Transplant Candidates of 70+ Years Have Superior Survival If Receiving Pre-Emptively a Living Donor Kidney

Background: The number of kidney transplant recipients over 70 years of age is increasing but detailed data on patient and graft survival in the modern era of immune suppression are few. Methods: A single-center cohort of patients of 70 years and older (n = 349) at time of kidney transplantation from 2010-2020 were followed until January 2023. Results: The median age was 73 years with a median follow-up of 4.3 years. Fifty percent of recipients of a living donor kidney (LDK, n = 143) received their graft pre-emptively. Cumulative death-censored graft survival was excellent in the LDK group and reached 98% at 5 years vs. 85% in the deceased donor kidney (DDK) group. Primary non-function (38%) and rejection (43%) were the major causes of graft loss in the first year after DDK transplantation. Rejection-related graft loss was 4.6% during follow-up. Median recipient survival was superior in the subgroup of pre-emptively transplanted LDK patients compared to non-pre-emptively LDK transplanted patients (11.1 versus 6.2 years). Non-pre-emptively transplanted patients had a significantly increased incidence of infection (HR 3.81, 1.46-9.96) and cardiovascular-related causes of death (HR 3.35, 1.16-9.71). Pre-emptive transplantation was also associated with a significantly improved graft survival in the DDK recipients but this result was confounded by significantly better HLA matching and younger donor age in this group. Conclusions: Pre-emptive LDK transplantation in patients of 70 years or older confers superior graft and recipient survival.

The role of interleukin-21 in COVID-19 vaccine-induced B cell-mediated immune responses in patients with kidney disease and kidney transplant recipients

T-cell-mediated help to B cells is required for the development of humoral responses, in which the cytokine interleukin (IL)-21 is key. Here, we studied the mRNA-1273 vaccine-induced SARS-CoV-2-specific memory T-cell IL-21 response, memory B cell response, and immunoglobulin (Ig)G antibody levels in peripheral blood at 28 days after the second vaccination by ELISpot and the fluorescent bead-based multiplex immunoassay, respectively. We included 40 patients with chronic kidney disease (CKD), 34 patients on dialysis, 63 kidney transplant recipients (KTR), and 47 controls. We found that KTR, but not patients with CKD and those receiving dialysis, showed a significantly lower number of SARS-CoV-2-specific IL-21 producing T cells than controls (P < .001). KTR and patients with CKD showed lower numbers of SARS-CoV-2-specific IgG-producing memory B cells when compared with controls (P < .001 and P = .01, respectively). The T-cell IL-21 response was positively associated with the SARS-CoV-2-specific B cell response and the SARS-CoV-2 spike S1-specific IgG antibody levels (both Pearson r = 0.5; P < .001). In addition, SARS-CoV-2-specific B cell responses were shown to be IL-21 dependent. Taken together, we show that IL-21 signaling is important in eliciting robust B cell-mediated immune responses in patients with kidney disease and KTR.

Current Perspectives on the Management of Herpesvirus Infections in Solid Organ Transplant Recipients

Solid organ transplant recipients (SOTRs) are at high risk of human herpesvirus (HHV)-related morbidity and mortality due to the use of immunosuppressive therapy. We aim to increase awareness and understanding of HHV disease burden in SOTRs by providing an overview of current prevention and management strategies as described in the literature and guidelines. We discuss challenges in both prevention and treatment as well as future perspectives.

