Vaccine-associated corneal graft rejection following SARS-CoV-2 vaccination: a CDC-VAERS database analysis

PURPOSE

To evaluate the cases of corneal graft rejection following SARS-CoV-2 vaccination reported to Centers for Disease Control and Prevention Vaccine Adverse Event Reporting System.

METHODS

A descriptive analysis of the demographics, clinical history and presentation was performed. We evaluated the correlation between the vaccines and duration of vaccine-associated graft rejection (VAR) onset following vaccination using a one-way analysis of variance test. A post hoc analysis was performed between VAR onset-interval following vaccination dose and vaccine type. Finally, a 30-day cumulative incidence analysis was performed to assess the risk of VAR in short term following different doses, vaccines and type of corneal transplantation.

RESULTS

A total of 55 eyes of 46 patients were diagnosed with VAR following vaccination with BNT162b2 (73.91%) and mRNA-1273 (26.09%). The mean age of the patients was 62.76±15.83 years, and 28 (60.87%) were female. The patients diagnosed with VAR had undergone penetrating keratoplasty (61.82%), Descemet membrane endothelial keratoplasty (12.73%), descemet stripping endothelial keratoplasty (18.18%), anterior lamellar keratoplasty (3.64%) and corneal limbal allograft transplantation (1.82%). The mean time for VAR since penetrating and endothelial keratoplasty was 8.42±9.23 years and 4.18±4.40 years, respectively. 45.65% of the cases of VAR were reported after the second dose of vaccine. The duration of VAR onset was significantly shorter after the second dose compared with the first and booster doses (p=0.0165) and in patients who underwent endothelial keratoplasty compared with penetrating keratoplasty (p=0.041).

CONCLUSIONS

This study outlines a possible temporal relationship between corneal graft rejection and SARS-CoV-2 vaccination. An earlier onset of VAR was observed in patients who had a history of endothelial keratoplasty and following the second dose of vaccination.

Acute Cellular Rejection in A Kidney Transplant Recipient Following Vaccination with Inactivated SARS-CoV-2 Vaccine

SARS-CoV-2 vaccines are being administered worldwide. Most of the reported side effects are mild and self-limiting with few reported cases of severe adverse reactions. Here we report a case of acute cellular rejection in a kidney transplant recipient following vaccination with an inactivated SARS-CoV-2 vaccine. fifty- one years old man with autosomal dominant polycystic kidney disease, who had received a kidney transplantation from a living related donor, 3 years ago, presented with an impaired kidney function seven days after receiving the first dose of Sinovac's COVID-19 vaccine. Kidney transplant biopsy revealed acute cellular rejection. The allograft function completely recovered after treatment with steroids. The analysis and investigation of the complications and adverse reactions induced by anti-COVID-19 vaccines, could increase our understanding of the underlying pathogenesis.  DOI: 10.52547/ijkd.6915.

Pretransplant use of toripalimab for hepatocellular carcinoma resulting in fatal acute hepatic necrosis in the immediate postoperative period

Immune checkpoint inhibitors are increasingly used in the treatment of various solid tumors, including hepatocellular carcinoma (HCC). For liver transplant recipients, the safety of using immune checkpoint inhibitors before or after transplantation remains to be further explored. Former reports were mainly about posttransplant use of immune checkpoint inhibitors resulting in allograft rejection. Here we present one HCC patient who received toripalimab (an immune checkpoint inhibitor currently in phase 3 clinical trial for HCC) therapy before undergoing liver transplantation. He finally suffered fatal acute hepatic necrosis which is likely to be related to the acute immune rejection caused by the pretransplant use of toripalimab.

Acute renal transplant rejection following nivolumab therapy for metastatic melanoma

Cancers can develop the ability to evade immune recognition and destruction. Immune checkpoint inhibitors (ICIs) are drugs targeting these immune evasion mechanisms. ICIs have significantly improved outcomes in several cancers including metastatic melanoma. However, data on toxicities associated with allograft transplant recipients receiving ICI is limited. We describe a case of a 71-year-old woman who was diagnosed with metastatic melanoma 13 years after renal transplantation. She was commenced on the ICI nivolumab. She developed acute renal transplant rejection 15 days after administration of the first dose. She continues on haemodialysis but has demonstrated complete oncological response. This case demonstrates the risk of acute renal transplant rejection versus improved oncological outcomes. Patients and clinicians must consider this balance when initiating ICI therapy in allograft transplant recipients. Patients should be fully consented of the potential consequences of acute renal transplant rejection including lifelong dialysis.

Tacrolimus trough levels higher than 6 ng/mL might not be required after a year in stable kidney transplant recipients

Background

Little is known regarding optimal tacrolimus (TAC) trough levels after 1 year post-transplant in stable kidney transplant recipients (KTRs) who have not experienced renal or cardiovascular outcomes. This study aimed to investigate the effect of 1-year post-transplant TAC trough levels on long-term renal and cardiovascular outcomes and opportunistic infections in stable KTRs.

Methods

KTRs receiving TAC with mycophenolate-based immunosuppression who did not experience renal or cardiovascular outcomes within 1 year post-transplant were enrolled from a multicenter observational cohort study. Renal outcome was defined as a composite of biopsy-proven acute rejection, interstitial fibrosis and tubular atrophy, and death-censored graft loss. Cardiovascular outcome was defined as a composite of de novo cardiomegaly, left ventricular hypertrophy, and cardiovascular events. Opportunistic infections were defined as the occurrence of BK virus or cytomegalovirus infections.

Results

A total of 603 eligible KTRs were divided into the low-level TAC (LL-TAC) and high-level TAC (HL-TAC) groups based on a median TAC level of 5.9 ng/mL (range 1.3–14.3) at 1 year post-transplant. The HL-TAC group had significantly higher TAC trough levels at 2, 3, 4, and 5 years compared with the levels of the LL-TAC group. During the mean follow-up of 63.7 ± 13.0 months, there were 121 renal outcomes and 224 cardiovascular outcomes. In multivariate Cox regression analysis, LL-TAC and HL-TAC were not independent risk factors for renal and cardiovascular outcomes, respectively. No significant differences in the development of opportunistic infections and de novo donor-specific anti-human leukocyte antigen antibodies and renal allograft function were observed between the two groups.

Conclusions

TAC trough levels after 1 year post-transplant remained at a similar level until the fifth year after kidney transplantation and were not directly associated with long-term outcomes in stable Korean KTRs who did not experience renal or cardiovascular outcomes. Therefore, in Asian KTRs with a stable clinical course, TAC trough levels higher than approximately 6 ng/mL might not be required after a year of kidney transplantation.

The successful use of pembrolizumab in a renal transplant recipient with metastatic melanoma

We report a case in which a renal transplant recipient with metastatic melanoma had an excellent response to treatment with second line programmed cell death protein 1 (PD-1) inhibitor therapy, pembrolizumab. Acute cellular allograft rejection on initiation of PD-1 inhibitor was successfully reversed with methylprednisolone. By converting the patient to sirolimus and giving predose prednisolone, pembrolizumab was continued with stable renal function and an excellent oncological response. This case supports the efficacy of PD-1 inhibitors in patients who are chronically immunosuppressed, and suggests an approach to maintain transplant function.

