Immune cell functional assay in monitoring of adult liver transplantation recipients with infection. Transplantation. 2010;89:620-626. [PMID: 20010326 DOI: 10.1097/tp.0b013e3181c690fa]

GRWR Correlates with the Metabolism of Tacrolimus after Pediatric Living Donor Liver Transplantation According to Donor CYP3A5 Polymorphism

Objectives. Tacrolimus is characterized by high pharmacokinetic variability in combination with a narrow therapeutic range. However, influence of donor CYP3A5 genotype and graft-to-recipient body weight ratio (GRWR) on tacrolimus’ pharmacokinetics after pediatric living donor liver transplantation (LDLT) remains unclear. Methods. A total of 174 LDLT recipients (<6 y) were grouped according to donor CYP3A5 genotypes (nonexpressor (NEX) or expressor (EX)) and GRWR (<3.0% (SS, small-size) or ≥3.0% (LS, large-size)): SS/NEX ( $n=40$ ), SS/EX ( $n=38$ ), LS/NEX ( $n=48$ ), and LS/EX ( $n=48$ ). Pharmacokinetics of tacrolimus and clinical outcomes were analyzed. Results. The relationships between the concentration-dose ratio and donor CYP3A5 genotypes and graft size were examined 3, 7, 14, and 30 days after the transplantation. Tacrolimus C0 levels varied greatly among groups, although recipients started with the same initial dosage. LS/EX recipients had significantly lower C0 levels in comparison with those of other groups. The use of CYP3A5-EX-grafts and a greater GRWR both resulted in significantly higher TAC dose requirements and lower C/D ratios. However, the significance of GRWR no longer exists 3 months after transplantation. The multivariate generalized linear mixed model analysis showed that donor CYP3A5 genotypes ( $F=11.876$ ; $P=0.01$ ) and GRWR ( $F=4.631$ ; $P=0.033$ ) were independent impact factors for C/D ratios 3, 7, 14, and 30 days after transplantation. Donor CYP3A5-EX genotype was associated with significantly increasing risks of infectious complications and significantly lower Cylex ATP values. However, no significant difference was observed in acute rejections among 4 groups. Conclusions. Monitoring of C0 levels alone is not reliable to guide tacrolimus administration. Donor CYP3A5 and GRWR both significantly affect tacrolimus pharmacokinetics after pediatric LDLT. The use of Cylex ATP tests would be helpful to avoid overimmunosuppression.

Prediction of Liver Transplant Rejection With a Biologically Relevant Gene Expression Signature

BACKGROUND

Noninvasive biomarkers distinguishing early immune activation before acute rejection (AR) could more objectively inform immunosuppression management in liver transplant recipients (LTRs). We previously reported a genomic profile distinguishing LTR with AR versus stable graft function. This current study includes key phenotypes with other causes of graft dysfunction and uses a novel random forest approach to augment the specificity of predicting and diagnosing AR.

METHODS

Gene expression results in LTRs with AR versus non-AR (combination of other causes of graft dysfunction and normal function) were analyzed from single and multicenter cohorts. A 70:30 approach (61 ARs; 162 non-ARs) was used for training and testing sets. Microarray data were normalized using a LT-specific vector.

RESULTS

Random forest modeling on the training set generated a 59-probe classifier distinguishing AR versus non-AR (area under the curve 0.83; accuracy 0.78, sensitivity 0.70, specificity 0.81, positive predictive value 0.54, negative predictive value [NPV] 0.89; F-score 0.61). Using a locked threshold, the classifier performed well on the testing set (accuracy 0.72, sensitivity 0.67, specificity 0.73, positive predictive value 0.48, NPV 0.86; F-score 0.56). Probability scores increased in samples preceding AR versus non-AR, when liver function tests were normal, and decreased following AR treatment (P < 0.001). Ingenuity pathway analysis of the genes revealed a high percentage related to immune responses and liver injury.

CONCLUSIONS

We have developed a blood-based biologically relevant biomarker that can be detected before AR-associated graft injury distinct from LTR never developing AR. Given its high NPV ("rule out AR"), the biomarker has the potential to inform precision-guided immunosuppression minimization in LTRs.