Increasing Kidney-Exchange Options Within the Existing Living Donor Pool With CIAT: A Pilot Implementation Study

Computerized integration of alternative transplantation programs (CIAT) is a kidney-exchange program that allows AB0- and/or HLA-incompatible allocation to difficult-to-match patients, thereby increasing their chances. Altruistic donors make this available for waiting list patients as well. Strict criteria were defined for selected highly-immunized (sHI) and long waiting (LW) candidates. For LW patients AB0i allocation was allowed. sHI patients were given priority and AB0i and/or CDC cross-match negative HLAi allocations were allowed. A local pilot was established between 2017 and 2022. CIAT results were assessed against all other transplant programs available. In the period studied there were 131 incompatible couples; CIAT transplanted the highest number of couples (35%), compared to the other programs. There were 55 sHI patients; CIAT transplanted as many sHI patients as the Acceptable Mismatch program (18%); Other programs contributed less. There were 69 LW patients; 53% received deceased donor transplantations, 20% were transplanted via CIAT. In total, 72 CIAT transplants were performed: 66 compatible, 5 AB0i and 1 both AB0i and HLAi. CIAT increased opportunities for difficult-to-match patients, not by increasing pool size, but through prioritization and allowing AB0i and "low risk" HLAi allocation. CIAT is a powerful addition to the limited number of programs available for difficult-to-match patients.

Th1-dominant cytokine responses in kidney patients after COVID-19 vaccination are associated with poor humoral responses

Cytokines are regulators of the immune response against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). However, the contribution of cytokine-secreting CD4⁺ and CD8⁺ memory T cells to the SARS-CoV-2-specific humoral immune response in immunocompromised kidney patients is unknown. Here, we profiled 12 cytokines after stimulation of whole blood obtained 28 days post second 100 μg mRNA-1273 vaccination with peptides covering the SARS-CoV-2 spike (S)-protein from patients with chronic kidney disease (CKD) stage 4/5, on dialysis, kidney transplant recipients (KTR), and healthy controls. Unsupervised hierarchical clustering analysis revealed two distinct vaccine-induced cytokine profiles. The first profile was characterized by high levels of T-helper (Th)₁ (IL-2, TNF-α, and IFN-γ) and Th₂ (IL-4, IL-5, IL-13) cytokines, and low levels of Th₁₇ (IL-17A, IL-22) and Th₉ (IL-9) cytokines. This cluster was dominated by patients with CKD, on dialysis, and healthy controls. In contrast, the second cytokine profile contained predominantly KTRs producing mainly Th₁ cytokines upon re-stimulation, with lower levels or absence of Th₂, Th₁₇, and Th₉ cytokines. Multivariate analyses indicated that a balanced memory T cell response with the production of Th₁ and Th₂ cytokines was associated with high levels of S1-specific binding and neutralizing antibodies mainly at 6 months after second vaccination. In conclusion, seroconversion is associated with the balanced production of cytokines by memory T cells. This emphasizes the importance of measuring multiple T cell cytokines to understand their influence on seroconversion and potentially gain more information about the protection induced by vaccine-induced memory T cells.

Alternative strategies to increase the immunogenicity of COVID-19 vaccines in kidney transplant recipients not responding to two or three doses of an mRNA vaccine (RECOVAC): a randomised clinical trial

BACKGROUND

An urgent need exists to improve the suboptimal COVID-19 vaccine response in kidney transplant recipients (KTRs). We aimed to compare three alternative strategies with a control single dose mRNA-1273 vaccination: a double vaccine dose, heterologous vaccination, and temporary discontinuation of mycophenolate mofetil or mycophenolic acid.

METHODS

This open-label randomised trial, done in four university medical centres in the Netherlands, enrolled KTRs without seroconversion after two or three doses of an mRNA vaccine. Between Oct 20, 2021, and Feb 2, 2022, 230 KTRs were randomly assigned block-wise per centre by a web-based system in a 1:1:1 manner to receive 100 μg mRNA-1273, 2 × 100 μg mRNA-1273, or Ad26.COV2-S vaccination. In addition, 103 KTRs receiving 100 μg mRNA-1273, were randomly assigned 1:1 to continue (mycophenolate mofetil+) or discontinue (mycophenolate mofetil-) mycophenolate mofetil or mycophenolic acid treatment for 2 weeks. The primary outcome was the percentage of participants with a spike protein (S1)-specific IgG concentration of at least 10 binding antibody units per mL at 28 days after vaccination, assessed in all participants who had a baseline measurement and who completed day 28 after vaccination without SARS-CoV-2 infection. Safety was assessed as a secondary outcome in all vaccinated patients by incidence of solicited adverse events, acute rejection or other serious adverse events. This trial is registered with ClinicalTrials.gov, NCT05030974 and is closed.