Comparison of Kidney Transplant Function, Lipid Metabolism Disorders, and Glucose and Hemoglobin Concentration in Transplant Patients Treated With Proliferation Signal Inhibitor (Everolimus) or Calcineurin Inhibitor (Tacrolimus)

INTRODUCTION

After kidney transplantation (KTx) in patients with diagnosed cancers, calcineurin inhibitor tacrolimus (TAC) is replaced by sirolimus or everolimus (EV).

OBJECTIVE

The objective of the study was to compare the lipid metabolism parameters, KTx function, and glucose and hemoglobin (Hgb) levels in patients treated with EV to those on TAC.

MATERIAL AND METHODS

The retrospective study included 114 patients: 54 (17 women and 37 men) aged 57.6 years (18-77 years) treated with EV and 60 (18 women and 42 men) aged 49.6 years (20-77 years) treated with TAC as a control group. Their total cholesterol (TC), triglycerides (TG), fasting glucose (FG), serum creatinine (SCr), Hgb, and estimated glomerular filtration rate (eGFR) were assessed. In the patients treated with EV, the above values were evaluated before conversion, as well as 12 and 24 months following the switch and were evaluated once in the group treated with TAC.

RESULTS

In the EV-treated group, the mean preconversion values after 12 and 24 months were as follows: TC 5.06, 6.59, and 5.98 mmol/L; TG 1.90, 2.48, and 2.20 mmol/L; FG 94.95, 97.85, and 104.05 mg/dL; SCr 1.46, 1.44, and 1.56 mg/dL; Hgb 12.46, 12.83, and 13.36 g/dL; and eGFR 50.3, 50.6, and 50.5 mL/min/1.73 m². In the patients on TAC, the authors obtained the following values: TC 4.6 mmol/L; TG 1.87 mmol/L; glucose 104.13 mg/dL; SCr 1.51 mg/dL; Hgb 13.96 g/dL; and eGFR 56.6 mL/min/1.73 m².

CONCLUSIONS

After conversion from TAC to EV, increased values of TC and TG were observed after 1 year, while the increased values of TC, TG, SCr, Hgb, and FG were observed after 2 years.

Use of Ipilimumab and Pembrolizumab in Metastatic Melanoma in a Combined Heart and Kidney Transplant Recipient: A Case Report

New therapeutic agents such as checkpoint inhibitors are promising strategies in the treatment of metastatic melanoma. Transplant recipients are generally at higher risk of malign diseases. Limited data are available for the use and safety of these agents in this population. We describe a patient who had a stable transplant function over years after a combined heart and kidney transplantation. Immunosuppressive medications included tacrolimus and azathioprine and were later switched to sirolimus and azathioprine. Metastatic melanoma was diagnosed; after detailed explanation of the potential risk, the patient was initially treated with the anti-cytotoxic T-lymphocyte antigen-4 (CTLA-4) antibody ipilimumab but experienced an acute kidney graft rejection and rapid progression. Rejection therapy with high-dose corticosteroids was successful, and kidney function was stabilized. Because of the urgent request of the patient for additional therapy, he received a PD-1 inhibitor. Acute kidney graft rejection resulted, with indication for acute dialysis. He developed severe candida pneumonia and died despite extensive antimicrobial therapy. Checkpoint inhibitors have become the standard in a broad entity of tumors. Organ transplant patients are at higher risk of developing malignant diseases. Limited data are available for the use of checkpoint inhibitors in this subgroup, and the use of checkpoint inhibitors is associated with a high risk of graft rejection.

Immune Checkpoint Inhibitors and the Risk of Allograft Rejection: A Comprehensive Analysis on an Emerging Issue

BACKGROUND

It is well known that the state of immune tolerance induced by broad immunosuppression to prevent allograft rejection leads to an increased risk of the development of cancer. One of the most promising new areas of cancer treatment has been the development of immune checkpoint inhibitors that target the cytotoxic T-lymphocyte-associated antigen 4 and programmed cell death protein 1/programmed death-ligand 1 (PD-L1) pathways. As a logical consequence, growing interest in these agents translated into their implementation in patients with transplant-related malignancies. Because of overlapping and perhaps mutually exclusive mechanisms of action of transplant immunosuppression and cancer immunomodulation, it is critical to examine these interactions.

MATERIALS AND METHODS

We carried out a systematic search for review articles and case reports published between July 2014 and November 2017 using three engines: Usearch, PubMed, and Up-to-date.

RESULTS

Overall, there were 20 cases with 12 allograft rejections. The rejection rate associated with nivolumab was 73% (8/11) and with pembrolizumab it was 100% (2/2). The use of ipilimumab did not lead to rejection in any instance (0/4, 0%). Of the two patients treated with the sequential use of ipilimumab/nivolumab, one lost his allograft, yielding a rejection rate of 50%. The sequential use of ipilimumab/pembrolizumab led to a rejection rate of 100% (1/1, 100%).

CONCLUSION

The use of agents that act on the PD-L1 pathway are contraindicated in the face of solid organ allografts because of unacceptably high rates of irreversible allograft rejection. It appears that the use of ipilimumab may be tolerated as the mechanism is different from that of the PD-L1 agents.

IMPLICATIONS FOR PRACTICE

Transplant rejection is a complex process that puts stress on patients and their families and can lead to tragic results. Significant advancements in the field of immunosuppression have led to the engenderment of agents devised to extend the survival of transplant recipients. The advent of immunomodulators in cancer therapy has been paradigm-shifting; however, because of their mechanism of action, their use must be carefully considered in patients with allografts and concomitant cancer. It appears that ipilimumab can be administered safely in these patients but that agents acting on the programmed death-ligand 1 pathway are contraindicated because of high rates of irreversible rejection.

False Elevation of the Blood Tacrolimus Concentration, as Assessed by an Affinity Column-mediated Immunoassay (ACMIA), Led to Acute T Cell-mediated Rejection after Kidney Transplantation

Tacrolimus is the most commonly used immunosuppressant. Because of its narrow therapeutic range, it is necessary to frequently monitor its concentration. We report the case of a 25-year-old man who underwent kidney transplantation whose tacrolimus concentrations, as measured by an affinity column-mediated immunoassay, were falsely elevated. As we reduced the dose of tacrolimus, the recipient developed T cell-mediated rejection. Using the same blood samples, an enzyme-multiplied immunoassay technique showed that the patient's levels of tacrolimus were extremely low. A further examination indicated that the false increase in the tacrolimus concentration was likely due to an unknown interfering substance. We administered methylprednisolone and antithymocyte-globulin. The patient's serum creatinine level decreased and remained stable after these treatments.

