Immunologic parameters and viral infections in patients desensitized with intravenous immunoglobulin and rituximab

Viral-specific cytotoxic T-cell responses in HLA-sensitized kidney transplant patients maintained on everolimus and low dose tacrolimus

BACKGROUND

Maintenance with "everolimus + reduced dose tacrolimus" (Ev + Tac_low ) was reported to reduce the risk of viral infections compared to (Tac + MMF). Here we examined viremia and viral-specific T-cell (viral-Tc) responses in patients treated with Ev + Tac_low v. Tac + MMF in highly-HLA sensitized patients.

METHODS

HLA sensitized (HS) kidney transplant patients were monitored pre- and post-transplant for viremia (CMV, BK and EBV) by PCR in 19 Ev + Tac_low and 48 Tac + MMF patients. For CMV PCR analysis, we compared infection rates in 19 Ev + Tac_low patients to 48 CMV D+/R- (#28) or CMV D-/R- (#20) Tac + MMF patients. CMV-Tc and EBV-Tc were evaluated by cytokine flow cytometry, and DSA levels by Luminex for selected patients in both groups.

RESULTS

CMV, EBV viremia rates were similar in Ev + Tac_low v. Tac + MMF patients, but BKV rates were significantly higher in Ev + Tac_low patients. No patient in either group developed BKAN or PTLD. CMV- & EBV-Tc decreased significantly after alemtuzumab induction but returned to pre-treatment levels 1-2 months post-transplant in most patients. de novo DSA was similar in both groups as were patient and graft survival and graft rejection.

CONCLUSIONS

CMV-Tc, EBV-Tc were similar in Ev + Tac_low and Tac + MMF patients. EBV and CMV viremia rates were similar over 1 year. BKV rates were significantly higher in Ev + Tac_low patients suggesting no benefit for Ev + Tac_low in enhancing viral specific Tc effector functions or limiting viral infections. This article is protected by copyright. All rights reserved.

Safety and Efficacy of Alemtuzumab Induction in Highly Sensitized Pediatric Renal Transplant Recipients

BACKGROUND

Studies show that alemtuzumab, a potent lymphocyte-depleting agent, is well tolerated in pediatric renal transplantation. We report on the use of alemtuzumab induction in highly HLA sensitized (HS) pediatric kidney transplant patients.

METHODS

Fifty pediatric renal transplants were performed from 1/2009-12/2014. 15 HS patients received IVIG (2 g/kg ×2 doses)/rituximab (375 mg/m ×1) for desensitization with alemtuzumab induction (15-30 mg, 1 dose, subcutaneous), whereas 35 nonsensitized patients received anti-IL-2R. Graft survival and infections were compared between 2 groups.

RESULTS

All HS patients had received a prior transplant and were older with lower risk for viral infections due to serostatus. Patient survival was 100%, and graft outcomes were similar with mean 1-year creatinine of 1.03 ± 0.45 versus 0.99 ± 0.6 (P = 0.48). Although a higher incidence of acute cellular rejection was seen in HS patients receiving alemtuzumab (P = 0.001), there was a nonsignificant difference in antibody-mediated rejection. White blood cell and absolute lymphocyte count were significantly lower in alemtuzumab group at 30 days (P < 0.0001) and at 1 year (P = 0.026 and P = 0.001), respectively. There was no significant difference in bacterial, viral, or fungal infections after transplant.

CONCLUSIONS

Alemtuzumab induction with desensitization led to nearly equivalent graft survival and functional outcomes in HS pediatric patients as nonsensitized patients receiving anti-IL-2R induction. With this small sample size, we observed significant reduction of white blood cell and absolute lymphocyte count up to 1 year posttransplant. The risk of infection was comparable between the 2 groups; however, patients who received alemtuzumab were older and at lower risk of viral infection due to serostatus.