Joint Analysis of Microbial and Immune Cell Abundance in Liver Cancer Tissue Using a Gene Expression Profile Deconvolution Algorithm Combined With Foreign Read Remapping

Recent transcriptomics and metagenomics studies showed that tissue-infiltrating immune cells and bacteria interact with cancer cells to shape oncogenesis. This interaction and its effects remain to be elucidated. However, it is technically difficult to co-quantify immune cells and bacteria in their respective microenvironments. To address this challenge, we herein report the development of a complete a bioinformatics pipeline, which accurately estimates the number of infiltrating immune cells using a novel Particle Swarming Optimized Support Vector Regression (PSO-SVR) algorithm, and the number of infiltrating bacterial using foreign read remapping and the GRAMMy algorithm. It also performs systematic differential abundance analyses between tumor-normal pairs. We applied the pipeline to a collection of paired liver cancer tumor and normal samples, and we identified bacteria and immune cell species that were significantly different between tissues in terms of health status. Our analysis showed that this dual model of microbial and immune cell abundance had a better differentiation (84%) between healthy and diseased tissue. Caldatribacterium sp., Acidaminococcaceae sp., Planctopirus sp., Desulfobulbaceae sp.,Nocardia farcinica as well as regulatory T cells (Tregs), resting mast cells, monocytes, M2 macrophases, neutrophils were identified as significantly different (Mann Whitney Test, FDR< 0.05). Our open-source software is freely available from GitHub at https://github.com/gutmicrobes/PSO-SVR.git.

Predictive Value of Immune Cell Functional Assay for Non-Cytomegalovirus Infection in Lung Transplant Recipients: A Multicenter Prospective Observational Study

INTRODUCTION

Immune cell functional assay (ImmuKnow®) is a non-invasive method that measures the state of cellular immunity in immunosuppressed patients. We studied the prognostic value of the assay for predicting non-cytomegalovirus (CMV) infections in lung transplant recipients.

METHODS

A multicenter prospective observational study of 92 patients followed up from 6 to 12 months after transplantation was performed. Immune cell functional assay was carried out at 6, 8, 10, and 12 months.

RESULTS

Twenty-three patients (25%) developed 29 non-CMV infections between 6 and 12 months post-transplant. At 6 months, the immune response was moderate (ATP 225-525ng/mL) in 14 (15.2%) patients and low (ATP<225ng/mL) in 78 (84.8%); no patients had a strong response (ATP≥525ng/mL). Only 1 of 14 (7.1%) patients with a moderate response developed non-CMV infection in the following 6 months compared with 22 of 78 (28.2%) patients with low response, indicating sensitivity of 95.7%, specificity of 18.8%, positive predictive value (PPV) of 28.2%, and negative predictive value (NPV) of 92.9% (AUC 0.64; p=0.043). Similar acute rejection rates were recorded in patients with mean ATP≥225 vs. <225ng/mL during the study period (7.1% vs. 9.1%, p=0.81).

CONCLUSION

Although ImmuKnow® does not seem useful to predict non-CMV infection, it could identify patients with a very low risk and help us define a target for an optimal immunosuppression.

Immune cell function assays in the diagnosis of infection in pediatric liver transplantation: an open-labeled, two center prospective cohort study

BACKGROUND

Limited studies have been performed in assessment of immune status of pediatric liver transplants (PLTs). We conducted this study to evaluate Cylex immune cell function assay in diagnosis of infection and its potential clinical application in Chinese infant PLTs.

METHODS

In this prospective cohort study, 227 infant PLTs from two medical centers were enrolled, and 216 completed the study. Cylex ATP values were measured before and after liver transplantation (LT) at week 1, 2, 3, 4, 8, 12 and 24 respectively. Accordingly, patients' clinical records, including demographic data, liver function results, tacrolimus dosages and concentrations were collected and analyzed.

RESULTS

One hundred and sixty of 216 PLTs (74.1%) were diagnosed infection based on the parameters including abnormal vital signs, imaging changes, and pathogens detection, while 44 (20.4%) were clinically stable and 12 (5.6%) experienced acute rejection. The median Cylex ATP value in infant PLTs post-surgery reduced significantly in infection group compared to stable group (median, 137 vs. 269 ng/mL, P<0.001). Receiver operating characteristic (ROC) curve analysis determined that the cut-off value of Cylex ATP was 152 ng/mL in diagnosis of infection [area under the curve (AUC): 0.784, 95% CI: 0.720-0.848]. Meanwhile, Cylex ATP value showed no correlation to tacrolimus dosage, blood concentration, dose-normalized concentration/dose ratio or Kaup index. However, it tended to correlate weakly with the white blood cell (WBC) number (R =0.462, P<0.0001) and lymphocyte counts (R =0.363, P<0.0001).

