ATG induction therapy: long-term effects on Th1 but not on Th2 responses

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.

Intensive immunosuppression followed by autologous hematopoietic stem cell transplantation for the treatment of multiple sclerosis

Autologous hematopoietic stem cell transplantation (AHSCT) to treat multiple sclerosis (MS) has mostly been used in devastating cases as the last option to stop further neurological deterioration. However, evidence from several retrospective clinical trials indicates that young, less disabled patients with highly inflammatory active MS are the most likely to benefit from AHSCT, and after moving from high-intensity to nonmyeloablative procedures the tolerability of AHSCT has increased and its associated risk and mortality have declined considerably. Recent meta-analyses and randomized clinical trials show that AHSCT is more effective than currently approved disease-modifying therapies (DMTs), with suppression of disease activity in 70–90% of patients and long-term cessation of disease activity in two-thirds of treated patients. The rationale for AHSCT is to eliminate autoimmunity and achieve immune resetting by intense immunosuppression followed by infusion of autologous hematopoietic stem cells. Similar effects on the immune system have been suggested for cladribine and alemtuzumab treatment and, together with AHSCT, they constitute the induction or immune-reconstitution therapies for MS. Although, further randomized controlled trials of AHSCT for MS are needed, it has become clear that improved patient selection and lower intensity conditioning regimens have reduced AHSCT associated risks and mortality and strengthened the position of AHSCT among other DMTs. Do we have enough experience and scientific support for AHSCT in MS to move from an exclusive treatment for aggressive, treatment-resistant MS and acquire broader indications, similar to other effective DMTs?

Live vaccines after pediatric solid organ transplant: Proceedings of a consensus meeting, 2018

Growing evidence suggests receipt of live-attenuated viral vaccines after solid organ transplant (SOT) has occurred and is safe and needed due to lapses in herd immunity. A 2-day consortium of experts in infectious diseases, transplantation, vaccinology, and immunology was held with the objective to review evidence and create expert recommendations for clinicians when considering live viral vaccines post-SOT. For consideration of VV and MMR post-transplant, evidence exists only for kidney and liver transplant recipients. For MMR vaccine post-SOT, consider vaccination during outbreak or travel to endemic risk areas. Patients who have received antiproliferative agents (eg. mycophenolate mofetil), T cell-depleting agents, or rituximab; or have persistently elevated EBV viral loads, or are in a state of functional tolerance, should be vaccinated with caution and have a more in-depth evaluation to define benefit of vaccination and net state of immune suppression prior to considering vaccination. MMR and/or VV (not combined MMRV) is considered to be safe in patients who are clinically well, are greater than 1 year after liver or kidney transplant and 2 months after acute rejection episode, can be closely monitored, and meet specific criteria of "low-level" immune suppression as defined in the document.

Homozygous HLA-C1 is Associated with Reduced Risk of Relapse after HLA-Matched Transplantation in Patients with Myeloid Leukemia

Natural killer (NK) cells assume graft-versus-leukemia alloreactivity after hematopoietic stem cell transplantation (HSCT) through their inhibitory killer cell immunoglobulin-like receptors (KIRs). KIR2D family members recognize HLA-C alleles with Asn80 (HLA-C1) or Lys80 (HLA-C2). The predominance of HLA-C1 over HLA-C2 and the frequent presence of KIR2DL1 are characteristic of Japanese people. We compared clinical outcomes among homozygous HLA-C1 (HLA-C1/C1) patients and heterozygous HLA-C1/C2 patients who underwent HLA-matched HSCT for hematologic malignancies by assessing the data of 10,638 patients from the Japanese national registry. HLA-C1/C1 recipients had a lower rate of relapse than HLA-C1/C2 recipients after transplantation for acute myelogenous leukemia (AML) (hazard ratio [HR], .79; P = .006) and chronic myelogenous leukemia (CML) (HR, .48; P = .025), but not for acute lymphoblastic leukemia (HR, 1.36), lymphoma (HR, .97), or low-grade myelodysplastic syndrome (HR, 1.40). We then grouped AML and CML patients together and divided them into several subgroups. Advantages of HLA-C1/C1 recipients over HLA-C1/C2 recipients regarding relapse were observed irrespective of donor relation (related: HR, .79, P = .069; unrelated: HR, .77, P = .022), preparative regimen (myeloablative: HR, .79, P = .014; reduced intensity: HR, .73, P = .084), and occurrence of acute graft-versus-host disease (yes: HR, .70, P = .122; no, HR .71, P = .026) or cytomegalovirus reactivation (reactivated: HR .67,P = .054; nonreactivated: HR .71, P = .033); however, these advantages were not observed in recipients with a delay in achieving complete chimerism (HR, 1.06). The advantage of decreasing relapse and extending relapse-free survival of C1/1 over C1/2 KIR-ligand status was most pronounced in T cell-depleted HSCT (HR, .27; P < .001 and HR, .30; P = .002, respectively) and in children age <15 years (HR, .29; P < .001 and HR .31; P < .001, respectively). Our findings represent an important mechanism responsible for the immunity against HLA-C2-negative myeloid leukemia cells after HLA-matched transplantation.

