autoimmune disorders, describing the mechanisms underlying both the therapeutic and secondary effects.

IL-7 and IL-15 Levels Reflect the Degree of T Cell Depletion during Lymphopenia and Are Associated with an Expansion of Effector Memory T Cells after Pediatric Hematopoietic Stem Cell Transplantation

Differentially and functionally distinct T cell subsets are involved in the development of complications after allogeneic hematopoietic stem cell transplantation (HSCT), but little is known about factors regulating their recovery after HSCT. In this study, we investigated associations between immune-regulating cytokines, T cell differentiation, and clinical outcomes. We included 80 children undergoing allogeneic HSCT for acute leukemia using bone marrow or peripheral blood stem cells grafted from a matched sibling or unrelated donor. Cytokines (IL-7, IL-15, IL-18, SCF, IL-6, IL-2, and TNF-α) and active anti-thymocyte globulin (ATG) levels were longitudinally measured along with extended T cell phenotyping. The cytokine profiles showed a temporary rise in IL-7 and IL-15 during lymphopenia, which was strongly dependent on exposure to active ATG. High levels of IL-7 and IL-15 from graft infusion to day +30 were predictive of slower T cell recovery during the first 2 mo post-HSCT; however, because of a major expansion of memory T cell stages, only naive T cells remained decreased after 3 mo (p < 0.05). No differential effect was seen on polarization of CD4⁺ T cells into Th1, Th2, or Th17 cells or regulatory T cells. Low levels of IL-7 and IL-15 at day +14 were associated with acute graft-versus-host disease grades II-IV in ATG-treated patients (p = 0.0004 and p = 0.0002, respectively). Children with IL-7 levels comparable to healthy controls at day +14 post-HSCT were less likely to develop EBV reactivation posttransplant. These findings suggest that quantification of IL-7 and IL-15 may be useful as biomarkers in assessing the overall T cell depletion and suggest a potential for predicting complications after HSCT.

A comparative study of human-and rhesus-specific antithymocyte globulins in Rhesus macaques

Rabbit antithymocyte globulin (RATG) preparations are widely used in transplantation. They are developed in vivo against thymocytes and contain polyclonal antibodies specific for myriad cellular targets. The rhesus monkey is commonly used as a preclinical transplant model, but the fidelity of commercially available human-specific RATGs to anticipate the effects of RATGs in rhesus has not been established. We therefore developed two rhesus-specific ATGs (rhATG) and compared them to human-specific RATG (huATG, Thymoglobulin^® ) in rhesus monkeys, assessing the magnitude and phenotype of depletion peripherally and in lymph nodes. Four primates were assigned to each group and received 20 mg/kg of drug. Depletion, repopulation, and changes in lymphocyte subsets were evaluated in peripheral blood and lymph nodes by flow cytometry over four months. We observed similar qualitative changes in lymphocyte subsets, but a generally more profound depletion with huATG compared to either rhATG. Peripheral homeostatic proliferation rather than thymic output was the major mechanism for repopulation with all RATGs. Repopulation was slower but qualitatively similar when examining RATGs in additional animals receiving concomitant chronic immunosuppression. Depletional induction is similar to human- and rhesus-specific RATGs in rhesus macaques. Both rhesus- and human-specific agents appear appropriate for preclinical modeling of clinical RATG use.

Rabbit antithymocyte globulin induces human lymphocyte activation, proliferation, and apoptosis in the absence of complement: an experimental study

Rabbit antithymocyte globulin (rATG) has become the first choice for induction therapy in HLA-presensitized patients undergoing organ transplantation. Meanwhile, complement inhibitors have been approved for preventing or treating antibody-mediated rejection in these patients. The biological effects of rATG on lymphocytes in cases of complement deficiency or significant inhibition are not yet clear. We measured lymphocyte activation, proliferation, and apoptosis in response to rATG treatment in the absence of complement. T-cell subsets were analyzed transcriptomically features to rATG stimulation. Activation-related phenotypes on T cells were determined in patients after rATG administration. We found that rATG treatment led to lymphocyte activation and proliferation in vitro without the addition of complement. A dose-dependent apoptosis in rATG-treated lymphocytes was detected, which was partially caspase-3-dependent but Fas/FasL-independent. T cells were more sensitive to rATG stimulation than were non-T cells. Both CD4⁺ T cells and CD8⁺ T cells upregulated a series of genes related to cell activation, cytokine production and apoptosis to rATG stimulation. CD69 and CD25 levels in surviving T cells were increased in patients after rATG administration. These findings indicate that rATG can stimulate lymphocyte activation, proliferation, and apoptosis in the absence of complement. Biologic effects of rATG other than complement-dependent cytotoxicity need to be concerned.