CONCLUSIONS

In this study, we demonstrated that low Cylex ATP represented partly over-immunosuppression and had diagnostic value in infant PLTs with infections, which might assist individualized immunosuppression in PLT patients.

Predictive Value of Immune Cell Functional Assay for Non-Cytomegalovirus Infection in Lung Transplant Recipients: A Multicenter Prospective Observational Study

INTRODUCTION

Immune cell functional assay (ImmuKnow®) is a non-invasive method that measures the state of cellular immunity in immunosuppressed patients. We studied the prognostic value of the assay for predicting non-cytomegalovirus (CMV) infections in lung transplant recipients.

METHODS

A multicenter prospective observational study of 92 patients followed up from 6 to 12 months after transplantation was performed. Immune cell functional assay was carried out at 6, 8, 10, and 12 months.

RESULTS

Twenty-three patients (25%) developed 29 non-CMV infections between 6 and 12 months post-transplant. At 6 months, the immune response was moderate (ATP 225-525ng/mL) in 14 (15.2%) patients and low (ATP<225ng/mL) in 78 (84.8%); no patients had a strong response (ATP≥525ng/mL). Only 1 of 14 (7.1%) patients with a moderate response developed non-CMV infection in the following 6 months compared with 22 of 78 (28.2%) patients with low response, indicating sensitivity of 95.7%, specificity of 18.8%, positive predictive value (PPV) of 28.2%, and negative predictive value (NPV) of 92.9% (AUC 0.64; p=0.043). Similar acute rejection rates were recorded in patients with mean ATP≥225 vs. <225ng/mL during the study period (7.1% vs. 9.1%, p=0.81).

CONCLUSION

Although ImmuKnow® does not seem useful to predict non-CMV infection, it could identify patients with a very low risk and help us define a target for an optimal immunosuppression.

Discovery and validation of a novel blood-based molecular biomarker of rejection following liver transplantation

Noninvasive biomarker profiles of acute rejection (AR) could affect the management of liver transplant (LT) recipients. Peripheral blood was collected following LT for discovery (Northwestern University [NU]) and validation (National Institute of Allergy and Infectious Diseases Clinical Trials in Organ Transplantation [CTOT]-14 study). Blood gene profiling was paired with biopsies showing AR or ADNR (acute dysfunction no rejection) as well as stable graft function samples (Transplant eXcellent-TX). CTOT-14 subjects had serial collections prior to AR, ADNR, TX, and after AR treatment. NU cohort gene expression (46 AR, 45 TX) was analyzed using random forest models to generate a classifier training set (36 gene probe) distinguishing AR vs TX (area under the curve 0.92). The algorithm and threshold were locked and tested on the CTOT-14 validation cohort (14 AR, 50 TX), yielding an accuracy of 0.77, sensitivity 0.57, specificity 0.82, positive predictive value (PPV) 0.47, and negative predictive value (NPV) 0.87 for AR vs TX. The probability score line slopes were positive preceding AR, and negative preceding TX and non-AR (TX + ADNR) (P ≤ .001) and following AR treatment. In conclusion, we have developed a blood biomarker diagnostic for AR that can be detected prior to AR-associated graft injury as well a normal graft function (non-AR). Further studies are needed to evaluate its utility in precision-guided immunosuppression optimization following LT.

Monitoring cell-mediated immunity during immunosuppression reduction in heart transplant recipients with severe systemic infections

BACKGROUND

Treatment for severe systemic infections in heart transplantation is reduction in immunosuppression while treating the infection. An assay that measures adenosine triphosphate production in activated lymphocytes (ImmuKnow^® ) objectively monitors cellular immunity of transplant recipients. In this study, we used ImmuKnow^® to adjust immunosuppression in heart transplant recipients with severe systemic infections.

METHODS

Heart transplant recipients were followed with ImmuKnow^® at the time of biopsy and diagnosis of systemic infection. Patients who developed an infection were monitored by ImmuKnow^® assay with adjustments in immunosuppression based upon the results of the assay. Maintenance immunosuppression was reinstituted when the ImmuKnow^® increased to >225 ng/mL of ATP.

RESULTS

Two or more ImmuKnow^® assays were performed in 80 patients. Thirteen patients developed severe systemic infections. ImmuKnow^® mean value at the time of diagnosis of infection was 109 ± 49.2 ng/mL. Reduction in immunosuppression and treatment of infection resulted in normalization of ImmuKnow^® level, resolution of infection, and no episodes of rebound rejection.