Conversion from tacrolimus to everolimus with complete and early glucocorticoid withdrawal after kidney transplantation: a randomised trial

BACKGROUND

While conversion from cyclosporine to everolimus is well documented, conversion from tacrolimus has been poorly studied. In this randomised, controlled trial the safety and tolerability of switching from tacrolimus to everolimus with glucocorticoid withdrawal after living-donor kidney transplantation was studied.

METHODS

A total of 194 patients were planned to be randomised 1:1 to either continue tacrolimus or to convert to everolimus at month 3 after transplantation. At randomisation, all patients received tacrolimus, mycophenolate mofetil and prednisolone. Everolimus was started in a dose of 1.5 mg twice daily, aiming for predose concentrations of 4-7 ng/ml. Prednisolone was gradually withdrawn in both groups.

RESULTS

The trial was stopped prematurely after the inclusion of 60 patients. The interim analysis showed an unacceptably high rejection rate in the everolimus group as compared with the control group: 30.0% vs. 6.7% (95% CI: 0.047-0.420; p = 0.045). An additional 8 patients stopped everolimus because of toxicity. At the end of follow-up (month 12) only 12 (40%) patients assigned to everolimus were still on the study drug.

CONCLUSIONS

Conversion from tacrolimus to everolimusbased immunosuppression with withdrawal of prednisolone three months after kidney transplantation results in an unacceptably high risk of acute rejection and causes considerable toxicity. Based on our findings, such a switch strategy cannot be recommended.

Sarcoidosis and Wound Healing After Cellulitis of the Lower Limb: Is Methotrexate Responsible for Skin Graft Failure?

The authors report the case of a 53-year-old man with diffuse cutaneous and mediastinal pulmonary sarcoidosis and well-controlled steroid-induced diabetes. He was hospitalized for cellulitis of his left leg. His standard treatment for sarcoidosis consisted of prednisone and methotrexate. Prednisone was stopped at his admission. He received antibiotics for 4 weeks to treat the cellulitis. In parallel, the leg wound was treated with daily silver sulfadiazine applications until necrosis removal, then by skin autografting. Four successive procedures were performed, but all failed despite lack of surgical problem or local infection. Methotrexate was stopped after the fourth grafting procedure failed; the fifth, and final, autografting procedure was successfully performed.

Cardiac allograft rejection as a complication of PD-1 checkpoint blockade for cancer immunotherapy: a case report

INTRODUCTION

The increased availability of immunotherapeutic agents for the treatment of a wide array of cancer in the general oncology practice setting will reveal rare and unique toxicities.

MATERIALS AND METHODS

The mechanism of cardiac allograft rejection in the context of PD-1 antibody therapy was explored in a patient with cutaneous squamous cell cancer complicating long-standing cardiac allograft. Immune cell infiltrate in the myocardium and peripheral blood lymphocyte repertoire were assessed using myocardial biopsy and temporal analysis of peripheral blood samples. The efficacy of high-intensity immunosuppression to reverse graft rejection was explored.

RESULTS

Endomyocardial biopsy showed acute moderate diffuse cellular rejection with a predominant population of CD3+, CD8+ and CD4+ infiltrating lymphocytes; peripheral blood circulating lymphocytes showed a high frequency of proliferating and activated CD8+ T cells expressing PD-1 compared to a normal control. There was no difference in the activation and proliferation of CD4+ T cells compared to a normal control. Cardiac function improved following high-intensity immunosuppression and patient survived for up to 7 months after discontinuation of nivolumab.

CONCLUSIONS

Immune checkpoint inhibitors should be avoided in allograft recipients but high-intensity immunosuppression is effective to salvage allograft rejection induced by these agents.

Corneal graft rejection in a patient treated with nivolumab for primary lung cancer

We report the case of a 58-year-old woman treated with nivolumab for an unresectable squamous non-small cell lung cancer, after first-line cisplatin and gemcitabine combination chemotherapy. This woman had a history of left corneal graft. After 9 cycles of nivolumab, the patient described decreased visual acuity in the left eye with watering and conjunctival erythema. Ophthalmological examination revealed chronic corneal graft rejection. The patient was then treated with an intravenous bolus of corticosteroids (500mg of methylprednisolone) for 3 days, followed by oral prednisone for 4 weeks and subconjunctival corticosteroid injections every 48h, while treatment with nivolumab was discontinued. No clinical benefit was observed 4 weeks later and the corneal graft became totally unfunctional despite of the therapy. We hypothesise that the treatment was started too late. To our knowledge, this is the first reported case of corneal graft rejection related to nivolumab.

Impact of the reduction of calcineurin inhibitors on renal function in heart transplant patients: a systematic review and meta-analysis

AIMS

Calcineurin inhibitors (CNIs) taken after heart transplantation lead to excellent short-term outcomes, but long-term use may cause chronic nephrotoxicity. Our aim was to identify, appraise, select and analyse all high-quality research evidence relevant to the question of the clinical impact of CNI-sparing strategies in heart transplant patients.

METHODS

We carried out a systematic review and meta-analysis of randomized controlled trials on CNI reduction in heart transplant recipients. Primary outcomes were kidney function and acute rejection after 1 year. Secondary outcomes included graft loss, all-cause mortality and adverse events.

RESULTS

Eight open-label studies were included, with 723 patients (four tested de novo CNI reduction and four maintenance CNI reduction). Calcineurin inhibitor reduction did not improve creatinine clearance at 12 months 5.46 [-1.17, 12.03] P = 0.32 I(2)  = 65.4%. Acute rejection at 12 months (55/360 vs. 52/332), mortality (18/301 vs. 15/270) and adverse event rates (55/294 vs. 52/281) did not differ between the low-CNI and standard-CNI groups. There was significant benefit on creatinine clearance in patients with impaired renal function at 6 months [+12.23 (+5.26, +18.82) ml min(-1) , P = 0.0003] and at 12 months 4.63 [-4.55, 13.82] P = 0.32 I(2)  = 75%.

CONCLUSIONS

This meta-analysis did not demonstrate a favourable effect of CNI reduction on kidney function, but there was no increase in acute rejection. To provide a better analysis of the influence of CNI reduction patterns and associated treatments, a meta-analysis of individual patient data should be performed.

Peginterferon alpha-2b and acute allograft failure in a heart transplant recipient

Reports of heart transplant recipients with hepatitis C viral infection treated with peginterferon alpha-2b and ribavirin are very rare. We report a fatal case of acute allograft failure and hepatitis C viral infection in a 50-year-old orthotopic heart transplant recipient. At autopsy, the patient was found to have patent coronary arteries, diffuse severe fatty degeneration of heart myocytes, and no evidence of cellular or humoral rejection, confirming this as a fatal case of cardiotoxicity from peginterferon alpha-2b.