Impact of Desensitization on Antiviral Immunity in HLA-Sensitized Kidney Transplant Recipients

Viral infections represent significant morbidity and mortality factors in kidney transplant recipients, with CMV, EBV, and BKV infections being most common. Desensitization (DES) with IVIg and rituximab with/without plasma exchange followed by kidney transplantation with alemtuzumab induction increased successful transplant rates in HLA-sensitized patients but may represent an increased risk for viral infections due to severe lymphocyte depletion. Here, we report on the posttransplant viral infection status in 372 DES versus 538 non-DES patients. CMV and EBV viremia were significantly lower in DES patients, while BKV viremia was similar. This trend was observed primarily in CMV sero(-), EBV sero(+), and sero(-) patients. No patient developed PTLD. The incidence of BKAN, allograft, and patient survival was similar in both groups. These viral infections were not associated with subsequent allograft rejection which occurred within 6 months after the infection. Conclusions. The IVIg + rituximab desensitization combined with alemtuzumab induction with triple immunosuppression maintenance does not increase the risk for CMV, EBV, and BKV infections. Possible factors include, in addition to posttransplant antiviral prophylaxis and PCR monitoring, presence of memory T cells and antibodies specific to CMV and likely EBV, NK cell-mediated ADCC despite lymphocyte depletion, elimination of EBV and CMV reservoirs by rituximab and alemtuzumab, and use of IVIg with antiviral properties.

JC polyomavirus viremia and progressive multifocal leukoencephalopathy in human leukocyte antigen-sensitized kidney transplant recipients desensitized with intravenous immunoglobulin and rituximab

BACKGROUND

Desensitization (DES) with intravenous immunoglobulin (IVIG) + rituximab is effective, safe, and increases the transplantation rate in human leukocyte antigen-sensitized patients. However, reports of progressive multifocal leukoencephalopathy (PML) caused by JC polyomavirus (JCPyV) in autoimmune patients treated with rituximab is concerning. Here, we report on the JCPyV viremia and PML status in kidney transplant patients with/without DES (non-DES).

METHODS

In total 1195 and 699 DNA samples from plasma in 117 DES (78% lymphocyte-depleting [LyD] induction) and 100 non-DES patients (45% LyD), respectively, were submitted for JCPyV-polymerase chain reaction. Results were compared in both groups.

RESULTS

No patients in either DES or non-DES developed PML or presented with any neurological symptoms. The JCPyV viremia rate was similar in DES and non-DES patients (3/117 vs. 9/100, P = 0.07). The JCPyV levels were low (median peak levels, 1025 copies/mL) and JCPyV viremia was observed only once during the study period in most patients. All 3 DES patients with JCPyV(+) received 1 dose rituximab and no DES patients with >1 dose rituximab showed JCPyV(+). All 3 JCPyV(+) DES patients received LyD induction, while only 2 of 9 JCPyV(+) non-DES patients did so, and the remaining 7 received non-LyD or no induction. JCPyV in leukocyte was mostly negative in DES and non-DES patients. Immunosuppression in patients with or without JCPyV(+) was similar. BK polyomavirus viremia was observed more commonly in patients with JCPyV(+) than in those without (P < 0.02).

CONCLUSIONS

Patients with IVIG + rituximab DES followed by transplantation with LyD induction and additional rituximab rarely show JCPyV viremia and appear at low risk for PML.

Liver Transplantation in a Patient With CD40 Ligand Deficiency and Hyper-IgM Syndrome: Clinical and Immunological Assessments

Monoclonal antibodies that disrupt CD40-CD40 ligand (CD40L) interactions are likely to have use in human transplantation. However, the extent of the immunosuppressive effects of CD40-CD40L blockade in humans is unknown. Hyper-IgM syndrome (HIGM) is a rare primary immunodeficiency syndrome characterized by defects in the CD40-CD40L pathway, severe immune deficiency (IgG), and high or normal IgM levels. However, the effects of CD40L deficiency on T- and natural killer (NK)-cell function is not established. Here, we present a patient with HIGM syndrome who underwent liver transplantation for hepatitis C virus infection. Posttransplantation, NK-cell antibody-dependent cytokine release (γ-interferon) to alloantigens and T cell responses to viral antigens and mitogens were assessed and showed normal CD4⁺ , CD8⁺ , and NK-cell responses. We also examined antibody-dependent cellular cytotoxicity against a CD40⁺ and HLA-expressing cell line. These experiments confirmed that the patient's NK cells were equivalent to those of normal subjects in mediating antibody-dependent cellular cytotoxicity despite the absence of CD40-CD40L interactions. Mitogenic stimulation of the patient's peripheral blood mononuclear cells showed no expression of CD40L on T and NK cells compared with increased expression in normal subjects. Taken together, these data suggest that absence of CD40L expression is responsible for aberrant B cell immunity but had little impact on NK- and T cell immune responses in vitro.