CONCLUSION

Heart transplant recipients with severe systemic infections presented with a decreased ImmuKnow^® , suggesting over immunosuppression. ImmuKnow^® can be used as an objective measurement in withdrawing immunosuppression in heart transplant recipients with severe systemic infections.

Clinical relevance of a CD4+ T cell immune function assay in the diagnosis of infection in pediatric living-donor liver transplantation

The aim of the present study was to investigate the potential of the Immuknow immune cell function assay for the diagnosis of infection after pediatric living-donor liver transplantation (LDLT). Based on clinical data obtained following liver transplantation, 66 patients were divided into infection (n=28) and non-infection (n=38) groups. The following factors were considered in the present analysis: Primary disease, lymphocyte count, tacrolimus plasma concentration/dose (C0/D) ratio, CD4+ T lymphocyte ATP levels, at pre-transplant stage and at weeks 1-4, and 2 and 3 months post-transplant. The CD4+ T lymphocyte ATP values were plotted in a receiver operating characteristic (ROC) curve. The CD4+ T lymphocyte ATP value of the infection group was significantly lower compared with that of the non-infection group (188.6±93.5 vs. 424.4±198.1 ng/ml, respectively; P<0.05). No correlation was observed between the ATP value and tacrolimus plasma C0/D ratio (R2=0.0001484); however, a correlation was reported between the ATP value and lymphocyte count (R2=0.2149). Analysis of the ROC curve indicated that the ATP levels of CD4+ T cells were significantly associated with the diagnostic value of infection (area under the curve=0.866). These findings suggest that low CD4+ T lymphocyte ATP levels may be an independent risk factor for infection following pediatric LDLT, and that the Immuknow assay may be used as a tool to evaluate T lymphocyte function in such patients to predict the risk of infection.

Compliance with ethical standards in the reporting of donor sources and ethics review in peer-reviewed publications involving organ transplantation in China: a scoping review

OBJECTIVES

The objective of this study is to investigate whether papers reporting research on Chinese transplant recipients comply with international professional standards aimed at excluding publication of research that: (1) involves any biological material from executed prisoners; (2) lacks Institutional Review Board (IRB) approval and (3) lacks consent of donors.

DESIGN

Scoping review based on Arksey and O'Mallee's methodological framework.

DATA SOURCES

Medline, Scopus and Embase were searched from January 2000 to April 2017.

ELIGIBILITY CRITERIA

We included research papers published in peer-reviewed English-language journals reporting on outcomes of research involving recipients of transplanted hearts, livers or lungs in mainland China.

DATA EXTRACTION AND SYNTHESIS

Data were extracted by individual authors working independently following training and benchmarking. Descriptive statistics were compiled using Excel.

RESULTS

445 included studies reported on outcomes of 85 477 transplants. 412 (92.5%) failed to report whether or not organs were sourced from executed prisoners; and 439 (99%) failed to report that organ sources gave consent for transplantation. In contrast, 324 (73%) reported approval from an IRB. Of the papers claiming that no prisoners' organs were involved in the transplants, 19 of them involved 2688 transplants that took place prior to 2010, when there was no volunteer donor programme in China.

DISCUSSION

The transplant research community has failed to implement ethical standards banning publication of research using material from executed prisoners. As a result, a large body of unethical research now exists, raising issues of complicity and moral hazard to the extent that the transplant community uses and benefits from the results of this research. We call for retraction of this literature pending investigation of individual papers.

Delayed introduction of immunosuppressive regimens in critically ill patients after liver transplantation

BACKGROUND

The manipulation of immunosuppression therapy remains challenging in patients who develop infectious diseases or multiple organ dysfunction after liver transplantation. We evaluated the outcomes of delayed introduction of immunosuppression in the patients after liver transplantation under immune monitoring with ImmuKnow assay.

METHODS

From March 2009 to February 2014, 225 consecutive liver recipients in our institute were included. The delayed administration of immunosuppressive regimens was attempted in 11 liver recipients with multiple severe comorbidities.

RESULTS

The median duration of non-immunosuppression was 12 days (range 5-58). Due to the infectious complications, the serial ImmuKnow assay showed a significantly low ATP level of 64±35 ng/mL in the early period after transplantation. With the development of comorbidities, the ImmuKnow value significantly increased. However, the acute allograft rejection developed when a continuous distinct elevation of both ATP and glutamyltranspeptidase levels was detected. The average ATP level measured just before the development of acute rejection was 271±115 ng/mL.

CONCLUSIONS

The delayed introduction of immunosuppressive regimens is safe and effective in management of critically ill patients after liver transplantation. The serial ImmuKnow assay could provide a reliable depiction of the dynamics of functional immunity throughout the clinical course of a given patient.