Modifying cyclosporine associated renal allograft dysfunction

Transplantation is accepted therapy for chronic kidney disease. However the essential immunosuppressive agents for graft survival have their own side-effects. Renal biopsy is a reliable tool for diagnosing cyclosporine (CsA) nephrotoxicity. To present our observations on CsA toxicity in renal allograft biopsies, we studied prospectively 207 renal allograft biopsies performed for graft dysfunction as per Ahmedabad Tolerance Induction Protocol (ATIP) and compared them to 50 controls from January to October 2007. The ATIP comprised donor specific leucocyte infusions, low dose target specific irradiation; non-myeloablative condi-tioning with Anti-T +/- B cell antibodies followed by intraportal administration of cultured donor bone marrow (BM) +/- adipose tissue derived mesenchymal stem cells. Renal transplantation was performed following negative lymphocytotoxicity cross-matching. The post-transplant immunosuppressive agents included CsA 2.5 +/- 0.5 mg/kg BW/day and prednisone 0.2 mg/kg BW/day. The controls were transplanted using standard triple immunosuppressive agents including CsA 5 +/- 1 mg/Kg BW/day, prednisone 0.6 mg/kg BW/day, and MMF/ Azathioprine. The Institutional Review Board approved the ATIP. The biopsies were categorized into 2 groups; group A (N=97): performed < 6 months, group B (N= 160), > 6 months posttransplant. Acute CsA toxicity was observed in group A: 2.5% ATIP and 11.1% controls; group B: 16.2% ATIP and 8.8% controls. Chronic CsA toxicity was observed in group B: 10.8 % ATIP and 17.6 % controls. Acute toxicity was more in the ATIP, while chronic toxicity was more in the controls. CsA doses were reduced post-biopsy and resulted in improved graft function evaluated by serum creatinine. We conclude that CsA nephrotoxicity evaluated by allograft biopsy resulted in allograft function recovery by decreasing the cyclosporine dose, and the ATIP decreased the incidence of CsA nephrotoxicity.

[Preliminary study on cardiac allograft rejection in mice by Extractum trametes robiniophila murr]

OBJECTIVE

To study the effect of Extractum trametes robiniophila murr on cardiac allograft rejection in mice.

METHODS

All abdominal heterotopic heart transplantation models were divided into three groups as follows: (A) Extractum trametes robiniophila murr group. (B) Rejection group. (C) Isograft group. In each group, mean survival times (MST) of transplanted hearts and their pathologic histological changes at postoperative fifth day were observed. With fluoroimmunoassay, granzyme B and CD8(+) expressions were examined.

RESULTS

The MST of heart allografts in group A were (6.38 +/- 0.69) d, significantly shorter than that of group B [(8.31 +/- 0.59) d] (P < 0.01). In group A, acute rejection was present in advance; transplanted hearts were seriously damaged into acute rejection pathological grade 3, and CD8(+) T lymphocytes infiltrated diffusely and the expression of granzyme B increased significantly as compared with other groups.

CONCLUSIONS

Exclusive application of Extractum trametes robiniophila murr can promote the acute rejection of graft in early phase of postoperation, and the mechanism may be the promoted proliferation and infiltration of CD8(+) T lymphocytes and the increased expression of granzyme B.

Immune-mediated liver dysfunction after antiviral treatment in liver transplanted patients with hepatitis C: allo or autoimmune de novo hepatitis?

BACKGROUND

The recurrence of hepatitis C after liver transplantation is extremely frequent. Antiviral therapy combining pegylated-interferon with ribavirin is therefore increasingly used in these patients. It has been recently reported, however, that during antiviral treatment a hepatic immune-mediated liver dysfunction, similar to "de novo" autoimmune hepatitis, may develop in a few transplanted patients.

PATIENTS AND METHODS

Three patients, treated with pegylated-interferon alpha-2a and ribavirin for recurrent hepatitis C after liver transplantation, developed an aggressive hepatitis with clinical, biochemical, and histological features similar to those of autoimmune hepatitis.

RESULTS

In all three patients, a liver enzymes increase was evident after hepatitis C virus-RNA had become undetectable. Diagnosis of "de novo" autoimmune hepatitis was proposed, based on the presence of high-titre circulating autoantibodies and liver histology features. Following the introduction of a steroid therapy, clinical and biochemical parameters progressively improved. Hepatitis C virus infection, however, relapsed after a few months in all the patients.

CONCLUSIONS

Following liver transplantation, antiviral therapy with pegylated-interferon alpha-2a and ribavirin for recurrent hepatitis C may be associated, in a few patients, with severe immune-mediated graft dysfunction similar to autoimmune hepatitis.

Increased rejection rates in cardiac transplant associated with dexamethasone

BACKGROUND

Peri-operative immunosuppression in cardiac transplantation includes the use of intravenous methylprednisolone. During a national shortage, intravenous dexamethasone was substituted for methylprednisolone at standard equivalencies. Methylprednisolone and dexamethasone are used interchangeably in many clinical settings; however, their equivalency has not been demonstrated.

METHODS

Forty-two consecutive cardiac transplant patients were studied retrospectively. All patients received standard triple immunosuppression. Eighteen patients received dexamethasone and 24 methylprednisolone. Twelve patients were included for comparison after the methylprednisolone shortage resolved. Endomyocardial biopsy (EMB) results graded as > or =1B (ISHLT classification) were considered positive for acute cellular rejection.

RESULTS

More patients who received dexamethasone as induction had cellular rejection (12/17; (70%) vs. 14/33; (42%); p=0.05). Four patients were excluded because of deaths unrelated to cardiac function. The increased rate of rejection seen during dexamethasone substitution declined after reinstitution of methylprednisolone (p=0.05).

CONCLUSIONS

Peri-operative high-dose dexamethasone in cardiac transplants was associated with higher rates of acute cellular rejection. The equivalencies of dexamethasone and methylprednisolone differ from accepted standards when used in pulse doses. Peri-operative use of glucocorticoids may rely on mechanisms that are different from those considered in the standard equivalency measures. Pulse doses of dexamethasone and methylprednisolone in transplantation may not be interchangeable at standard equivalencies.

Alpha-interferon therapy for chronic hepatitis C may induce acute allograft rejection in kidney transplant patients with failed allografts

BACKGROUND

In hepatitis C virus (HCV) positive kidney transplant (KT) patients, the use of alpha-interferon (alphaIFN) is contraindicated due to the risk of acute rejection (AR). Conversely, if these HCV(+) KT patients lose their allograft, re-transplantation might be contemplated provided alphaIFN therapy has been attempted.

METHODS

Between 01/01/1989 and 31/12/1994, 261 kidney transplantations were performed; of these 174 were HCV(-) (group I) and 87 were HCV(+) (group II).

RESULTS

At last follow-up (2006), in group I, the number of patients with a functioning graft, the number of patients who died with a functioning graft, and the number of patients who lost their graft before or after month (M) 12 were 92 (52.8%), 14 (8%), 20 (11.5%) and 48 (27.7%), respectively. In group II, the corresponding figures were 22 (25.3%; P < 0.0001), 8 (9.1%; ns), 9 (10.3%; ns) and 48 (55.3%; P < 0.0001). In group I, 19 of 48 (39.5%) patients with failed allografts after M12 underwent transplantectomy (TX) compared to 14 of 48 (29%; ns) in group II. In group II, 11 of 48 (23%) patients were offered alphaIFN therapy after their allograft failed: of these, four (36.3%) developed AR during alphaIFN therapy leading to TX. Histology, in addition to chronic allograft lesions, showed acute cellular and vascular lesions. In patients who were not offered alphaIFN therapy, TX was performed less frequently, i.e. in only six cases (16.2%).