FINDINGS

Between April 23, 2021, and July 2, 2021, of 12 158 invited Dutch KTRs, 3828 with a functioning kidney transplant participated in a national survey for antibody measurement after COVID-19 vaccination. Of these patients, 1311 did not seroconvert after their second vaccination and another 761 not even after a third. From these seronegative patients, 345 agreed to participate in our repeated vaccination study. Vaccination with 2 × mRNA-1273 or Ad26.COV2-S was not superior to single mRNA-1273, with seroresponse rates of 49 (68%) of 72 (95% CI 56-79), 46 (63%) of 73 (51-74), and 50 (68%) of 73 (57-79), respectively. The difference with single mRNA-1273 was -0·4% (-16 to 15; p=0·96) for 2 × mRNA-1273 and -6% (-21 to 10; p=0·49) for Ad26.COV2-S. Mycophenolate mofetil- was also not superior to mycophenolate mofetil+, with seroresponse rates of 37 (80%) of 46 (66-91) and 31 (67%) of 46 (52-80), and a difference of 13% (-5 to 31; p=0·15). Local adverse events were more frequent after a single and double dose of mRNA-1273 than after Ad26.COV2-S (65 [92%] of 71, 67 [92%] of 73, and 38 [50%] of 76, respectively; p<0·0001). No acute rejection occurred. There were no serious adverse events related to vaccination.

INTERPRETATION

Repeated vaccination increases SARS-CoV-2-specific antibodies in KTRs, without further enhancement by use of a higher dose, a heterologous vaccine, or 2 weeks discontinuation of mycophenolate mofetil or mycophenolic acid. To achieve a stronger response, possibly required to neutralise new virus variants, repeated booster vaccination is needed.

FUNDING

The Netherlands Organization for Health Research and Development and the Dutch Kidney Foundation.

Antibody and T-Cell Responses 6 Months After Coronavirus Disease 2019 Messenger RNA-1273 Vaccination in Patients With Chronic Kidney Disease, on Dialysis, or Living With a Kidney Transplant

BACKGROUND

The immune response to COVID-19 vaccination is inferior in kidney transplant recipients (KTRs) and to a lesser extent in patients on dialysis or with chronic kidney disease (CKD). We assessed the immune response 6 months after mRNA-1273 vaccination in kidney patients and compared this to controls.

METHODS

A total of 152 participants with CKD stages G4/5 (eGFR <30 mL/min/1.73 m2), 145 participants on dialysis, 267 KTRs, and 181 controls were included. SARS-CoV-2 Spike S1 specific IgG antibodies were measured using fluorescent bead-based multiplex-immunoassay, neutralizing antibodies to ancestral, Delta, and Omicron (BA.1) variants by plaque reduction, and T-cell responses by interferon-γ release assay.

RESULTS

At 6 months after vaccination, S1-specific antibodies were detected in 100% of controls, 98.7% of CKD G4/5 patients, 95.1% of dialysis patients, and 56.6% of KTRs. These figures were comparable to the response rates at 28 days, but antibody levels waned significantly. Neutralization of the ancestral and Delta variants was detected in most participants, whereas neutralization of Omicron was mostly absent. S-specific T-cell responses were detected at 6 months in 75.0% of controls, 69.4% of CKD G4/5 patients, 52.6% of dialysis patients, and 12.9% of KTRs. T-cell responses at 6 months were significantly lower than responses at 28 days.