Safety and effectiveness of kidney transplantation using a donation after brain death donor with acute kidney injury: a retrospective cohort study

The use of kidneys from donation after brain death (DBD) donors with acute kidney injury (AKI) is a strategy to expand the donor pool. The aim of this study was to evaluate how kidney transplantation (KT) from a donor with AKI affects long-term graft survival in various situations. All patients who underwent KT from DBD donors between June 2003 and April 2016 were retrospectively reviewed. The KDIGO (Kidney Disease: Improving Global Outcomes) criteria were used to classify donor AKI. The cohort included 376 donors (no AKI group, n = 117 [31.1%]; AKI group n = 259 [68.9%]). Death-censored graft survival was similar according to the presence of AKI, AKI severity, and the AKI trend (p = 0.929, p = 0.077, and p = 0.658, respectively). Patients whose donors had AKI who received using low dose (1.5 mg/kg for three days) rabbit anti-thymocyte globulin (r-ATG) as the induction agent had significantly superior death-censored graft survival compared with patients in that group who received basiliximab (p = 0.039). AKI in DBD donors did not affect long-term death-censored graft survival. Low-dose r-ATG may be considered as an induction immunosuppression in recipients receiving kidneys with AKI because it showed better graft survival than basiliximab.

Combined low-dose everolimus and low-dose tacrolimus after Alemtuzumab induction therapy: a randomized prospective trial in lung transplantation

Background

Long-term outcomes of lung transplantation are severely affected by comorbidities and development of chronic rejection. Among the comorbidities, kidney insufficiency is one of the most frequent and it is mainly caused by the cumulative effect of calcineurin inhibitors (CNIs). Currently, the most used immunosuppression protocols worldwide include induction therapy and a triple-drug maintenance immunosuppression, with one calcineurin inhibitor, one anti-proliferative drug, and steroids. Our center has pioneered the use of alemtuzumab as induction therapy, showing promising results in terms of short- and long-term outcomes. The use of alemtuzumab followed by a low-dose double drug maintenance immunosuppression, in fact, led to better kidney function along with excellent results in terms of acute rejection, chronic lung allograft dysfunction, and survival (Benazzo et al., PLoS One 14(1):e0210443, 2019). The hypothesis driving the proposed clinical trial is that de novo introduction of low-dose everolimus early after transplantation could further improve kidney function via a further reduction of tacrolimus. Based on evidences from kidney transplantation, moreover, alemtuzumab induction therapy followed by a low-dose everolimus and low-dose tacrolimus may have a permissive action on regulatory immune cells thus stimulating allograft acceptance.

Methods

A randomized prospective clinical trial has been set up to answer the research hypothesis. One hundred ten patients will be randomized in two groups. Treatment group will receive the new maintenance immunosuppression protocol based on low-dose tacrolimus and low-dose everolimus and the control group will receive our standard immunosuppression protocol. Both groups will receive alemtuzumab induction therapy. The primary endpoint of the study is to analyze the effect of the new low-dose immunosuppression protocol on kidney function in terms of eGFR change. The study will have a duration of 24 months from the time of randomization. Immunomodulatory status of the patients will be assessed with flow cytometry and gene expression analysis.

Discussion

For the first time in the field of lung transplantation, this trial proposes the combined use of significantly reduced tacrolimus and everolimus after alemtuzumab induction. The new protocol may have a twofold advantage: (1) further reduction of nephrotoxic tacrolimus and (2) permissive influence on regulatory cells development with further reduction of rejection episodes.

Trial registration

EUDRACT Nr 2018-001680-24. Registered on 15 May 2018

Immunosuppressive Agents and Infectious Risk in Transplantation: Managing the "Net State of Immunosuppression"

Successful solid organ transplantation reflects meticulous attention to the details of immunosuppression, balancing risks for graft rejection against risks for infection. The 'net state of immune suppression' is a conceptual framework of all factors contributing to infectious risk. Assays which measure immune function in the immunosuppressed transplant recipient relative to infectious risk and allograft function are lacking. The best measures of integrated immune function may be quantitative viral loads to assess the individual's ability to control latent viral infections. Few studies address adjustment of immunosuppression during active infections. Thus, confronted with infection in solid organ recipients, the management of immunosuppression is based largely on clinical experience. This review examines known measures of immune function and the immunologic effects of common immunosuppressive drugs and available studies reporting modification of drug regimens for specific infections. These data provide a conceptual framework for the management of immunosuppression during infection in organ recipients.