CONCLUSIONS

We conclude that even alphaIFN-treated KT patients with a failed allograft can experience acute allograft rejection that requires transplantectomy during therapy.

Chronic ductopenic rejection in patients with recurrent hepatitis C virus treated with pegylated interferon alfa-2a and ribavirin

BACKGROUND

Interferon use for post liver transplantation (LT) recurrent hepatitis C (HCV) has not consistently been associated with acute cellular rejection (ACR). We examined the incidence of chronic ductopenic rejection (CR) in patients receiving pegylated interferon alfa-2a and ribavirin (PEG) to treat recurrent HCV.

METHODS

A chart review of 12 patients developing CR while receiving an escalating dose regimen of PEG with protocol liver biopsies every 6 months was conducted. Values are shown as median (range).

RESULTS

Twelve of the 70 patients treated with PEG developed CR. Median age at LT was 53 (37-63) years; immunosuppression consisted of tacrolimus or cyclosporine with prednisone. PEG was started at 3.6 (0.2-13.5) years after LT. Two patients had one episode of ACR before PEG. Four patients had first ACR while receiving PEG. CR was diagnosed after 12 (4-17) months of PEG; by then 8 patients had undetectable HCV-RNA. Tacrolimus and cyclosporine levels (ng/mL) were 7.9 (3.2-18.9) and 76 (71-93) before PEG, and 6.9 (3.7-9.7) and 130 (81-153) at CR. Six patients were treated more than 1 year with PEG; three had undetectable HCV-RNA when CR was diagnosed. Five patients are being treated for CR; one has been listed for LT; two patients were retransplanted. Five patients died as a result of sepsis partially related to CR.

CONCLUSIONS

Treatment with pegylated-interferon alpha-2a and ribavirin may trigger rapidly progressive CR in patients with therapeutic immunosuppressive trough levels, with or without first inducing ACR.

Stable Kidney Function in the Second Decade After Kidney Transplantation While on Cyclosporine-Based Immunosuppression

BACKGROUND

Calcineurin inhibitors (CNIs) have been the mainstay of immunosuppressive protocols in kidney transplantation over the past 20 years. However, in some recipients, the adverse effects of CNIs contribute to chronic allograft nephropathy and death with function--the two leading causes of late graft loss. Other recipients maintain stable graft function.

METHODS

We studied the impact of continuing CNI-based immunosuppression in the second decade after kidney transplantation. From 1984 through 1996, a total of 1,263 patients underwent a primary kidney transplant at the University of Minnesota and received cyclosporine-based immunosuppression. Antibody induction was used only in deceased donor recipients.

RESULTS

The actuarial 20-year patient survival rate was 38%; graft survival, 30%; and death-censored graft survival, 60%. The annual mean serum creatinine level for recipients whose grafts survived > or =1 year remained stable, although recipients with a history of > or =1 acute rejection episode had a higher serum creatinine level vs. recipients who were rejection-free. The annual mean calculated creatinine clearance was also stable over time. In addition, for recipients who were acute rejection-free, chronic allograft nephropathy/chronic rejection was only responsible for 9% of graft losses.

CONCLUSIONS

Our study suggests that some kidney transplant recipients tolerate long-term CNI-based immunosuppression with stable creatinine levels. Identifying certain recipients' predisposition to CNI toxicity and individualizing immunosuppressive therapy may be important in order to improve long-term kidney function, while simultaneously preserving low short-term acute rejection rates.

[Treatment of hepatitis C in patients on renal replacement therapy]

The prevalence of hepatitis C virus infection among patients on hemodialysis is about ten times higher than in the normal population. The infection can induce chronic glomerulonephritis, as an extrahepatic manifestation, which can lead to end stage renal disease. However, in the majority of the patients hepatitis C virus is acquired as a nosocomial infection during the hemodialysis. In most of the infected patients the liver enzymes are usually normal and need regular screening of the hepatitis C antibody to detect the infection. Despite of the normal liver enzymes, the liver disease may progress to cirrhosis. A part of the patients wait for renal transplantation. The immunosuppressive treatment after the renal transplantation results in a significantly increased viral replication which might induce further progression of the liver disease. Interferon treatment given after the transplantation can induce rejection and graft failure. Therefore the antiviral treatment should be administered during the hemodialysis or earlier. Only limited data are available with the treatment of patients with impaired renal function. Mostly alfa-interferon was used in these patients. Due to the impaired renal clearance and higher serum concentration interferon seems to be more effective, but less tolerable in patients with end stage renal disease than in normal patients. Ribavirin is also excreted exclusively by the kidney and the anemia is even more pronounced in these patients, therefore it is contraindicated in patients on hemodialysis. The pharmacokinetics of the pegylated interferon alfa-2a is very advantageous for the patients with end stage renal disease. The safety and efficacy of peginterferon alfa-2a is now being confirmed in many publications.

Relationship between acute rejection and cyclosporine or mycophenolic acid levels in Japanese heart transplantation

BACKGROUND

Cyclosporine (CsA), Mycophenolate mofetil (MMF) and prednisolone (PSL) are widely used for the prevention of acute rejection after heart transplantation. Recently, the serum concentration - time curves (AUC) of CsA and MMF have been demonstrated to be precise predictors of acute rejection.

METHODS AND RESULTS

Fourteen heart transplant patients were treated concomitantly with CsA, MMF, and PSL between May 1999 and November 2005 at the National Cardiovascular Center and of them 3 had acute rejection episodes [International Society for Heart & Lung Transplantation grade 3a]. Two patients (man in his 30 s; woman in her 40 s) had acute rejection with a mycophenolic acid (MPA) AUC(0-12 h) <30 microg x h x ml(-1) and low CsA AUC (AUC(0-4 h); 2,408 ng x h x ml-1, 1,735 ng x h x ml-1). However, 1 patient (man in his 30 s) with a high CsA AUC(0-4 h) (4,019 ng x h x ml-1) did not develop cardiac allograft rejection even if the MMF was temporarily stopped. These 3 patients were investigated to evaluate the relationship between acute rejection and pharmacokinetic parameters, including the CsA C0, C2, AUC(0-4 h) and MPA AUC(0-12 h).

CONCLUSIONS

The findings suggest that a high CsA AUC(0-4 h) may prevent rejection of a cardiac allograft, even if MMF is stopped or drastically reduced.