CONCLUSIONS

Although seropositivity rates at 6 months were comparable to rates at 28 days after vaccination, significantly decreased antibody levels and T-cell responses were observed. The combination of low antibody levels, reduced T-cell responses, and absent neutralization of the newly emerging variants indicates the need for additional boosts or alternative vaccination strategies in KTRs.

CLINICAL TRIALS REGISTRATION

NCT04741386.

Clinical Characteristics and Outcomes of Immunocompromised Patients With Coronavirus Disease 2019 Caused by the Omicron Variant: A Prospective, Observational Study

BACKGROUND

Illness after infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant is less severe compared with previous variants. Data on the disease burden in immunocompromised patients are lacking. We investigated the clinical characteristics and outcomes of immunocompromised patients with coronavirus disease 2019 (COVID-19) caused by Omicron.

METHODS

Organ transplant recipients, patients on anti-CD20 therapy, and allogenic hematopoietic stem cell transplantation recipients infected with the Omicron variant were included. Characteristics of consenting patients were collected and patients were contacted regularly until symptom resolution. To identify possible risk factors for hospitalization, a univariate logistic analysis was performed.

RESULTS

114 consecutive immunocompromised patients were enrolled. Eighty-nine percent had previously received 3 mRNA vaccinations. While only 1 patient died, 23 (20%) were hospitalized for a median of 11 days. A low SARS-CoV-2 immunoglobulin G (IgG) antibody response (<300 BAU [binding antibody units]/mL) at diagnosis, being older, being a lung transplant recipient, having more comorbidities, and having a higher frailty score were associated with hospital admission (all P < .01). At the end of follow-up, 25% had still not fully recovered. Of the 23 hospitalized patients, 70% had a negative and 92% had a low IgG (<300 BAU/mL) antibody response at admission. Sotrovimab was administered to 17 of these patients, and 1 died.

CONCLUSIONS

While the mortality in immunocompromised patients infected with Omicron was low, hospital admission was frequent and the duration of symptoms often prolonged. In addition to vaccination, other interventions are needed to limit the morbidity from COVID-19 in immunocompromised patients.

Boosting the VZV-Specific Memory B and T Cell Response to Prevent Herpes Zoster After Kidney Transplantation

Background

Solid organ transplant recipients are at high risk to develop (complicated) herpes zoster (HZ). Booster vaccination could prevent HZ. However, end-stage renal disease (ESRD) patients show poor immunological responses to vaccinations. We studied the effect of a live attenuated VZV booster vaccine on VZV-specific B and T cell memory responses in ESRD patients and healthy controls. NL28557.000.09, www.toetsingonline.nl

Methods

VZV-seropositive patients, aged ≥50 years, awaiting kidney transplantation, were vaccinated with Zostavax^®. Gender and age-matched VZV-seropositive potential living kidney donors were included as controls. VZV-specific IgG titers were measured before, at 1, 3 and 12 months post-vaccination. VZV-specific B and T cell responses before, at 3 months and 1 year after vaccination were analysed by flow-cytometry and Elispot, respectively. Occurrence of HZ was assessed at 5 years post-vaccination.

Results

26 patients and 27 donors were included. Median VZV-specific IgG titers were significantly higher at all time-points post-vaccination in patients (mo 1: 3104 IU/ml [1967-3825], p<0.0001; mo 3: 2659 [1615-3156], p=0.0002; mo 12: 1988 [1104-2989], p=0.01 vs. pre: 1397 [613-2248]) and in donors (mo 1: 2981 [2126-3827], p<0.0001; mo 3: 2442 [2014-3311], p<0.0001; mo 12: 1788 [1368-2460], p=0.0005 vs. pre: 1034 [901-1744]. The patients’ IgG titers were comparable to the donors’ at all time-points. The ratio VZV-specific B cells of total IgG producing memory B cells had increased 3 months post-vaccination in patients (0.85 [0.65-1.34] vs. pre: 0.56 [0.35-0.81], p=0.003) and donors (0.85 [0.63-1.06] vs. pre: 0.53 [0.36-0.79], p<0.0001) and remained stable thereafter in donors. One year post-vaccination, the percentage of CD4+ central memory cells had increased in both patients (0.29 [0.08-0.38] vs. 0.12 [0.05-0.29], p=0.005) and donors (0.12 [0.03-0.37] vs. 0.09 [0.01-0.20], p=0.002) and CD4+ effector memory cells had increased in donors (0.07 [0.02-0.14] vs. 0.04 [0.01-0.12], p=0.007). Only 1 patient experienced HZ, which was non-complicated.