Perioperative effects of high doses of intraoperative thymoglobulin induction in liver transplantation

AIM: To describe our single-centre experience in liver transplantation (LT) with the infusion of high perioperative thymoglobulin doses. The optimal dosage and timing of thymoglobulin^® [antithymocyte globulin (ATG)] administration during LT remains controversial. Cytokine release syndrome, haemolytic anaemia, thrombocytopenia, neutropenia, fever and serum sickness are potential adverse effects associated with ATG infusion.

METHODS: Between December 2009 and December 2010, 16 adult non-randomized patients (ATG group), receiving a liver graft from a deceased donor, received an intraoperative infusion (4-6 h infusion) of thymoglobulin (3 mg/kg, ATG: Thymoglobuline^®). These patients were compared (case control approach) with 16 patients who had a liver transplant without ATG treatment (control group) to evaluate the possible effects of intraoperative ATG infusion. The matching parameters were: Sex, recipient age (± 5 years), LT indication including viral status, MELD score (± 5 points), international normalized ratio and platelet count (as close as possible). The exclusion criteria for both groups included the following: Multi-organ or living donor transplant, immunosuppressive therapy before transplantation, contraindications to the administration of any thymocyte globulin, human immunodeficiency virus seropositivity, thrombocytopenia [platelet < 50000/μL] or leukopenia [white blood cells < 1000/μL]. The perioperative side effects (haemodynamic alterations, core temperature variations, colloids and crystalloids requirements, and surgical time) possibly related to ATG infusion and the thromboelastographic (TEG) evaluation of the ATG effects on coagulation, blood loss and blood product transfusion were analysed during the operation and the first three postoperative days.

RESULTS: Intraoperative ATG administration was associated with longer surgical procedures [560 ± 88 min vs 480 ± 83 min (control group), P = 0.013], an intraoperative core temperature more than 37 °C (50% of ATG patients vs 6.2% of control patients, P = 0.015), major intraoperative blood loss [3953 ± 3126 mL vs 1419 ± 940 mL (control group), P = 0.05], higher red blood cell [2092 ± 1856 mL ATG group vs 472 ± 632 mL (control group), P = 0.02], fresh frozen plasma [671 ± 1125 mL vs 143 ± 349 mL (control group), P = 0.015], and platelet [374 ± 537 mL vs 15.6 ± 62.5 mL (control group), P = 0.017] transfusion, and a higher requirement for catecholamines (0.08 ± 0.07 μg/kg per minutes vs 0.01 ± 0.38 μg/kg per minutes, respectively, in the ATG and control groups) for haemodynamic support. The TEG tracings changed to a straight line during ATG infusion (preanhepatic and anhepatic phases) in 81% of the patients from the ATG group compared to 6.25% from the control group (P < 0.001). Patients from the ATG group compared to controls had higher post-op core temperatures (38 °C ± 1.0 °C vs 37.3 °C ± 0.5 °C; P = 0.02), an increased need of noradrenaline (43.7% vs 6.25%, P = 0.037), received more platelet transfusions (31.5% vs 0%, P = 0.04) and required continuous renal replacement therapy (4 ATG patients vs none in the control group; P = 0.10). ATG infusion was considered the cause of a fatal anaphylactic shock and of a suspected adverse reaction that led to intravascular haemolysis and acute renal failure.

CONCLUSION: The side effects and the coagulation imbalance observed in patients receiving a high dosage of ATG suggest caution in the use of thymoglobulin during LT.

Mycophenolic acid versus azathioprine as primary immunosuppression for kidney transplant recipients

BACKGROUND

Modern immunosuppressive regimens after kidney transplantation usually use a combination of two or three agents of different classes to prevent rejection and maintain graft function. Most frequently, calcineurin-inhibitors (CNI) are combined with corticosteroids and a proliferation-inhibitor, either azathioprine (AZA) or mycophenolic acid (MPA). MPA has largely replaced AZA as a first line agent in primary immunosuppression, as MPA is believed to be of stronger immunosuppressive potency than AZA. However, treatment with MPA is more costly, which calls for a comprehensive assessment of the comparative effects of the two drugs.