Rejection under alpha interferon therapy in liver transplant recipients

Interferon alpha (IFN) is the corner stone drug for the treatment of recurrent hepatitis C (HCV) in liver transplant (LT) recipients. One of its serious potential adverse effects is acute and chronic rejection. The aim of this study was to review our experience using IFN-based therapy, in order to examine the incidence and the risk factors for rejection, and the outcome of patients who developed rejection. Between September 1990 and December 2004, 70 LT recipients were treated. Patients started antiviral treatment 16 (1-137) months after LT. Histological follow-up was available in all patients according to protocol biopsies. Rejection was diagnosed and graded according to Banff classification. Twenty-one percent of patients developed acute rejection (5 mild, 9 moderate and 1 severe) during IFN-based therapy. Patients were treated for 8 (1-15) months prior to rejection. Previous history of acute rejection before IFN therapy and treatment with pegylated-IFN was significantly associated with rejection (p = 0.04 and p = 0.02, respectively). The rejection was successfully treated in 87% of patients. No chronic rejection or graft losses were observed. Acute rejection under IFN-based therapy often occurs in LT recipients, but early diagnosis with protocol biopsies and early treatment can lead to a favorable outcome.

CD20+ Lymphocytes in Renal Allografts Are Associated with Poor Graft Survival in Pediatric Patients

BACKGROUND

The presence of CD20+ lymphocyte renal allograft infiltrates has been associated with steroid-resistant rejection and poor graft survival. We quantified the number of CD20+ lymphocytes in renal allograft biopsies and correlated the results with graft survival. We also determined the relationships between CD20+ lymphocytes and acute cellular rejection versus antibody-mediated rejection.

METHODS

We examined 45 biopsy samples from 31 pediatric patients biopsied for suspicion of rejection from November 2001 to November 2004. Immunohistochemical staining for CD20 and C4d was performed on all biopsies; CD20+ cell density per high-power field (hpf) was determined for each core. Patient graft status was followed postbiopsy and documented for graft survival or failure using the cutoff date of December 31, 2005.

RESULTS

Patients with 2-10 and 11-100 CD20+ cells/hpf had worse graft survival in Kaplan-Meier analysis with a hazard ratio 4.56 (CI 1.07-19.35) two years postbiopsy compared to those with 0-1 cells/hpf (P = 0.02). The presence of CD20+ lymphocytes was significantly associated with acute cellular rejection (P = 0.0001) and not associated with antibody-mediated rejection (P = 0.16). Receiver-operating curve analysis confirmed > or =3 cells/hpf correlating with acute cellular rejection, yielding sensitivity 90% and specificity 76%.

CONCLUSIONS

This study shows a significant 4.5-fold risk of graft failure at two years postbiopsy with presence of > or =2 CD20+ cells/hpf. Moreover, > or =3 CD20+ lymphocytes were highly associated with acute cellular rejection. They may be functioning as professional antigen-presenting cells in the graft. In steroid-refractory cellular rejections, therapies that target B cells may prolong graft survival.

Treatment of recurrent hepatitis C after liver transplantation

Chronic hepatitis C virus (HCV) infection is the most common indication for liver transplantation in the United States and Europe, and more than 20,000 patients worldwide have undergone transplantation for complications of chronic hepatitis C. In North America, HCV accounts for 15% to 50% of the liver transplants performed in United States transplant programs. To maximize the long-term survival of liver transplant recipients who have HCV infection, eradication of infection is the ultimate goal. Pretransplant antiviral therapy with the goal of achieving viral eradication before transplantation is a consideration in some patients, especially those who have mildly decompensated liver disease. This article focuses on the management of liver transplant recipients who have HCV infection at the time of transplantation. Prophylactic and preemptive therapies, as well as treatment of established recurrent disease, are the strategies reviewed.

Long-term efficacy and safety of mycophenolate mofetil in liver transplant recipients with calcineurin inhibitor-induced renal dysfunction

Long-term survival after orthotopic liver transplantation (OLT) is mainly influenced by adverse events caused by immunosuppression. Several studies have shown the efficacy of mycophenolate mofetil (MMF) in improving calcineurin inhibitor (CI)-induced nephrotoxicity with concomitant reduction or withdrawal of CI. In this prospective study we assessed the long-term effect and safety of MMF. Thirty-two OLT recipients with significant renal impairment due to either cyclosporine A ( n=25) or tacrolimus ( n=7) were enrolled in this study. CIs were reduced stepwise by at least 70%. Mean serum creatinine had decreased from 2.63+/-0.39 to 1.74+/-0.34 mg/dl after 1 month, and this improvement was maintained within a follow-up period of 4.8+/-0.6 (range 3.1-6.0) years, without major immunological or non-immunological side effects. Of all participants, 88% showed a significant reduction, and 41% even a normalization, in their serum creatinine level. In addition, MMF conversion, within 6 months of OLT, appears to be crucial in order to improve or even normalize renal function. This study demonstrates the long-term efficacy and safety of MMF in OLT recipients with CI-induced nephropathy.

Mycophenolate mofetil monotherapy in liver transplant recipients: a single center experience

The long-term use of calcineurin inhibitors (CIs) is associated with significant morbidity in liver transplant recipients. Although mycophenolate mofetil (MMF) is well tolerated, two small studies reported an unacceptable rate of acute allograft rejection in liver transplant recipients receiving MMF monotherapy. In this study, we retrospectively investigated the safety and efficacy of MMF monotherapy in liver transplant recipients. We reviewed the medical records of all patients who underwent liver transplant at our institution. Sixteen patients were identified who received MMF either as monotherapy (n = 13) or with corticosteroids (n = 3; 2 of them for other comorbid conditions), and these patients were studied to determine the efficacy and complications. Fifteen (15/16) patients were converted from a CI to MMF because of renal insufficiency. Patients were converted to MMF monotherapy after a median of 2,056 days (range, 606-5,893) after liver transplantation. The median postconversion follow-up was 668 days (range, 60-1,509). Four patients required dialysis despite conversion; of those patients not requiring dialysis, serum creatinine stabilized and showed a trend toward improvement (2.51 +/- 1.12 mg/dL to 1.85 +/- .58 mg/dL, P = .1). However, there were 3 episodes (47, 107, and 1,203 days after conversion) of severe, irreversible allograft rejection after conversion resulting in death in 2 patients and necessitating retransplantation in 1 patient. There were no patient characteristics, except perhaps African-American race, that predicted the development of rejection. In conclusion, MMF monotherapy was associated with a significant risk (19%) of unpredictable, severe, and irreversible allograft rejection even among long-term transplant survivors. Caution should be exercised before converting patients to MMF monotherapy.

Non-complement- and complement-activating antibodies synergize to cause rejection of cardiac allografts

Alloantibodies (AlloAbs) are a clinically significant component of the immune response to organ transplants. In our experimental model, B10.A (H-2a) cardiac transplants survived significantly longer in C57BL/6 (H-2b) immunoglobulin knock-out (IgKO) recipients than in their wild-type (WT) counterparts. Passive transfer of a single 50-200-microg dose of complement-activating IgG2b AlloAbs to IgKO recipients reconstituted acute rejection of cardiac allografts. Although passive transfer of a subthreshold dose of 25 microg of IgG2b or a single 100-200-microg dose of non-complement-activating IgG1 AlloAbs did not restore acute rejection to IgKO recipients, a combination of these AlloAbs did cause acute graft rejection. Histologically, rejection was accompanied by augmented release of von Willebrand factor from endothelial cells. IgG1 AlloAbs did not activate complement on their own and did not augment complement activation by IgG2b AlloAbs. However, IgG1 AlloAbs stimulated cultured mouse endothelial cells to produce monocyte chemotactic protein 1 (MCP-1) and neutrophil chemoattractant growth-related oncogene alpha (KC). TNF-alpha augmented IgG1 induced secretion of MCP-1 and KC. These findings indicate that non-complement-activating AlloAbs can augment injury to allografts by complement-activating AlloAbs. Non-complement-activating AlloAbs stimulate endothelial cells to produce chemokines and this effect is augmented in the milieu of proinflammatory cytokines.