An update on the management and prevention of cytomegalovirus infection following allogeneic hematopoietic stem cell transplantation

ABSTRACT 

A significant progress has been made in deciphering critical aspects of the biology and immunology of CMV infection in the allogeneic stem cell transplantation setting. Genetic traits predisposing to active CMV infection and CMV end-organ disease have begun to be delineated. Reliable molecular assays for CMV DNA load quantitation in body fluids have been developed. Elucidation of immune mechanisms affording control of CMV infection will help to improve the management of active CMV infection. Finally, the advent of new CMV-specific antivirals and promising vaccine prototypes as well as the development of fine procedures for large-scale ex vivo generation of functional CMV-specific T cells for adoptive T cell transfer therapies will certainly minimize the negative impact of CMV on survival in these patients.

Issues in solid-organ transplantation in children: translational research from bench to bedside

In this review, we identify important challenges facing physicians responsible for renal and cardiac transplantation in children based on a review of the contemporary medical literature. Regarding pediatric renal transplantation, we discuss the challenge of antibody-mediated rejection, focusing on both acute and chronic antibody-mediated rejection. We review new diagnostic approaches to antibody-mediated rejection, such as panel-reactive antibodies, donor-specific cross-matching, antibody assays, risk assessment and diagnosis of antibody-mediated rejection, the pathology of antibody-mediated rejection, the issue of ABO incompatibility in renal transplantation, new therapies for antibody-mediated rejection, inhibiting of residual antibodies, the suppression or depletion of B-cells, genetic approaches to treating acute antibody-mediated rejection, and identifying future translational research directions in kidney transplantation in children. Regarding pediatric cardiac transplantation, we discuss the mechanisms of cardiac transplant rejection, including the role of endomyocardial biopsy in detecting graft rejection and the role of biomarkers in detecting cardiac graft rejection, including biomarkers of inflammation, cardiomyocyte injury, or stress. We review cardiac allograft vasculopathy. We also address the role of genetic analyses, including genome-wide association studies, gene expression profiling using entities such as AlloMap®, and adenosine triphosphate release as a measure of immune function using the Cylex® ImmuKnow™ cell function assay. Finally, we identify future translational research directions in heart transplantation in children.

Significant reduction of ATP production in PHA-activated CD4+ cells in 1-day-old blood from transplant patients

BACKGROUND

Global immunosuppression can be measured by assessing adenosine triphospate (ATP) levels in mitogen-stimulated CD4+ T cells.

METHODS

We investigated the effect of storage time on ATP levels in 234 blood samples from 18 healthy individuals and 152 transplant patients. The difference between day 0 (<13 hours post-blood draw) and day 1 (24-37 hours) measurements was analyzed and compared with various factors; a subset of samples was also analyzed in 6-hour intervals.

RESULTS

The ATP levels were significantly lower on day 1 compared with that on day 0 in healthy individuals (279±159 vs 414±159 ng/mL, P<0.001) and patients (356±209 vs 455±221 ng/mL, P<0.0001). Of the 18 healthy individuals, 17 showed ATP reduction, whereas 192 (89%) of 216 patients did so on day 1 (24.8±24.1%). In the time course analysis, ATP levels decreased with the blood storage time in healthy and patient samples, and the reduction began as early as 7 hours post-blood draw. The reduction rate was significantly higher in patient samples with low day 0 ATP levels compared with samples with moderate or high levels (44.7±31.3% vs 23.2±23.6% or 18.7±15.7%; P<0.001). The reduction rate in patients treated with alemtuzumab induction was slightly higher than that in daclizumab-treated patients (28.8±24.6% vs 21.3±21.3%, P=0.09). CD4+ cell number did not change within 24 hours post-blood draw, but CD4 expression decreased 2.0±2.8% (P<0.05).

CONCLUSIONS

The ATP levels are significantly lower in 1-day-old blood compared with fresh blood, suggesting that fresh blood should be used for assessing the T cell immune function to obtain the most accurate results.