OBJECTIVES

This review of randomised controlled trials (RCTs) aimed to look at the benefits and harms of MPA versus AZA in primary immunosuppressive regimens after kidney transplantation. Both agents were compared regarding their efficacy for maintaining graft and patient survival, prevention of acute rejection, maintaining graft function, and their safety, including infections, malignancies and other adverse events. Furthermore, we investigated potential effect modifiers, such as transplantation era and the concomitant immunosuppressive regimen in detail.

SEARCH METHODS

We searched Cochrane Kidney and Transplant's Specialised Register (to 21 September 2015) through contact with the Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

All RCTs about MPA versus AZA in primary immunosuppression after kidney transplantation were included, without restriction on language or publication type.

DATA COLLECTION AND ANALYSIS

Two authors independently determined study eligibility, assessed risk of bias and extracted data from each study. Statistical analyses were performed using the random-effects model and the results were expressed as risk ratio (RR) for dichotomous outcomes and mean difference (MD) for continuous outcomes with 95% confidence intervals (CI).

MAIN RESULTS

We included 23 studies (94 reports) that involved 3301 participants. All studies tested mycophenolate mofetil (MMF), an MPA, and 22 studies reported at least one outcome relevant for this review. Assessment of methodological quality indicated that important information on factors used to judge susceptibility for bias was infrequently and inconsistently reported.MMF treatment reduced the risk for graft loss including death (RR 0.82, 95% CI 0.67 to 1.0) and for death-censored graft loss (RR 0.78, 95% CI 0.62 to 0.99, P < 0.05). No statistically significant difference for MMF versus AZA treatment was found for all-cause mortality (16 studies, 2987 participants: RR 0.95, 95% CI 0.70 to 1.29). The risk for any acute rejection (22 studies, 3301 participants: RR 0.65, 95% CI 0.57 to 0.73, P < 0.01), biopsy-proven acute rejection (12 studies, 2696 participants: RR 0.59, 95% CI 0.52 to 0.68) and antibody-treated acute rejection (15 studies, 2914 participants: RR 0.48, 95% CI 0.36 to 0.65, P < 0.01) were reduced in MMF treated patients. Meta-regression analyses suggested that the magnitude of risk reduction of acute rejection may be dependent on the control rate (relative risk reduction (RRR) 0.34, 95% CI 0.10 to 1.09, P = 0.08), AZA dose (RRR 1.01, 95% CI 1.00 to 1.01, P = 0.10) and the use of cyclosporin A micro-emulsion (RRR 1.27, 95% CI 0.98 to 1.65, P = 0.07). Pooled analyses failed to show a significant and meaningful difference between MMF and AZA in kidney function measures.Data on malignancies and infections were sparse, except for cytomegalovirus (CMV) infections. The risk for CMV viraemia/syndrome (13 studies, 2880 participants: RR 1.06, 95% CI 0.85 to 1.32) was not statistically significantly different between MMF and AZA treated patients, whereas the likelihood of tissue-invasive CMV disease was greater with MMF therapy (7 studies, 1510 participants: RR 1.70, 95% CI 1.10 to 2.61). Adverse event profiles varied: gastrointestinal symptoms were more likely in MMF treated patients and thrombocytopenia and elevated liver enzymes were more common in AZA treatment.

AUTHORS' CONCLUSIONS

MMF was superior to AZA for improvement of graft survival and prevention of acute rejection after kidney transplantation. These benefits must be weighed against potential harms such as tissue-invasive CMV disease. However, assessment of the evidence on safety outcomes was limited due to rare events in the observation periods of the studies (e.g. malignancies) and inconsistent reporting and definitions (e.g. infections, adverse events). Thus, balancing benefits and harms of the two drugs remains a major task of the transplant physician to decide which agent the individual patient should be started on.

Clinical Relevance of Apheretic Graft Composition in Patients With Acute Myeloblastic Leukemia Who Received a Busulfan-Fludarabine-Antithymocyte Globulin Conditioning Regimen for Allogeneic Transplant

OBJECTIVES

Sparse data are available about the effects of apheretic graft composition on the clinical transplant outcome in allotransplanted patients who have hematologic malignant disease. Major obstacles in recent studies have included heterogeneity of patient populations and differences in the conditioning regimens used.

MATERIALS AND METHODS

This prospective study included 50 patients who had acute myeloblastic leukemia and received busulfan-fludarabine-antithymocyte globulin-based conditioning for peripheral allogeneic stem cell transplant. The concentration of CD34+ cells, T-cell subsets, B cells, and natural killer cells in the graft were analyzed by flow cytometry in the donors who were matched for human leukocyte antigen.