Peripheral blood CD4(+) cell ATP activity measurement to predict HCC recurrence post-DCD liver transplant

BACKGROUND AND AIM

Hepatocellular carcinoma (HCC) recurrence after orthotopic liver transplantation (OLT) continues to confound transplant surgeons and physicians. There are no effective methods to predict the patients at risk for recurrence so far although many studies have sought meaningful biomarkers. The ImmuKnow (IMK) assay is an immune cell function assay that detects cell-mediated immunity in an immunosuppressed population, mainly measuring peripheral blood CD4(+) adenosine triphosphate (ATP) release. The aim of this study was to assess the relationship between cellular immune function measured by the ImmuKnow assay and HCC recurrence post-OLT.

METHODS

A total of 76 HCC cases underwent Donation after Cardiac Death (DCD) liver transplant, which confirmed hepatocellular carcinoma by histology postoperatively. The ImmuKnow assay was prospectively performed in these cases at a range of 6-36 months post-OLT. Every test was repeated 1 week later, obtaining the average value for every patient. In addition, every case had liver imaging findings at approximately the exam time.

RESULTS

Fifteen cases with liver imaging findings showed HCC recurrence (19.7%) post-OLT, and the average ImmuKnow assay in these patients was 190 ± 48 ng/ml, which was less (p < 0.05) than in patients without HCC recurrence, whose average ATP level was 313 ± 90 ng/ml. ATP levels post-OLT were found to be significantly associated with the risk of tumour recurrence. The ratio of T reg cells and the levels of TGFβ and IL-10 were higher in recurrence patients than in recurrence-free patients.

CONCLUSION

Greater suppression of cellular immunity, as measured by the ImmuKnow assay, was associated with progression of HCC recurrence post-OLT. ImmuKnow assay was helpful in determining the risk of early recurrence of HCC postliver transplant. A pathway consisting of T reg cells, TGFβ and IL-10 might be the HCC recurrence-predominant pathway.

Immunosuppression Modifications Based on an Immune Response Assay: Results of a Randomized, Controlled Trial

BACKGROUND

An immune function assay shows promise for identifying solid organ recipients at risk for infection or rejection. The following randomized prospective study was designed to assess the clinical benefits of adjusting immunosuppressive therapy in liver recipients based on immune function assay results.

METHODS

Adult liver recipients were randomized to standard practice (control group; n = 102) or serial immune function testing (interventional group; n = 100) performed with a commercially available in vitro diagnostic assay (ImmuKnow; Viracor-IBT Laboratories, Lee's Summit, MO) before transplantation, immediately after surgery and at day 1, weeks 1 to 4, 6, and 8, and months 3 to 6, 9, and 12. The assay was repeated within 7 days of suspected/confirmed rejection/infection and within 1 week after event resolution.

RESULTS

Based on immune function values, tacrolimus doses were reduced 25% when values were less than 130 ng/mL adenosine triphosphate (low immune cell response) and increased 25% when values were greater than 450 ng/mL adenosine triphosphate (strong immune cell response). The 1-year patient survival was significantly higher in the interventional arm (95% vs 82%; P < 0.01) and the incidence of infections longer than 14 days after transplantation was significantly lower among patients in the interventional arm (42.0% vs. 54.9%, P < 0.05). The difference in infection rates was because of lower bacterial (32% vs 46%; P < 0.05) and fungal infection (2% vs 11%; P < 0.05). Among recipients without adverse events, the study group had lower tacrolimus dosages and blood levels.

CONCLUSIONS

Immune function testing provided additional data which helped optimize immunosuppression and improve patient outcomes.

Evaluation of the immune function assay in pediatric living donor liver transplantation

The immune function (ImmuKnow) assay is a measure of cell-mediated immunity based on the peripheral CD4+ T cell ATP activity. The efficacy of ImmuKnow in pediatric LDLT is not well documented. The aim of this study was to assess the correlations between the ImmuKnow and the clinical status in pediatric LDLT recipients. A total of 716 blood samples were obtained from 60 pediatric LDLT recipients (one month to 16 yr of age). The recipient's status was classified as follows: stable, infection, or rejection. The ImmuKnow values in the pediatric LDLT recipients with a clinically stable status had a lower immune response (IQR 85-297 ATP ng/mL) than that previously reported in adults. Meanwhile, the ImmuKnow values of the stable patients were not correlated with age. Furthermore, a significant difference was found in the ImmuKnow values between the bacterial or fungal infection and stable groups, but not between the CMV or EBV infection and stable groups. The ImmuKnow levels in the pediatric LDLT were lower than those observed in the adult LDLT. The proposed reference value is between 85 and 297 ATP ng/mL in pediatric LDLT recipients. We conclude that the ImmuKnow assay could be helpful for monitoring pediatric LDLT recipients with bacterial or fungal infections.