Tuberculosis in Egyptian kidney transplant recipients: study of clinical course and outcome

BACKGROUND

Tuberculosis (TB) is an important infection encountered post-transplantation especially in developing countries, with high incidences of morbidity and mortality. In this report, we study the risk factors and impact of TB on the outcome of kidney transplantation.

METHODS

Of 1200 live-donor Egyptian kidney transplantations, 45 (3.8%) patients developed post-transplant TB. Of these, five had had TB pre-transplantation and 40 were male. The mean age was 32.6 +/- 10.5 years. Primary immunosuppression treatment for 39 (86.7%) patients was cyclosporine (CsA).

RESULTS

The mean time interval between transplantation and TB diagnosis was 49.8 +/- 41.5 (range 2-180) months. In 86.7% of patients, TB was diagnosed one year post-transplantation. Urinary TB was the most common form (53%), while pleuropulmonary TB accounted for 38%. All post-transplant TB patients received a triple anti-tuberculous therapy (rifampicin, ethambutol and INH) with a favorable response in all but two patients who needed another 24-month course. Hepatotoxicity was seen in 11 patients, eight were mild with normalization after temporary withdrawal of rifampicin, and three cases were severe, but mortality was not attributable to hepatocellular failure. Twelve patients died, 11 of them due to unrelated causes. Chronic rejection occurred in more than half of the patients (55.6%), of whom 24 (96%) were CsA-treated, which can be attributed to rifampicin/CsA interaction. More than 35% of TB patients lost their graft as a result. Pre-transplant tuberculosis patients had a comparable post-transplant course.

CONCLUSIONS

TB is a common infection in renal transplant recipients with a peak incidence occurring one year post-transplant. Chronic rejection is a serious complication that had a negative impact on the graft survival, especially in CsA-treated recipients. INH prophylaxis is safe in pre-transplant TB. The post-transplantation outcome in the pre-transplant tuberculosis patients is no different from non-TB patients.

A role for effectors of cellular immunity in epimorphic regeneration of amphibian limbs

Immune modulation of regeneration of amphibian appendages is suggested, but not proven, by previous studies. Earlier studies have not demonstrated effects of treatments on both epimorphic regeneration and immune responses or restoration of regeneration by specific reversal of immunomodulation. Cyclosporin A (CsA) and interleukin-2 (IL-2) were used in this study to demonstrate the effects of immune suppression and its reversal, on allograft rejection and forelimb regeneration. When administered alone, CsA suppressed rejection of skin allografts and induced a dose-dependent retardation of regeneration. IL-2, administered alone, did not affect allograft rejection or regeneration. However, when combined with CsA, IL-2 abrogated or reversed effects of CsA on both allograft rejection and forelimb regeneration, in a dose-dependent manner. The selective focus of CsA's action and the ability of IL-2 to overcome and reverse these effects strongly suggest that T-lymphocytes participate in or contribute to expression of epimorphic regeneration of amphibian appendages. Further studies are required to better characterize this role.

Hormone therapy in men and risk of cardiac allograft rejection

Hormone therapy with leuprolide acetate (Lupron) is frequently used to treat prostate cancer, a common malignancy expected to be diagnosed in >180,000 men in the United States this year. In addition, testosterone supplementation is frequently recommended for adult men with reduced libido or impotence and decreased serum levels of testosterone. Although these hormone therapies are generally considered benign, we describe 3 cases of acute cardiac rejection temporally associated with the use of these drugs in men who have undergone cardiac transplantation. To our knowledge, this is the first such description of this phenomenon in the literature.

Immunisations in solid-organ transplant recipients

Solid-organ transplant recipients are at increased risk of various infectious diseases, some of which are vaccine preventable mmunisations are among the most efficient interventions available. Solid-organ tranplant recipients would greatly benefit from effective immunisations, provided the recommendations are based on a careful risk-benefit analysis in which the effectiveness of the vaccine is weighed against possible adverse reactions, including graft rejection. In this review, we summarise the data from studies on relevant immunisations in solid-organ transplant recipients. The major issues are the immunogenicity and safety of immunisations, the factors associated with poor immune response, and recommendations for immunisation schemes.

Increased early rejection rate after conversion from tacrolimus in kidney and pancreas transplantation

CONTEXT

A successful immunosuppression regimen for combined kidney and pancreas transplants is tacrolimus, mycophenolate mofetil, and prednisone. However, not all patients tolerate these immunosuppressants especially tacrolimus.

OBJECTIVE

To evaluate the efficacy of cyclosporine as a rescue agent for tacrolimus toxicity in combined kidney and pancreas transplants.

DESIGN

Retrospective.

SETTING

Single center.

PATIENTS

Thirty-five combined kidney and pancreas transplants were performed between July 1994 and January 1999. All patients were insulin dependent diabetics with end-stage renal disease. Twenty-eight (mean age: 36 years and 57% female) were available with at least 12 month follow-up.

INTERVENTIONS

Conversion to cyclosporine following renal (biopsy proven) or pancreatic dysfunction.

MAIN OUTCOME MEASURES

Toxicity, rejection rate, and patient/transplant organ survival.

RESULTS

Nineteen transplant recipients (68%) were continuously maintained on tacrolimus while nine (32%) required conversion to cyclosporine 75 +/- 20 days post-transplant. Reasons for conversion included: hyperglycemia (n=2), hemolytic-uremic syndrome (n=1), and severe tacrolimus nephrotoxicity (n=6). By 12 months post-transplant, the 19 patients maintained on tacrolimus had 5 rejections (26%). Three of the 9 patients (33%) converted to cyclosporine had an acute rejection prior to conversion. Seven of these 9 patients (78%; P=0.017 vs. patients maintained on tacrolimus) had rejections an average of 25 +/- 4 days post-conversion. Four of the 7 patients had no previous rejections prior to conversion. In spite of increased rejections, the 1- and 2-year patient/graft survivals were unchanged by converting.

CONCLUSIONS

Converting to cyclosporine from tacrolimus was associated with an increased risk of acute rejection especially within the first 30 days post conversion.