RESULTS

In univariate analysis, infusion with a higher dose of natural killer cells (> 1.55 × 106/kg) was associated with improved survival (P = .007 for disease-free survival; P = .024 for overall survival) in patients with acute myeloblastic leukemia. Cox regression models revealed that increased concentration of natural killer cells and CD34+ cells positively affected the clinical outcome of allotransplanted patients (P = .005 for both cell types). According to univariate analysis, these findings were dependent on minimal residual disease and acute graft-versus-host disease. Graft-versus-host disease (acute and chronic forms) was not affected by graft composition.

CONCLUSIONS

Our results suggest that increased concentration of natural killer cells and CD34+ cells in the apheretic product may predict better survival. In contrast, busulfan-fludarabine-antithymocyte globulin-based conditioning eliminates the disadvantages that resulted from the high content of T-cell subsets and B cells, and the course of the transplant and clinical parameters were not affected by the amount of T and B cells.

Effectiveness of fludarabine- and busulfan-based conditioning regimens in patients with acute myeloblastic leukemia: 8-year experience in a single center

OBJECTIVE

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative treatment for acute myeloblastic leukemia (AML). Because the conditioning regimen of busulfan plus cyclophosphamide carries significant risks of toxicity, we evaluated the factors affecting survival after fludarabine replacement instead of cyclophosphamide.

METHODS

The study included 55 patients who underwent allo-HSCT for AML and received busulfan, fludarabine, and antithymocyte globulin (ATG).

RESULTS

Forty-eight patients received a myeloablative regimen; 7 patients received a reduced-intensity conditioning regimen. The neutrophil and platelet engraftment times were 12 days (range 9 to 20) and 12 days (range 7 to 19), respectively. Graft-vs-host disease (GvHD) developed in 10% and 50% of the patients, respectively. Seven patients received donor lymphocyte infusion. Of them, 5 patients developed grade I or II GvHD, one grade IV GvHD. The median follow-up period was 20.6 months. The predicted progression-free survival (PFS) at 1 and 3 years after transplantation was 78% and 74%, respectively. The overall survival (OS) at 1, 3, and 5 years was 76%, 74%, and 62%, respectively. Treatment-related mortality (infection in 1 patient, GvHD in 2 patients) occurred in 3 patients (5.5%). Multivariate analysis revealed that OS and PFS were not influenced by age, dose of busulfan or ATG, or presence of cytomegalovirus antigenemia. Acute GvHD and pretransplantation minimal residual disease positivity negatively affected the transplant outcome. The presence of active disease at the time of transplantation was found as an independent risk factor for AML.

CONCLUSIONS

Busulfan- and fludarabine-based conditioning regimens are effective for AML, and have acceptable toxicity, morbidity, and mortality.

Apoptotic effects of antilymphocyte globulins on human pro-inflammatory CD4+CD28- T-cells

Background

Pro-inflammatory, cytotoxic CD4⁺CD28⁻ T-cells with known defects in apoptosis have been investigated as markers of premature immuno-senescence in various immune-mediated diseases. In this study we evaluated the influence of polyclonal antilymphocyte globulins (ATG-Fresenius, ATG-F) on CD4⁺CD28⁻ T-cells in vivo and in vitro.

Principal Findings

Surface and intracellular three colour fluorescence activated cell sorting analyses of peripheral blood mononuclear cells from 16 consecutive transplant recipients and short-term cell lines were performed. In vivo, peripheral levels of CD3⁺CD4⁺CD28⁻ T-cells decreased from 3.7±7.1% before to 0±0% six hours after ATG-F application (P = 0.043) in 5 ATG-F treated but not in 11 control patients (2.9±2.9% vs. 3.9±3.0%). In vitro, ATG-F induced apoptosis even in CD4⁺CD28⁻ T-cells, which was 4.3-times higher than in CD4⁺CD28⁺ T-cells. ATG-F evoked apoptosis was partially reversed by the broad-spectrum caspase inhibitor benzyloxycarbonyl (Cbz)-Val-Ala-Asp(OMe)-fluoromethylketone (zVAD-fmk) and prednisolon-21-hydrogensuccinate. ATG-F triggered CD25 expression and production of pro-inflammatory cytokines, and induced down-regulation of the type 1 chemokine receptors CXCR-3, CCR-5, CX3CR-1 and the central memory adhesion molecule CD62L predominately in CD4⁺CD28⁻ T-cells.

Conclusion

In summary, in vivo depletion of peripheral CD3⁺CD4⁺CD28⁻ T-cells by ATG-F in transplant recipients was paralleled in vitro by ATG-F induced apoptosis. CD25 expression and chemokine receptor down-regulation in CD4⁺CD28⁻ T-cells only partly explain the underlying mechanism.