Conclusion

VZV booster vaccination increases VZV-specific IgG titers and percentage VZV-specific memory T-cells for at least 1 year both in ESRD patients and healthy controls. VZV-specific memory B cells significantly increased in patients up to 3 months after vaccination. Prophylactic VZV booster vaccination prior to transplantation could reduce HZ incidence and severity after transplantation.

Alemtuzumab as Second-Line Treatment for Late Antibody-Mediated Rejection of Transplanted Kidneys

Whether the anti-CD52 monoclonal antibody alemtuzumab can be an effective treatment option for late antibody-mediated rejection (ABMR) is not known. In a single-center pilot study, 12 patients with late ABMR were given 30 mg subcutaneous alemtuzumab.Median time from transplantation to biopsy was 22 months with 10 of 12 recipients fulfilling criteria for the histologic diagnosis chronic-active ABMR. The estimated glomerular filtration rate (eGFR) loss before diagnosis was 1.2 mL/min/mo with graft loss (eGFR <15 mL/min) expected to occur within 2 years in 11 of 12 cases. All recipients showed no or an inadequate response to initial treatment with steroids and intravenous immunoglobulin. eGFR at time of alemtuzumab administration was 35 mL/min/1.73 m² (IQR, 30-42) and stabilized or improved in 10 of 12 recipients within 12 months. Proteinuria was stable in the year after alemtuzumab. At 3-year follow-up, the death-censored graft survival was 68% (uncensored graft survival was 58%). Five cases of 10 cases that could be evaluated at 3-year follow-up had stable eGFR (on average 44 mL/min at 12 months and 42 mL/min at 36 months). Alemtuzumab was generally well tolerated and only 2 cases of opportunistic infections were noted. One case of symptomatic parvovirus B infection and 1 case of BK viral infection occurred, which both cleared at follow-up. In conclusion, alemtuzumab may be of value as a second-line treatment for late ABMR with rapid loss of eGFR.

Herpes Zoster in Solid Organ Transplantation: Incidence and Risk Factors

Background

Studies on herpes zoster (HZ) incidence in solid organ transplant (SOT) recipients report widely varying numbers. We investigated HZ incidence, severity, and risk factors in recipients of four different SOTs, with a follow-up time of 6-14 years.

Methods

Records of 1,033 transplant recipients after first heart (HTx: n = 211), lung (LuTx: n = 121), liver (LiTx: n = 258) and kidney (KTx: n = 443) transplantation between 2000 and 2014 were analyzed for VZV-PCR, clinical signs of HZ, and complications.

Results

HZ was diagnosed in 108 of 1,033 patients (10.5%): 36 HTx, 17 LuTx, 15 LiTx, and 40 KTx recipients. Overall HZ incidence rate after HTx (30.7 cases/1,000 person-years (PY)), LuTx (38.8 cases/1,000 PY), LiTx (22.7 cases/1,000 PY) and KTx (14.5 cases/1,000 PY) was significantly higher than in the general 50-70 year population. Multivariable analysis demonstrated age ≥50 years at transplantation (p = 0.038, RR 1.536), type of organ transplant (overall p = 0.002; LuTx p = 0.393; RR 1.314; LiTx p = 0.011, RR 0.444; KTx p = 0.034, RR 0.575), CMV prophylaxis (p = 0.043, RR 0.631) and type of anti-rejection therapy (overall p = 0.020; methylprednisolone p = 0.008, RR 0.475; r-ATG p = 0.64, RR1.194) as significant risk factors. Complications occurred in 33 of 108 (31%) patients (39% of HTx, 47% of LuTx, 20% of LiTx, 20% of KTx): post-herpetic neuralgia, disseminated disease, and cranial nerve involvement.