Lower Platelet Count Following Rabbit Antithymocyte Globulin Induction Is Associated With Less Acute Cellular Rejection in Heart Transplant Recipients

BACKGROUND

Unlike lymphodepletion, a decrease in platelet count following induction immunosuppressive therapy with polyclonal rabbit antithymocyte globulin (rATG) is deemed as an adverse event. However, this phenomenon may represent a particular rATG antirejection mechanism.

METHODS

This retrospective single-center study included 156 patients who received a heart transplant (HTx) between 2010 and 2018. All patients received rATG induction therapy for 5 days. Absolute lymphocyte count (ALC) and platelet counts were assessed on days 0, 7, and 14 following HTx. The primary outcome of the study was the first occurrence of acute cellular rejection (ACR) defined as grade ≥ 1B within 24 months after HTx.

RESULTS

Both ALC and platelet counts decreased rapidly after induction. During the 24-month follow-up period, 17% of patients had ACR. Patients with ACR had significantly higher platelet count on day 7 (145 vs 104, P < .001) and higher ALC on day 14 (162 vs 130, P = .035) than those without rejection. Patients in the highest platelet count quartile showed more ACR (50% in quartile 4 vs 0% in quartile 1, P = .006) as well as a higher cumulative total rejection score. Univariate analysis showed that ACR was associated with platelet count on day 7, recipient age, and pretransplant cytomegalovirus IgG serology. In multivariable regression analysis, platelet count on day 7 was the most accurate predictor of ACR.

CONCLUSIONS

Lower platelet count after induction with rATG is associated with less ACR. This suggests platelet involvement in antirejection mechanisms of rATG and a possible rationale for targeting platelets in future immunosuppressive strategies.

T Lymphocytes in Acute Kidney Injury and Repair

Innate and adaptive immune systems participate in the pathogenesis of acute kidney injury (AKI). Considerable data from different research teams have shown the importance of T lymphocytes in the pathophysiology of AKI and, more recently, prevention and repair. T cells can generate or resolve inflammation by secreting specific cytokines and growth factors as well as interact with other immune and stromal cells to induce kidney injury or promote tissue repair. There also are emerging data on the role of T cells in the progression of AKI to chronic kidney disease and organ cross-talk in AKI. These data set the stage for immunomodulatory therapies for AKI. This review focuses on the major populations of T lymphocytes and their roles as mediators for AKI and repair.

[Premature immune senescence and chronic kidney disease: Update and perspectives]

Immune senescence is associated with age-related diseases (i.e. infectious disease, cardiovascular diseases and cancers). Chronic kidney disease patients die prematurely when compared with general population, because of a higher occurrence of infections, cardiovascular events and cancer. These diseases are commonly observed in the elderly population and frequently associated with immune senescence. Indeed, chronic kidney disease causes a premature aging of the T lymphocyte compartment, widely related to a decrease in thymic function, a phenomenon that plays a key role in the onset of age-related diseases in chronic kidney disease patients. The degree of immune senescence also influences patients' outcome after renal transplantation, particularly the risk of acute rejection and infections. Partial reversion of pre-transplant immune senescence is observed for some renal transplant patients. In conclusion, to reduce the increasing incidence of morbidity and mortality of chronic kidney disease patients, a better knowledge of uremia-induced immune senescence would help to pave the way to build clinical studies and promote innovative therapeutic approaches. We believe that therapeutic reversion and immune senescence prevention approaches will be part of the management of chronic kidney disease patients in the future.