The efficacy of the ImmuKnow assay for evaluating the immune status in human immunodeficiency virus and hepatitis C virus-coinfected patients

BACKGROUND

The survival of human immunodeficiency virus (HIV)-infected patients has significantly improved since the introduction of antiretroviral therapy (ART). However, the mortality due to hepatitis C virus (HCV)-related liver disease has not been reduced in HIV/HCV-coinfected patients, and HCV has recently become the most significant cause of death in HIV/HCV-coinfected patients. Liver transplantation might be one of the treatments of choice in such cases, but it is very difficult to evaluate the immune status of these patients due to ART, anti-HCV treatment, and HIV-related immunocompromised state.

AIM

The aim of this study was to evaluate the immune status in HIV/HCV-coinfected patients using the Cylex ImmuKnow assay, which was designed to monitor the global immune status by measuring the adenosine triphosphate (ATP) levels produced by activated CD4+ T cells.

METHODS

Twenty-eight HIV/HCV-coinfected patients were included in this study. We evaluated their immune activity using the ImmuKnow assay, and compared the data with those of HCV mono-infected patients indicated for liver transplantation as well as healthy controls.

RESULTS

The ATP levels of HIV/HCV-coinfected patients were significantly higher than those of HCV mono-infected liver transplant recipients (P < .001), and were significantly lower than those of healthy controls (P = .001).

CONCLUSION

The ImmuKnow assay was considered to be a useful tool to evaluate the immune status of HIV/HCV-coinfected patients.

CD4+ T-lymphocytes are activated by surgical stress following colorectal resection in cancer patients

The aim of the present study was to measure adenosine triphosphate (ATP) levels in CD4⁺ T cells as a marker of T-cell activity following surgery for colorectal cancer using the ImmuKnow assay kit. A total of 16 consecutive patients who underwent surgical resection for colorectal cancer between August and December, 2012 were enrolled in this study, of whom 7 underwent laparoscopic resection and 9 underwent open abdominal surgery. The intracellular ATP levels in CD4⁺ T-lymphocytes were measured using the ImmuKnow assay kit preoperatively and on the 1st, 4th and 8th postoperative days, as were the white blood cell (WBC) count, lymphocyte count and C-reactive protein (CRP) levels. The ATP level of the CD4⁺ T-cells was significantly elevated on the 1st day following surgery compared to the preoperative level (P<0.01) and gradually returned to preoperative levels; the lymphocyte count was significantly decreased on the 1st postoperative day (P<0.001). In addition, the ImmuKnow assay demonstrated that only the ATP level, but not the WBC count, lymphocyte count or CRP level, exhibited a significant difference on the 1st (P=0.080) and 8th (P=0.042) postoperative days between the laparoscopic and open abdominal surgery groups. In conclusion, the ATP level of CD4⁺ T-lymphocytes was increased in response to surgical stress, in tandem with a decrease in the lymphocyte count. Therefore, the ImmuKnow assay kit may be clinically applicable for monitoring the immune response following surgery, as it exhibits a higher sensitivity compared to other assays.

Personalized tacrolimus dose requirement by CYP3A5 but not ABCB1 or ACE genotyping in both recipient and donor after pediatric liver transplantation

Tacrolimus (TAC) is the backbone of an immunosuppressive drug used in most solid organ transplant recipients. A single nucleotide polymorphism (SNP) at position 6986G>A in CYP3A5 has been notably involved in the pharmacokinetic variability of TAC. It is hypothesized that CYP3A5 genotyping in patients may provide a guideline for TAC therapeutic regimen. To further evaluate the impact of CYP3A5 variants in donors and recipients, ABCB1 and ACE SNPs in recipients on TAC disposition, clinical and laboratory data were retrospectively reviewed from 90 pediatric patients with liver transplantation and their corresponding donors after 1 year of transplantation. The recipients with CYP3A5 *1/*1 or *1/*3 required more time to achieve TAC therapeutic range during the induction phase, and needed more upward dose during the late induction and the maintained phases, with lower C/D ratio, compared with those with CYP3A5 *3/*3. And donor CYP3A5 genotypes were found to impact on TAC trough concentrations after liver transplantation. No association between ABCB1 or ACE genotypes and TAC disposition post-transplantation was found. These results strongly suggest that CYP3A5 genotyping both in recipient and donor, not ABCB1 or ACE is necessary for establishing a personalized TAC dosage regimen in pediatric liver transplant patients.