Conclusion

HZ incidence and severity in SOT recipients are most pronounced after heart and lung transplantation, in older patients, and when CMV prophylaxis is lacking.

Comparison of Alemtuzumab and Anti-thymocyte Globulin Treatment for Acute Kidney Allograft Rejection

Rabbit anti-thymocyte globulin (rATG) is currently the treatment of choice for glucocorticoid-resistant, recurrent, or severe acute allograft rejection (AR). However, rATG is associated with severe infusion-related side effects. Alemtuzumab is incidentally given to kidney transplant recipients as treatment for AR. In the current study, the outcomes of patients treated with alemtuzumab for AR were compared with that of patients treated with rATG for AR. The patient-, allograft-, and infection-free survival and adverse events of 116 alemtuzumab-treated patients were compared with those of 108 patients treated with rATG for AR. Propensity scores were used to control for differences between the two groups. Patient- and allograft survival of patients treated with either alemtuzumab or rATG were not different [hazard ratio (HR) 1.14, 95%-confidence interval (CI) 0.48–2.69, p = 0.77, and HR 0.82, 95%-CI 0.45–1.5, p = 0.52, respectively). Infection-free survival after alemtuzumab treatment was superior compared with that of rATG-treated patients (HR 0.41, 95%-CI 0.25–0.68, p < 0.002). Infusion-related adverse events occurred less frequently after alemtuzumab treatment. Alemtuzumab therapy may therefore be an alternative therapy for glucocorticoid-resistant, recurrent, or severe acute kidney transplant rejection.

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.

Sotrastaurin in calcineurin inhibitor-free regimen using everolimus in de novo kidney transplant recipients

Sotrastaurin, a novel selective protein-kinase-C inhibitor, inhibits early T cell activation via a calcineurin-independent pathway. Efficacy and safety of sotrastaurin in a calcineurin inhibitor-free regimen were evaluated in this two-stage Phase II study of de novo kidney transplant recipients. Stage 1 randomized 131 patients (2:1) to sotrastaurin 300 mg or cyclosporine A (CsA). Stage 2 randomized 180 patients (1:1:1) to sotrastaurin 300 or 200 mg or CsA. All patients received basiliximab, everolimus (EVR) and prednisone. Primary endpoint was composite efficacy failure rate of treated biopsy-proven acute rejection, graft loss, death or lost to follow-up. Main safety assessment was estimated glomerular filtration rate (eGFR) by MDRD-4 at Month 12. Composite efficacy failure rates at 12 months were higher in sotrastaurin arms (Stage 1: 16.5% and 10.9% for sotrastaurin 300 mg and CsA; Stage 2: 27.2%, 34.5% and 19.4% for sotrastaurin 200 mg, 300 mg and CsA). eGFR was significantly better in sotrastaurin groups versus CsA at most time points, except at 12 months. Gastrointestinal and cardiac adverse events were more frequent with sotrastaurin. Higher treatment discontinuation, deaths and graft losses occurred with sotrastaurin 300 mg. Sotrastaurin combined with EVR showed higher efficacy failure rates and some improvement in renal allograft function compared to a CsA-based therapy.

Effect of a single intraoperative high-dose ATG-Fresenius on delayed graft function in donation after cardiac-death donor renal allograft recipients: a randomized study

OBJECTIVES

Reducing the incidence of delayed graft function after transplant with donation after cardiac death donor renal allografts would facilitate managing recipients during their first weeks after a transplant. To reduce this incidence, in most studies, induction therapy with depleting anti-T-lymphocyte antibodies is coupled with a reduction of the dosage of the calcineurin inhibitor. The separate effect of anti-T-cell therapy on the incidence and duration of delayed graft function is therefore difficult to assess.