The effect of low and ultra-low dosages Thymoglobulin on peripheral T, B and NK cells in kidney transplant recipients

INTRODUCTION

Rabbit Anti-Thymocyte Globulin (r-ATG) is a polyclonal antibody preparation, used to prevent and treat acute rejection episodes after organ transplantation. However, despite more than 40 years of clinical use, the optimal dose of r-ATG is still not defined. To find a better balance between efficacy and infectious complications, we embarked on a controlled study and monitored the effect of low and ultra-low dosages Thymoglobulin (Genzyme) on peripheral T, B, and NK cells.

PATIENTS AND METHODS

Kidney transplant recipients received either 0.5 mg/kg, 1.0 mg/kg or 2.0 mg/kg on the first 3 consecutive days post-transplantation. Thus, total doses were 1.5 mg/kg, 3.0 mg/kg and 6.0 mg/kg. A total of 40 patients were enrolled, including 11 controls. All patients were treated with Prednisolon, Advagraf (Astellas) and Mycophenolate Mofetil (Roche). T (CD3+), B (CD19+) and NK (CD3-CD16+56+) cells were analyzed by flow cytometry. Baseline cell counts were compared to forty age and sex matched healthy persons. Post-transplantation cell counts of the 3 Thymoglobulin groups were compared to the 11 control patients, who received no induction therapy.

RESULTS

Absolute numbers of T, B, and NK cells were comparable in all patients pre-transplantation, but T and B cells were lower than in healthy persons (p=0.007 and p=0.0003, Mann Whitney test). In the first week, T cells and NK cells were significantly lower in all Thymoglobulin groups compared to controls. B cells were not affected. One month after Thymoglobulin NK cells had returned to control numbers in all groups, while T cells had already recovered to control counts in the 1.5 mg/kg group. During follow-up, T cells in the 3.0mg/kg group also returned to control values, but at one year the patients in the 6.0 mg/kg group still had significantly lower T cells (p=0.03). Patient and graft survival, rejection and infection incidence and renal function did not differ between groups.

CONCLUSION

Patients with end stage renal disease have significantly lower peripheral T and B cell counts than healthy persons. (Ultra-) low Thymoglobulin schedules deplete peripheral lymphocytes in a dose dependent way. Knowledge of the duration of this depletion contributes to finding the optimal immunosuppressive strategy for kidney transplant recipients.

The effect of rabbit anti-thymocyte globulin induction therapy on regulatory T cells in kidney transplant patients

BACKGROUND

Prevention of alloreactivity by rabbit anti-thymocyte globulins (rATG) may not only result from immunodepletion but also from the induction of T cells that control allogeneic immune responses. In the present prospective and controlled study, we investigated the effect of rATG on the frequency, function and phenotype of peripheral immunoregulatory CD4+ T cells in kidney transplant (KTx) patients.

METHODS

After transplantation, 16 patients received ATG-induction therapy and triple therapy consisting of tacrolimus, MMF and steroids. The control group (n = 18) received triple therapy only. By flow cytometry, T cells were analysed for CD25, FoxP3, CD127, CD45RO and CCR7. To study their suppressive capacities, CD25bright T cells were co-cultured with CD25(-/dim) effector T cells (Teff) in mixed lymphocyte reactions (MLR), stimulated with donor and third party (3P) antigens.

RESULTS

Pre-transplant levels of FoxP3+CD127(-/low) T cells were 6% of CD4+ T cells. One week post-ATG treatment, no measurable numbers of regulatory T cells were present (P < 0.01). After 4 weeks, the cell numbers of CD4+FoxP3+CD127(-/low) T cells slowly reappeared and thereafter remained low (P < 0.01). At 14 weeks, a significant shift towards the CD45RO+CCR7+ (central memory) phenotype within CD4+FoxP3+ T cells was observed (P < 0.01). At 26 weeks, the proliferative alloresponses of the PBMC and CD25(-/dim) Teff profoundly decreased compared to pre-transplant (P = 0.01 and P = 0.02 respectively), while the regulatory capacity of the CD25bright T cells, of which 90% consisted of FoxP3+CD127(-/low) T cells, remained unaffected. The CD25bright T cells suppressed the anti-donor (94%) and 3P responses (93%).

CONCLUSION

Our findings show that rATG therapy does not spare peripheral immunoregulatory T cells in vivo, but after regeneration preserves their suppressive activity.

Effect of prophylaxis with low-dose anti-thymocyte globulin on prevention of acute kidney allograft rejection

INTRODUCTION

During kidney transplantation, the first contact between the recipient's immune system and the donor organ takes place immediately following the arterial anastomosis. The aim of this study was to evaluate the efficacy of a single, low-dose anti-thymocyte globulin (ATG) prophylaxis in the reduction of early acute rejection in renal allograft recipients.