Anti-Thymocyte Globulin Prophylaxis Induces a Decrease in Naive Th Cells to Inhibit the Onset of Chronic Graft-versus-Host Disease: Results from the Canadian Bone Marrow Transplant Group (CBMTG) 0801 Study

Anti-thymocyte globulin (ATG) is an established approach to decrease chronic GVHD (cGVHD), yet the exact mechanism is uncertain. To better understand the mechanism of action of ATG in preventing cGVHD, we evaluated the day 100 immune reconstitution of known cGVHD cellular biomarkers using patients from the randomized Canadian Bone Marrow Transplant Group (CBMTG) 0801 trial, which demonstrated a significant impact of ATG on cGVHD. In a separate companion biology study, we evaluated the impact of ATG prophylaxis on cGVHD cellular markers at day 100 in 40 CBMTG 0801 patients. Analysis focused on previously identified cGVHD cellular biomarkers, including naive helper T (Th) cells, recent thymic emigrant (RTE) Th cells, CD21^low B cells, CD56^bright NK_reg cells, and T_reg cells ST2, osteopontin, soluble B-cell activating factor (sBAFF), Interleukin-2 receptor alpha (sCD25), T-cell immunoglobulin and mucin domain-3 (TIM-3), matrix metallopeptidase 3, ICAM-1, C-X-C motif chemokine 10 (CXCL10), and soluble aminopeptidase N. The ATG-treated group had a >10-fold decrease in both RTE naive Th and naive Th cells (P < .0001) and a 10-fold increase in CD56^bright NK_reg cells (P < .0001). T_reg cells, conventional Th cells, CD21^low B cells, and all plasma markers were not affected. In the populations most affected by ATG, changes in naive Th cells were associated with the later development of cGVHD. This analysis suggests that ATG primarily impacts on cGVHD through suppression of naive Th cell expansion after transplantation. These associations need to be validated in additional studies.

Long-Term Outcome and Rejection After Allogeneic Uterus Transplantation in Cynomolgus Macaques

Uterus transplantation (UTx) is an option for women with uterine factor infertility to have a child, but is still in the experimental stage. Therefore, allogeneic animal models of UTx are required for resolution of clinical issues. In this study, long-term outcomes were evaluated in four recipients (cases 1-4) after allogeneic UTx in cynomolgus macaques. Immunosuppression with antithymocyte globulin induction and a triple maintenance regimen was used. Postoperative ultrasonography and biopsy of the transplanted uterus and immunoserological examinations were performed. All four recipients survived for >3 months after surgery, but continuous menstruation did not resume, although temporary menstruation occurred (cases 1 and 2). All animals were euthanized due to irreversible rejection and no uterine blood flow (cases 1, 2 and 4) and post-transplant lymphoproliferative disorder (case 3). Donor-specific antibodies against MHC class I and II were detected in cases 1, 2 and 4, but not in case 3. Peripheral lymphocyte counts tended to elevate for CD3⁺, CD20⁺ and NK cells in conjunction with uterine rejection, and all animals had elevated stimulation indexes of mixed lymphocyte reaction after surgery. Establishment of allogeneic UTx in cynomolgus macaque requires further exploration of immunosuppression, but the clinicopathological features of uterine rejection are useful for development of human UTx.

The Efficacy of Rabbit Anti-Thymocyte Globulin for Acute Kidney Transplant Rejection in Patients Using Calcineurin Inhibitor and Mycophenolate Mofetil-Based Immunosuppressive Therapy

Background

T cell depleting antibody therapy with rabbit anti-thymocyte globulin (rATG) is the treatment of choice for glucocorticoid-resistant acute kidney allograft rejection (AR) and is used as first-line therapy in severe AR. Almost all studies investigating the effectiveness of rATG for this indication were conducted at the time when cyclosporine A and azathioprine were the standard of care. Here, the long-term outcome of rATG for AR in patients using the current standard immunosuppressive therapy (i.e., tacrolimus and mycophenolate mofetil) is described.

Material/Methods

Between 2002 to 2012, 108 patients were treated with rATG for AR. Data on kidney function in the year following rATG and long-term outcomes were collected.

Results

Overall survival after rATG was comparable to overall survival of all kidney transplantation patients (P=0.10). Serum creatinine 1 year after rATG was 179 μmol/L (interquartile range (IQR) 136–234 μmol/L) and was comparable to baseline serum creatinine (P=0.22). Early AR showed better allograft survival than late AR (P=0.0007). In addition, 1 year after AR, serum creatinine was lower in early AR (157 mol/L; IQR 131–203) compared to late AR (216 mol/L; IQR 165–269; P<0.05). The Banff grade of rejection, kidney function at the moment of rejection, and reason for rATG (severe or glucocorticoid resistant AR) did not influence the allograft survival.

Conclusions

Treatment of AR with rATG is effective in patients using current standard immunosuppressive therapy, even in patients with poor allograft function. Early identification of AR followed by T cell depleting treatment leads to better allograft outcomes.