Serial ImmuKnow assay in stable kidney transplant recipients

Objectives

The ImmuKnow assay (cylex Inc., Columbia, MD) has been reported to measure the global immune monitoring tool for organ transplantation recipients. We assess immuKnow ATP values in stable kidney transplant patients.

Material and methods

Patients who were kidney transplanted between September 2008 and May 2011 were enrolled in the prospective serial ImmuKnow assay study. The criteria of inclusion were living donor kidney transplantation (KT), no evidence of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection, and PRA less than 50%. ImmuKnow assay monitoring was performed at one day before operation, post operative weeks 4, 8, 12, 16, 20, 24, 36 and 52. We excluded patients who had undergone infectious syndrome or rejection episodes during the follow-up period.

Results

Among 71 patients who were enrolled in prospective serial ImmuKnow assay monitoring, 37 patients were proven to stable KT patients during the follow-up period. Two hundred and twenty-four samples from 37 patients were collected. ImmuKnow value and immunosuppression drug level were compared in post operative weeks 4, 8, 12, 16, 20, 24, 36 and 52. The value of ImmuKnow assay was significantly different depending on the length of time after transplant (p = 0.038). Interestingly, the pre-transplant ImmuKnow values were lower than those of the immediate post-transplant period.

Conclusions

The ImmuKnow value of stable KT recipients is different according to “time after transplant”. Therefore, “time after transplant” should be considered when applying an ImmuKnow assay in clinical practice.

Immune monitoring post liver transplant

Many of the causes of short and late morbidity following liver transplantation are associated with immunosuppression or immunosuppressive medications. Current care often involves close monitoring of liver biochemistry as well as therapeutic drug levels. However, the postoperative course following liver transplantation can often be associated with significant complications including infection and rejection, suggesting an inadequacy in current immune function monitoring. Many assays have been tested in the research setting to identify possible biomarkers that may be used to predict clinical events such as acute cellular rejection, and therefore allow modification of a patient’s immunosuppressive regimen prior to a clinical event. However, these generally require significant laboratory processing and have had difficulty becoming established in common clinical use outside the research setting. One assay, Cylex ImmuKnow has been food and drug administration approved but has had variable results. In this review we discuss the assays that have been used to assess monitoring of immune function after liver transplantation and consider possible future directions.

CYP3A5 genotypes affect tacrolimus pharmacokinetics and infectious complications in Chinese pediatric liver transplant patients

Little information is available regarding the impact of cytochrome P450 (CYP) 3A5 on the metabolism of TAC in infant LTx. Therefore, the CYP3A5 genotype of Chinese pediatric recipients (intestine) as well as donors (graft liver) was performed for the purpose of establishing an optimal dosage regimen in children. Sixty-four patients were divided according to CYP3A5 genotype (expression of *1 allele: EX and NEX) for each recipient (R) and donor (D), EX-R/EX-D (n = 21), EX-R/NEX-D (n = 8), NEX-R/EX-D (n = 8) and NEX-R/NEX-D (n = 27). Results indicated that initial TAC daily dose requirement was higher among EX-R/EX-D children compared with those who did not express CYP3A5 (0.28 ± 0.10 vs. 0.19 ± 0.08 mg/kg/day, p < 0.01). CYP3A5 expression contributed an overall of 38.35% to its C/D ratios, and graft liver was a key determinant. Additionally, the EX-R/EX-D group showed significantly higher incidence of infectious complications, lower immune response and was an independent risk factor for the development of infections (odds ratio 3.86, p = 0.025). Donor CYP3A5 expression partially explains TAC dose requirement, the effect of CYP3A5 variation may influence clinical outcomes; therefore, monitoring immune response may be important for preventing risks associated with under- and over-immunosuppression.