PATIENTS AND METHODS

We performed a randomized study to evaluate the effect of a single intraoperative high-dose of anti-T-lymphocyte immunoglobulin (ATG)-Fresenius (9 mg/kg body weight) on the incidence of delayed graft function. Eligible adult recipients of a first donation after cardiac death donor renal allograft were randomly assigned to ATG-Fresenius or no induction therapy. Maintenance immunosuppression consisted of tacrolimus, in an unadjusted dose, mycophenolate mofetil, and steroids.

RESULTS

The study was prematurely terminated because of a lower-than-anticipated inclusion rate. Baseline characteristics were comparable in the ATG-Fresenius group (n=28) and the control group (n=24). Twenty-two patients in the ATG-Fresenius group (79%) had delayed graft function, compared with 13 in the control group (54%; P = .06). Allograft and patient survival were comparable in both groups. Serious adverse events occurred more frequently in the ATG-Fresenius group than they did in the control group (57% vs 29%; P < .05).

CONCLUSIONS

Intraoperative administration of a single high-dose of ATG-Fresenius in donation after cardiac death donor renal allograft recipients, followed by triple immunosuppression with an unadjusted tacrolimus dose, seems ineffective to reduce the incidence of delayed graft function. Moreover, this was associated with a higher rate of serious adverse events (EudraCT-number, 2007-000210-36.).

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 calcineurin inhibitor tacrolimus allows the induction of functional CD4CD25 regulatory T cells by rabbit anti-thymocyte globulins

Rabbit anti-thymocyte globulins (rATG) induce CD4(+)CD25(+)forkhead box P3 (FoxP3(+)) regulatory T cells that control alloreactivity. In the present study, we investigated whether rATG convert T cells into functional CD4(+)CD25(+)FoxP3(+)CD127(-/low) regulatory T cells in the presence of drugs that may hamper their induction and function, i.e. calcineurin inhibitors. CD25(neg) T cells were stimulated with rATG or control rabbit immunoglobulin G (rIgG) in the absence and presence of tacrolimus for 24 h. Flow cytometry was performed for CD4, CD25, FoxP3 and CD127 and the function of CD25(+) T cells was examined in suppression assays. MRNA expression profiles were composed to study the underlying mechanisms. After stimulation, the percentage CD4(+)CD25(+)FoxP3(+)CD127(-/low) increased (from 2% to 30%, mean, P < 0.01) and was higher in the rATG samples than in control rIgG samples (2%, P < 0.01). Interestingly, FoxP3(+)T cells were also induced when tacrolimus was present in the rATG cultures. Blockade of the interleukin (IL)-2 pathway did not affect the frequency of rATG-induced FoxP3(+) T cells. The rATG tacrolimus-induced CD25(+) T cells inhibited proliferative responses of alloantigen-stimulated effector T cells as vigorously as rATG-induced and natural CD4(+)CD25(+)FoxP3(+)CD127(-/low) T cells (67% +/- 18% versus 69% +/- 16% versus 45% +/- 20%, mean +/- standard error of the mean, respectively). At the mRNA-expression level, rATG-induced CD25(+) T cells abundantly expressed IL-10, IL-27, interferon (IFN)-gamma, perforin and granzyme B in contrast to natural CD25(+) T cells (all P = 0.03), while FoxP3 was expressed at a lower level (P = 0.03). These mRNA data were confirmed in regulatory T cells from kidney transplant patients. Our findings demonstrate that tacrolimus does not negatively affect the induction, phenotype and function of CD4(+)CD25(+) T cells, suggesting that rATG may induce regulatory T cells in patients who receive tacrolimus maintenance therapy.

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.