Drug-Induced Hematological Cytopenia in Kidney Transplantation and the Challenges It Poses for Kidney Transplant Physicians

Drug-induced hematological cytopenia is common in kidney transplantation. Various cytopenia including leucopenia (neutropenia), thrombocytopenia, and anemia can occur in kidney transplant recipients. Persistent severe leucopenia or neutropenia can lead to opportunistic infections of various etiologies. On the contrary, reducing or stopping immunosuppressive medications in these events can provoke a rejection. Transplant clinicians are often faced with the delicate dilemma of balancing cytopenia and rejection from adjustments of immunosuppressive regimen. Differentials of drug-induced cytopenia are wide. Identification of culprit medication and subsequent modification is also challenging. In this review, we will discuss individual drug implicated in causing cytopenia and correlate it with corresponding literature evidence.

Does Rabbit Antithymocyte Globulin (Thymoglobuline®) Have a Role in Avoiding Delayed Graft Function in the Modern Era of Kidney Transplantation?

Delayed graft function (DGF) increases the risk of graft loss by up to 40%, and recent developments in kidney donation have increased the risk of its occurrence. Lowering the risk of DGF, however, is challenging due to a complicated etiology in which ischemia-reperfusion injury (IRI) leads to acute tubular necrosis. Among various strategies explored, the choice of induction therapy is one consideration. Rabbit antithymocyte globulin (rATG [Thymoglobuline]) has complex immunomodulatory effects that are relevant to DGF. In addition to a rapid and profound T-cell depletion, rATG inhibits leukocyte migration and adhesion. Experimental studies of rATG have demonstrated attenuated IRI-related tissue damage in reperfused tissues, consistent with histological evidence from transplant recipients. Starting rATG intraoperatively instead of postoperatively can improve kidney graft function and reduce the incidence of DGF. rATG is effective in preventing acute rejection in kidney transplant recipients at high immunological risk, supporting delayed calcineurin inhibitor (CNI) introduction which protects the graft from early insults. A reduced rate of DGF has been reported with rATG (started intraoperatively) and delayed CNI therapy compared to IL-2RA induction with immediate CNI in patients at high immunological risk, but not in lower-risk patients. Overall, induction with rATG induction is the preferred choice for supporting delayed introduction of CNI therapy to avoid DGF in high-risk patients but shows no benefit versus IL-2RA in lower-risk individuals. Evidence is growing that intraoperative rATG ameliorates IRI, and it seems reasonable to routinely start rATG before reperfusion.

Individualizing immunosuppression in lung transplantation

Immunosuppression management after lung transplantation continues to evolve, with an increasing number of agents available for use in various combinations allowing for more choice and individualization of immunosuppressive therapy. Therapeutic developments have led to improved outcomes including lower acute rejection rates and improved survival. However, a one size fits all approach for any immunosuppressive strategy may not be best suited to the individual patient and ultimately patient specific factors must be considered when designing the immunosuppressive regimen. Recipient factors including age, race, co-morbidities, immunologic risk, genetic polymorphisms, concomitant and previous pharmacotherapy, and overall immunosuppression burden should be considered. There are several significant drug-drug interactions with select immunosuppressive agents utilized in lung transplant pharmacotherapy that must be considered when choosing and devising a dosing strategy for an individual immunosuppressive agent. Herein, considerations for immunosuppression management in the individual patient will be reviewed.

Anti-thymocyte globulins in kidney transplantation: focus on current indications and long-term immunological side effects

Antithymocyte globulins (ATGs) are part of the immunosuppression arsenal currently used by clinicians to prevent or treat acute rejection in solid organ transplantation. ATG is a mixture of non-specific anti-lymphocyte immunoglobulins targeting not only T cell subsets but also several other immune and non-immune cells, rendering its precise immunoglobulin composition difficult to appreciate or to compare from one preparation to another. Furthermore, several mechanisms of action have been described. Taken together, this probably explains the efficacy and the side effects associated with this drug. Recent data suggest a long-term negative impact on allograft and patient outcomes, pointing out the need to better characterize the potential toxicity and the benefit-risk balance associated to this immunosuppressive therapy within large clinical trials.