METHODS

In a randomized, controlled clinical trial, we studied the rate of acute rejection within the first month of kidney transplantation in patients who had received their transplant at a single center between the years 2004 and 2007. The patients were divided into 2 groups: group 1 (n = 37) received cyclosporine, mycophenolate mofetil or azathioprine, and prednisolone; group 2 (n = 31) received the above-mentioned agents plus a single ATG bolus (Thymoglobulin; SangStat, Lyon, France; 4-5 mg/kg) the night before the transplantation ( approximately 12 hours before the operation). Blood urea and serum creatinine levels were measured regularly in the posttransplantation period. Acute allograft rejection was justified clinically and/or pathologically. Statistical analysis was performed by SPSS 13.0 using Student t test and Fisher exact test. A P value < or = .05 was considered to indicate statistical significance.

RESULTS

There were no significant differences regarding the age and gender ratio between the 2 groups. Acute allograft rejection was found in 32.4% (n = 12) of group 1 patients, and was reduced to 12.9% (n = 4) in group 2 (P = .05). Hence, the first-month acute rejection episodes decreased by approximately 60% with ATG prophylaxis in renal transplant recipients.

CONCLUSION

Prophylactic administration of a single and low-dose ATG the night before kidney transplantation could reduce the risk of acute allograft rejection in renal transplant recipients. However, further studies with a greater number of patients should be conducted to confirm these results.

One center's experience with antithymocyte globulin treatment for acute rejection in renal transplantation

Antithymocyte globulin (ATG) is a polyclonal antibody used in renal transplantation for prevention and treatment of acute rejection. In this study we have presented the outcomes of 23 cases treated with ATG due to steroid-resistant acute rejection episodes in 17 male and 6 female recipients. Sixteen transplantations were performed from cadaver donors and the other 7 from living-related donors. The mean recipient age was 31.9 +/- 9 years and the mean donor age was 56.3 +/- 10.8 years. ATG treatment was administered in doses of 3-5 mg/kg/d for 10 or 14 days. All patients received the same premedication before the ATG treatment; we did not encounter any ATG-related side effects. ATG doses were adjusted according to the T-lymphocyte levels. All recipients were followed up for infectious complications, for graft function, and for immunologic parameters of CD3 levels, CD4 levels, CD3/CD4 ratios, lymphocyte, and polymorphonuclear leukocyte numbers. According to the Banff criteria introduced in 1997, 4 patients displayed humoral rejection: 3 had type 3; 5 had type 2; and 11 had type 1 acute rejection episodes. Nine patients developed infectious complication during the follow-up. Three had pulmonary aspergillosis; 2 had cytomegalovirus infection; and 4 had bacterial infections. One patient who experienced aspergillosis died with a functioning graft, and the remaining 8 patients were treated successfully. Graft function improved in 19 (83%) cases. The other 4 patients returned to hemodialysis. Mean creatinine levels decreased from 4 +/- 1.7 to 2.1 +/- 0.2 mg/dL. We did not observe any relationship between the immunologic parameters and infectious complications. In conclusion, although ATG is a powerful drug to treat steroid-resistant acute rejection episodes, there was no precise way to monitor the intensity of immunosuppression to prevent infectious complications.

Single bolus antithymocyte globulin versus basiliximab induction in kidney transplantation with cyclosporine triple immunosuppression: efficacy and safety

BACKGROUND

The aim of this prospective randomized study was to examine the effect of induction immunosuppression and low initial cyclosporine (CsA) on the onset of graft function and its long-term consequences.

METHODS

During 1999-2001, 155 patients were randomized to single 9 mg/kg dose antithymocyte globulin (ATG)-Fresenius (group A) or two 20-mg doses of basiliximab (group B) with reduced dose CsA or conventional CsA triple therapy without induction (group C).

RESULTS

Delayed function (DGF) was lower in group A than in groups B or C (5.7% vs. 24.1% and 15.9%, P<0.025) and need of dialysis was less in groups A and B compared to C (10.3 and 10.4 vs. 20.0 days, P<0.05). Acute rejections occurred in 11.3%, 12.1% and 20.5%, and the mean (median) time to rejection was 16 (13), 97 (46) and 101 (35) days in groups A, B, and C, respectively (P<0.005). One-and 5-year graft survivals (GS) were 98.1% and 90.6% (group A), 96.6% and 96.6% (group B), and 93.2% and 84.1% (group C). Five-year GS was significantly better in group B than in group C (P<0.05). The death censored 5-year GS in groups A, B, and C were 94.3%, 96.6%, and 90.0% (P=NS). Single high-dose ATG induction was associated with hemodynamic and pulmonary disturbances without, however, serious or long-term consequences.

CONCLUSIONS

ATG induction significantly reduced DGF. Both induction regimens together with low initial CsA led to significantly less posttransplant dialysis and excellent survival. The high dose ATG was associated with significant hemodynamic and pulmonary side effects during drug infusion.