Enhancement of leukemia rejection by mice successfully treated for L1210 leukemia due to low dose compared to high dose VP-16

We have earlier shown that VP-16 combined with Cyclosporin A (CsA) produces tumor specific immunity to L1210 leukemia in BDF/1 mice [Slater LM, Sweet P, Stupecky M, Reynolds JT. Cyclosporin A/VP-16 produced immunity to L1210 leukemia: the participation of cytotoxic CD(8) T-lymphocytes, Clin Immunol Immunopathol 1995;75:239-45]. Our current studies, designed to determine the role of VP-16 independently of CsA in this effect show that increased dose intensity of VP-16, in the absence of CsA, improves the frequency of 60 day survival of treated mice but impairs the ability of 60 day surviving mice to reject L1210 leukemia challenge. This impairment is associated with progressive diminution of mitogen responses by spleen cells harvested from tumor free VP-16 treated mice.

Defining the risk of elective cyclosporine withdrawal in stable kidney transplant recipients

Although it is known that elective cyclosporine (CsA) withdrawal increases the risk for acute rejection, few studies have been large enough to identify risk factors for acute rejection after CsA withdrawal. We examined risk factors for acute rejection in 464 kidney transplant recipients who underwent elective CsA withdrawal. The incidence of acute rejection within 6 months of CsA withdrawal was 20/141 (14.2%) in the period January 1986 to May 1989, but only 14/323 (4.5%) since May 1989 (p = 0.0002). Among those transplanted since May 1989, the incidence was 5/20 (25%) for those with both 2 HLA-B and 2 HLA-DR mismatches, compared with only 9/298 (3.0%) for those with fewer mismatches (p < 0.0001). In Cox proportional hazards analysis, risk factors for acute rejection within 6 months, or at any time after elective CsA withdrawal, were date of transplant January 1986 to May 1989 (compared with more recently May 1989 to March 1999), younger age, obesity, as well as B and DR mismatches. Recipient race (83% were white), acute rejection during the first year before withdrawal (31%), mycophenolate mofetil (17%), and other variables failed to predict postwithdrawal acute rejection. We concluded that avoiding CsA withdrawal in the relatively small number of recipients with both 2 HLA-B and 2 HLA-DR mismatches could further reduce our already low incidence of acute rejection following elective CsA withdrawal.

Peripheral blood stem cell allograft rejection mediated by CD4(+) T lymphocytes recognizing a single mismatch at HLA-DP beta 1*0901

Little is known about the molecular characteristics of alloantigens recognized by alloreactive T cells mediating hematologic stem cell graft rejection. In particular, it has never been shown that such alloantigens can be encoded by HLA-DP beta alleles. Indeed, matching for HLA-DP antigens is generally not considered to be of functional importance for the outcome of allogeneic bone marrow or peripheral blood stem cell transplantation. In this study, a case of peripheral blood stem cell allograft rejection was investigated in which the patient and donor differed for a single mismatch at HLA-DP in the rejection direction. Patient-derived T lymphocytes circulating at the time of rejection showed direct ex vivo cytotoxic activity against donor-derived B-lymphoblastoid cells as well as other HLA-DP beta 1*0901--expressing targets. The presence of HLA-DP beta 1*0901--specific effectors in vivo was further confirmed by in vitro stimulation experiments. CD4(+) T-cell lines and clones with specific cytotoxic activity against HLA-DP beta 1*0901--expressing targets including donor B-lymphoblastoid cells were generated both by nonspecific and by donor-specific in vitro stimulation. Taken together, these data demonstrate that HLA-DP can be the target antigen of cytotoxic CD4(+) T lymphocytes involved in peripheral blood stem cell allograft rejection. (Blood. 2001;98:1122-1126)

Human T cells infiltrate and injure pig coronary artery grafts with activated but not quiescent endothelium in immunodeficient mouse hosts

BACKGROUND

We have previously demonstrated that human artery grafts transplanted to immunodeficient mice are infiltrated and injured by unsensitized allogeneic human T cells. We extended our investigations to human anti-porcine xenoresponses in this model.

METHODS

Pig coronary artery segments were interposed into the infrarenal aorta of severe combined immunodeficiency/beige mice. After 7 days, certain recipients were reconstituted with human leukocytes and/or treated with proinflammatory cytokines. The grafts were harvested after 1-70 days and examined by histology, immunohistochemistry, and morphometry.

RESULTS

Pig artery grafts from untreated mice had no evidence of injury, leukocytic infiltrate, or endothelial cell activation up to 70 days postoperatively, despite deposition of murine complement. Host reconstitution with human peripheral blood mononuclear cells resulted in a discrete population of circulating T cells that did not infiltrate or injure the grafts up to 28 days after adoptive transfer. Administration of porcine interferon-gamma for up to 28 days sustained the expression of graft vascular cell adhesion molecule-1 and major histocompatibility complex antigens, but did not initiate recruitment of human leukocytes. In contrast, treatment with human tumor necrosis factor for 7 days induced the de novo expression of porcine E-selectin by graft endothelial cells and elicited human T cell infiltration and human peripheral blood mononuclear cell-dependent vascular injury.

CONCLUSIONS

The human peripheral blood mononuclear cell-severe combined immunodeficiency/beige mouse model identifies a significant difference between human T cell allogeneic and xenogeneic responses in vivo. Xenografts with quiescent endothelium are not infiltrated or injured by T cells under the same conditions in which allografts are rejected. Activation of pig coronary artery endothelial cells by human tumor necrosis factor, but not porcine interferon-gamma, elicits cellular xenoresponses.

Clinical utility of monitoring tacrolimus blood concentrations in liver transplant patients

The relationship between the dose of tacrolimus, trough tacrolimus blood concentration, and selected clinical endpoints (acute rejection, nephrotoxicity, and other toxicities) were examined in a prospective, multicenter clinical trial to validate the use of an enzyme-linked immunosorbent assay (ELISA) for monitoring whole-blood concentrations of tacrolimus in liver transplant patients. A total of 111 subjects from six transplant centers were evaluated over 12 weeks posttransplantation. In addition to trough tacrolimus blood concentrations, hematocrit, ALT, AST, GGTP, alkaline phosphatase, total bilirubin, serum creatinine, BUN, serum potassium, serum magnesium, blood glucose, and serum albumin were also measured. The relationship between trough tacrolimus blood concentrations and clinical endpoints was analyzed using both a logistic regression model and a Cox proportional hazard model. By logistic regression analysis, a statistically significant (p = 0.0465) relationship between increasing trough tacrolimus blood concentrations and decreasing risk of acute rejection was demonstrated over a 7-day time window. Nephrotoxicity and other toxicities also demonstrated statistically significant relationships with trough tacrolimus blood concentrations. The results of the Cox analysis were consistent with the logistic regression analysis. Using receiver operator characteristic curves, trough tacrolimus concentrations as measured by the ELISA method were able to differentiate the occurrence of nephrotoxicity and toxicity from nonevents. To minimize nephrotoxicity of tacrolimus, it is necessary to maintain trough blood concentrations below 15 ng/ml. This study demonstrates that the ELISA method used to measure tacrolimus blood concentrations in this study provides information of predictive value for managing the risk of nephrotoxicity, other toxicity, and rejection in liver transplant patients.