Mesenchymal stromal cells for tolerance induction in organ transplantation

The primary challenge in organ transplantation continues to be the need to suppress the host immune system long-term to ensure prolonged allograft survival. Long-term non-specific immunosuppression can, however, result in life-threatening complications. Thus, efforts have been pursued to explore novel strategies that would allow minimization of maintenance immunosuppression, eventually leading to transplant tolerance. In this scenario, bone marrow-derived mesenchymal stromal cells (MSC), given their unique immunomodulatory properties to skew the balance between regulatory and memory T cells, have emerged as potential candidates for cell-based therapy to promote immune tolerance. Here, we review our initial clinical experience with bone marrow-derived MSC in living-donor kidney transplant recipients and provide an overview of the available results of other clinical programs with MSC in kidney and liver transplantation, highlighting hurdles and success of this innovative cell-based therapy.

Benefits of multimodal enhanced recovery pathway in patients undergoing kidney transplantation

BACKGROUND

Use of enhanced recovery after surgery (ERAS) pathways to accelerate functional recovery and reduce length of stay (LOS) has rarely been investigated in kidney transplantation (KTX).

MATERIALS AND METHODS

Consecutive adult isolated KTXs between July 2015 and July 2016 (ERAS, n = 139) were compared with a historical cohort between January 2014 and July 2015 (HISTORIC, n = 95).

RESULTS

Enhanced recovery after surgery recipients were significantly more likely to receive kidneys that were non-local (56.1% vs 4.2%), higher Kidney Donor Profile Index (36-85, 58.4% vs 45.2%; >85, 15.2% vs 10.7%), cold ischemia time ≥30 h (62.4% vs 4.7%), induced with antithymocyte globulin (97.1% vs 87.4%), and to develop delayed graft function (46.4% vs 25.0%). LOS was shorter by 1 day among ERAS (mean 4.59) compared to HISTORIC patients (mean 5.65) predominantly due to a shift in discharges within 3 days (32.4% vs 4.2%); 30-day readmission to the hospital (27.3% vs 27.4%) or emergency room visit (9.4% vs 7.4%) was similar. There was one 30-day death in the ERAS group and none in the HISTORIC group. Return to bowel function and early meal consumption were significantly associated with ERAS, however, with somewhat higher diarrhea and emesis rates.

CONCLUSION

ERAS following KTX correlated with lower LOS without change in readmissions or ER visits despite higher delayed graft function rates.

Antithymocyte globulins in renal transplantation-from lymphocyte depletion to lymphocyte activation: The doubled-edged sword

Compelling data suggest that lymphocyte depletion following T cell depleting therapy may induce prolonged CD4 T cell lymphopenia and trigger lymphocyte activation in some patients. These profound and non-reversible immune changes in T cell pool subsets are the consequence of both impaired thymic renewal and peripheral homeostatic proliferation. Chronic viral challenges by CMV play a major role in these immune alterations. Even when the consequences of CD4 T cell lymphopenia have been now well described, recent studies shed new light on the clinical consequences of immune activation. In this review, we will first focus on the mechanisms involved in T cell pool reconstitution after T cell depletion and further consider the clinical consequences of ATG-induced T cell activation and senescence in renal transplant recipients.

Differential depletion of total T cells and regulatory T cells and prolonged allotransplant survival in CD3Ɛ humanized mice treated with polyclonal anti human thymocyte globulin

Thymoglobulin (ATG) is a polyclonal rabbit antibody against human thymocytes used as a T cell-depleting agent to prevent or treat allotransplant rejection. The aim of the present study was to investigate the effect of low dose ATG treatment exclusively on T cells using a humanized BALB/c human CD3Ɛ transgenic mouse model expressing both human and murine T cell receptors (TCR). Mice received a single intravenous (i.v.) injection of ATG. Blood and peripheral lymphoid organs were obtained after different time points. We found a significant T cell depletion in this mouse model. In addition, regulatory T cells (Tregs) proved to be less sensitive to depletion than the rest of T cells and the Treg:non-Treg ratio was therefore increased. Finally, we also investigated the effect of ATG in a heterotopic allogenic murine model of heart transplantation. Survival and transplant function were significantly prolonged in ATG-treated mice. In conclusion, we showed (a) an immunosuppressive effect of ATG in this humanized mouse model which is exclusively mediated by reactivity against human CD3Ɛ; (b) provided evidence for a relative resistance of Tregs against this regimen; and

Use of polyclonal/monoclonal antibody therapies in transplantation

INTRODUCTION

For over thirty years, antibody (mAb)-based therapies have been a standard component of transplant immunosuppression, and yet much remains to be learned in order for us to truly harness their therapeutic capabilities. Current mAbs used in transplant directly target and destroy graft-destructive immune cells, interrupt cytokine and costimulation-dependent T and B cell activation, and prevent down-stream complement activation. Areas covered: This review summarizes our current approaches to using antibody-based therapies to prevent and treat allograft rejection. It also provides examples of promising novel mAb therapies, and discusses the potential for future mAb development in transplantation. Expert opinion: The broad capability of antibodies, in parallel with our growing ability to synthetically modulate them, offers exciting opportunities to develop better biologic therapeutics. In order to do so, we must further our understanding about the basic biology underlying allograft rejection, and gain better appreciation of how characteristics of therapeutic antibodies affect their efficacy.