Hepatotoxicity induced by horse ATG and reversed by rabbit ATG: a case report

BACKGROUND

The use of antilymphocyte agents has improved patient and graft survival in hematopoietic stem cell and solid organ transplantation but has been associated with the development of short-term toxicities as well as long-term complications.

CASE PRESENTATION

We report a young female with Fanconi anemia who received antithymocyte globulin as part of the conditioning regimen prior to her planned allogeneic hematopoietic stem cell transplant at King Faisal Specialist Hospital and Research Centre in Riyadh. She developed sudden and severe hepatotoxicity after receiving the first dose of horse antithymocyte globulin, manifested by marked elevation of serum transaminases and mild elevation of serum bilirubin level. Immediately after withdrawal of the offending agent and shifting to the rabbit form of antithymocyte globulin, the gross liver dysfunction started to subside and the hepatic profile results returned to the pre-transplant levels few weeks later. The patient had her allogeneic hematopoietic stem cell transplant as planned without any further hepatic complications. After having a successful allograft, she was discharged from the stem cell transplant unit. During her follow up at the outpatient clinic, the patient remained very well and no major complication was encountered.

CONCLUSION

Hepatotoxicity related to the utilization of antithymocyte globulin varies considerably in severity and may be transient or long standing. There may be individual or population based susceptibilities to the development of side effects and these adverse reactions may also vary with the choice of the agent used. Encountering adverse effects with one type of antithymocyte agents should not discourage clinicians from shifting to another type in situations where continuation of the drug is vital.

Antithymocyte globulins suppress dendritic cell function by multiple mechanisms

BACKGROUND

The polyclonal rabbit antithymocyte and anti-T-cell immunoglobulins (ATGs) Thymoglobulin (TG) and ATG-Fresenius S (ATG-F) have been widely used for the prevention and therapy of allograft rejection and graft versus host disease in transplantation. Although immunosuppressive mechanisms of ATGs on T cells are well studied, less is known about their impact on dendritic cells (DCs).

METHODS

Effects of TG and ATG-F on immune functions and signaling pathways of human monocyte-derived DCs were determined by flow cytometry, enzyme-linked immunosorbent assay, Western blot, apoptosis assays, endocytosis assays, and T cell stimulation assays.

RESULTS

TG and ATG-F bind rapidly and with high affinity to CD11c, CD80, CD86, CD40, CD36, CD38, CD206, and human leukocyte antigen-DR on DCs. TG and, to a lesser extent, ATG-F induce apoptosis in immature and mature DCs. Macropinocytotic and receptor-mediated endocytotic antigen uptake in immature DCs is inhibited by TG and ATG-F due to their binding of the C-type lectins CD206 and CD209. TG and ATG-F induce activation of the mitogen-activated protein kinases ERK1/2 and p38 that contributes to the induction of apoptosis. TG and ATG-F also induce cytoplasmic-nuclear translocation of the NF-kappaB/Rel transcription factors RelB, RelA, p50, and p52. Production of interleukin-12p70 in mature DCs is suppressed by TG and ATG-F. TG and ATG-F reduce the capacity of mature DCs to stimulate allogeneic and autologous T cells.

CONCLUSIONS

ATGs interfere with basic DC functions, suggesting that DCs are relevant targets for the immunosuppressive action of ATGs in transplantation.

Long-term results (10 years) of a prospective trial comparing Lo-tact-1 monoclonal antibody and anti-thymocyte globulin induction therapy in kidney transplantation

To evaluate long-term patient and graft survival, and the incidence of acute and chronic rejection, infectious diseases and malignancies following induction therapy with a rat monoclonal interleukin 2 receptor antibody, Lo-Tact-1, or anti-thymocyte globulin (ATG). Forty first-time kidney transplant patients were prospectively randomized to two groups between May 1990 and June 1991. Twenty recipients were treated with Lo-Tact-1 (group 1) and the other 20, with ATG (group 2) during the first 14 days of the transplantation protocol. All patients were treated with azathioprine, steroids and cyclosporin A. Data were collected over 10 years. Median age was 42.1 years in group 1 and 39.3 years in group 2. Six recipients died during the 10 years of follow-up. All had functioning grafts. Death-censored graft survival was 35% in group 1 and 45% in group 2 after 10 years (P = NS). The number of acute rejection was similar in the two groups. Chronic allograft rejection was significantly more frequent in group 2 (n = 9) than in group 1 (n = 3), P < 0.05. Viral and bacterial infections were more frequent in group 2 than in group 1 (respectively 8 vs. 2 and 16 vs. 10, P < 0.05). Three patients had cancer. Although both Lo-tact-1 and ATG effectively prevented acute renal rejection, fewer bacterial and viral infections and cases of chronic allograft rejection were observed in Lo-tact-1-treated patients after 10 years of follow-up, demonstrating the potential value of this treatment for kidney transplantation.