Impact of Immune-Modulatory Drugs on Regulatory T Cell

Immunosuppression strategies that selectively inhibit effector T cells while preserving and even enhancing CD4FOXP3 regulatory T cells (Treg) permit immune self-regulation and may allow minimization of immunosuppression and associated toxicities. Many immunosuppressive drugs were developed before the identity and function of Treg were appreciated. A good understanding of the interactions between Treg and immunosuppressive agents will be valuable to the effective design of more tolerable immunosuppression regimens. This review will discuss preclinical and clinical evidence regarding the influence of current and emerging immunosuppressive drugs on Treg homeostasis, stability, and function as a guideline for the selection and development of Treg-friendly immunosuppressive regimens.

[Immunology and immunosuppression in kidney transplantation. ABO and HLA incompatible kidney transplantation]

OBJECTIVES

To perform a state of the art about immunological features in renal transplantation, immunosuppressive drugs and their mechanisms of action and immunologically high risk transplantations such as ABO and HLA-incompatible transplantation.

MATERIAL AND METHODS

An exhaustive systematic review of the scientific literature was performed in the Medline database (http://www.ncbi.nlm.nih.gov) and Embase (http://www.embase.com) using different associations of the following keywords (MESH): "allogenic response; allograft; immunosuppression; ABO incompatible transplantation; donor specific antibodies; HLA incompatible; desensitization; kidney transplantation". Publications obtained were selected based on methodology, language, date of publication (last 10 years) and relevance. Prospective and retrospective studies, in English or French, review articles; meta-analysis and guidelines were selected and analyzed. This search found 4717 articles. After reading titles and abstracts, 141 were included in the text, based on their relevance.

RESULTS

The considerable step in comprehension and knowledge allogeneic response this last few years allowed a better used of immunosuppression and the discover of news immunosuppressive drugs. In the first part of this article, the allogeneic response will be described. The different classes of immunosuppressive drugs will be presented and the actual management of immunosuppression will be discussed. Eventually, the modalities and results of immunologically high-risk transplantations such as ABO and HLA incompatible transplantations will be reported.

CONCLUSIONS

The knowledge and the control of allogeneic response to allogeneic graft allowed the development of renal transplantation.

Incidence and differential characteristics of culture-negative fever following pancreas transplantation with anti-thymocyte globulin induction

BACKGROUND

Limited data are available on the incidence and characteristics of culture-negative fever following pancreas transplantation (PTx) with anti-thymocyte globulin (ATG) induction. Our study aims to better define the features of culture-negative fever, so it can be delineated from infectious fever, hopefully helping clinicians to guide antibiotic therapy in this high-risk patient population.

METHODS

We performed a retrospective cohort study of postoperative fever among 198 consecutive patients undergoing PTx at our center between August 1, 2004 and December 31, 2014. Fever was classified as culture-negative if there was neither a positive culture nor a documented clinical diagnosis of infection.

RESULTS

Fever was identified in 113 patients; 66 were deemed to be infectious, 39 were culture-negative, and 8 were indeterminate. High body mass index of recipient (odds ratio 1.87, 95% confidence interval: 1.15-3.03, P = 0.011) was a significant factor associated with culture-negative fever in multivariate analysis. No patients with culture-negative fever were diagnosed with infiltrates or effusion on chest radiography. In addition, an increase in white blood cell count, C-reactive protein, and serum amylase was less prominent in culture-negative fever. Culture-negative fever developed most frequently at postoperative 7 or 14 days, showing a biphasic curve.

CONCLUSION

Culture-negative fever develops in a substantial proportion of patients early after PTx. The awareness of the possibility and clinical features of post-transplant culture-negative fever might help clinicians to guide antibiotic therapy in this high-risk patient population, especially following ATG induction and early steroid withdrawal.