Development of a secondary autoimmune disorder after hematopoietic stem cell transplantation for autoimmune diseases: role of conditioning regimen used

Patients undergoing autologous hematopoietic stem cell transplantation (auto-HSCT) for autoimmune disease may have an added propensity to develop a second autoimmune disorder, given the genetic predisposition to autoimmunity. Therefore, we undertook a retrospective analysis of all patients who have undergone auto-HSCT for an autoimmune disease in our institution to determine the occurrence of a second autoimmune disorder and possible risk factors. In all, 155 patients underwent auto-HSCT for various autoimmune diseases; of those patients, 6 manifested a distinct secondary autoimmune disease at a median of 8.5 months (range, 2-30 months) after auto-HSCT. There were 2 patients with systemic lupus erythematosus, conditioned with a regimen containing antithymocyte globulin (ATG), who developed factor VIII inhibitors with severe bleeding. There were 4 patients (2 with multiple sclerosis, one each with lupus and systemic sclerosis) who received an alemtuzumab-containing conditioning regimen who developed autoimmune cytopenias. Among the 155 patients, the frequency of secondary autoimmune complications was 16.0% with alemtuzumab (4/25), 1.9% for ATG (2/102), and 0% for conditioning regimens without lympho-depleting antibodies (0/28)-a difference that was found to be significantly higher with alemtuzumab exposure (P = .011). In contrast, sex, type of ATG used, and CD34-selection of peripheral blood stem cells were not found to be significantly associated with development of a secondary autoimmune disorder.

Comparison of two dosages of thymoglobulin used as a short-course for induction in kidney transplantation

Thymoglobulin is used effectively as an induction agent in kidney transplantation, but the optimal dose is not well established. We evaluated the degree and durability of T-cell clearances with two different thymoglobulin regimens in adult kidney transplant recipients (KTR). Seven KTR received a 3-day thymoglobulin-based induction of 1.0 mg/kg/day while nine received 1.5 mg/kg/day, in addition to maintenance immunosuppression. Lymphocyte subsets were monitored for 6 months. Renal function, infections and malignancies were monitored for 24 months. T-cell subsets were significantly lower by day 30 with the thymoglobulin 1.5 mg/kg/day regimen when compared with the 1.0 mg/kg/day regimen; this trend was sustained at 6-month (CD3(+): 438 +/- 254 vs. 1001 +/- 532 cells/mm(3), P = 0.016). Renal function between the two groups was not significantly different at 6- and 24-months post-transplant. One case of BK Virus viremia in the 1.5 mg/kg/day thymoglobulin group was detected. No acute rejection episodes, cytomegalovirus infections, or malignancies were noted in either group. Thymoglobulin induction was efficacious in both groups, but with a significantly sustained T-cell clearance in the 1.5 mg/kg/day regimen. A more profound T-cell clearance within the first 6 months postinduction therapy may translate into a decreased risk of immunological injury and improved long-term outcome after kidney transplantation.

Post-transplant sCD30 and neopterin as predictors of chronic allograft nephropathy: impact of different immunosuppressive regimens

Immunological monitoring for chronic allograft nephropathy (CAN) is of great potential interest. We assessed serum soluble CD30 (sCD30) together with in vitro Th2-type responses (IL-4, IL-10, CD4 helper activity) and neopterin in a prospective study of 84 renal transplant recipients with 2-year follow-up. Patients were randomized to CsA/Aza, CsA/MMF and Tacr/Aza, respectively, to analyze the effect of immunosuppression on posttransplant sCD30 and neopterin. ATG induction and acute rejections did not alter sCD30 levels whereas CMV disease was associated with transient upregulation of sCD30 (p = 0.003 at 4 months) and sustained upregulation of neopterin (corrected for graft function (Neo/CR) p = 0.005 at 2 years). Tacr versus CsA treatment proved to be an independent variable associated with downregulation of 1-year sCD30, which was positively related to Neo/CR (p = 0.007 and 0.01, respectively; logistic regression). Importantly, increased 1-year sCD30 and Neo/CR were associated with decreased glomerular filtration rate at 2 years (p = 0.02 and p < 0.0005, respectively) and evidence of CAN (p < 0.0005). High 1-year sCD30 could not be attributed to enhanced Th2-type responses and was not associated with HLA antibody formation. Our data suggest that elevated sCD30 and neopterin predict graft deterioration by CAN. Tacr effectively downregulates these responses and might be of advantage in patients with elevated sCD30 or neopterin.