Clinical immune-monitoring strategies for predicting infection risk in solid organ transplantation

Infectious complications remain a leading cause of morbidity and mortality after solid organ transplantation (SOT), and largely depend on the net state of immunosuppression achieved with current regimens. Cytomegalovirus (CMV) is a major opportunistic viral pathogen in this setting. The application of strategies of immunological monitoring in SOT recipients would allow tailoring of immunosuppression and prophylaxis practices according to the individual's actual risk of infection. Immune monitoring may be pathogen-specific or nonspecific. Nonspecific immune monitoring may rely on either the quantification of peripheral blood biomarkers that reflect the status of a given arm of the immune response (serum immunoglobulins and complement factors, lymphocyte sub-populations, soluble form of CD30), or on the functional assessment of T-cell responsiveness (release of intracellular adenosine triphosphate following a mitogenic stimulus). In addition, various methods are currently available for monitoring pathogen-specific responses, such as CMV-specific T-cell-mediated immune response, based on interferon-γ release assays, intracellular cytokine staining or main histocompatibility complex-tetramer technology. This review summarizes the clinical evidence to date supporting the use of these approaches to the post-transplant immune status, as well as their potential limitations. Intervention studies based on validated strategies for immune monitoring still need to be performed.

Utility of an immune cell function assay to differentiate rejection from infectious enteritis in pediatric intestinal transplant recipients

The Cylex Immune Cell Function Assay measures cell-mediated immunity based on ATP production by stimulated CD4 + cells. We hypothesized that this test would discriminate acute cellular rejection (ACR) from infectious enteritis (IE) in pediatric intestinal transplant (ITx) recipients with allograft dysfunction. We retrospectively analyzed 224 Cylex assays drawn in 47 children who received 53 ITx. Samples were classified as stable, ACR, or IE based on clinical status. ATP values were analyzed using Kruskal-Wallis and t-tests. Overall, there was a statistically significant difference in ATP values based on clinical status (p = 0.03); however, overlap was observed between groups. The median ATP value during ACR was significantly greater than during stable periods (p = 0.02). No difference was seen in IE vs. stability (p = 0.8). The difference in median ATP value in ACR vs. IE approached significance (p = 0.1). Relative to previous levels, ACR episodes were associated with a median ATP increase of 101 ng/mL and IE episodes with a decrease of 3 ng/mL (p = 0.3). These data indicate that the Cylex assay has limited utility in differentiating ACR from IE, largely due to interpatient variability. Following longitudinal intrapatient trends may be an adjunctive tool in discriminating IE from ACR and guiding immunosuppression adjustments in select patients.

Increased intracellular adenosine triphosphate level as an index to predict acute rejection in kidney transplant recipients

BACKGROUND

Peripheral blood CD4+ T cell adenosine triphosphate (ATP) release has been reported to be an adjunct tool to evaluate global cellular immune response in solid-organ transplant recipients. However, the correlation between the ATP level and rejection was controversial. The aim of this prospective clinical study was to explore the association between the intracellular ATP level and the occurrence, progression, and treatment of acute rejection (AR) episodes, determine the predicting value of intracellular ATP level for AR in kidney transplant (KT) recipients.

PATIENTS AND METHODS

In the period of October 2011 to October 2012, 140 KT recipients were recruited and followed for six months after transplantation. Patients were categorized into stable group and AR group according to their clinical course. Whole blood samples were collected pretransplantation, and at 7, 14, 21, and 28days, and at 2, 3, 4, 5 and 6months post-transplantation. Additional blood samples were obtained from AR patients on the day AR occurred, on the day before and 3 and 7days after intravenous anti-rejection therapy started, and on the day when AR reversed. The intracellular ATP in CD4+ T cells was detected by ImmuKnow Immune Cell Function Assay according to the manufacturer's instruction. The absolute number of CD4+ T cells and the trough levels of tacrolimus and cyclosporine were also measured.

RESULTS

The ATP level detected on the day AR occurred (627.07±149.85ng/ml) was obviously higher than that of the stable group (320.48±149.11ng/ml, P<0.05). ATP value decreased to 265.35±84.33ng/m at the end of anti-rejection therapy, which was obviously lower than that measured on the day before the anti-rejection therapy started (665.87±162.85ng/ml, P<0.05). ROC analysis revealed that increased intracellular adenosine triphosphate level showed better sensitivity and specificity than those obtained using single time point detection (89.5% vs 85.0%;95.0% vs 88.9%). The best cutoff value was 172.55ng/ml. A positive correlation between the intracellular ATP level and absolute CD4+ T cell number (r=0.656, P<0.001) was found in the patients with CD4+ T cell counts <200/μl.

Current status of immunosuppression in liver transplantation

With advancements in immunosuppressive strategies and availability of better immunosuppressive agents, survival rate following liver transplantation has improved significantly in the recent times. Besides improvements in surgical techniques, the most important factor that has contributed to this better outcome is the progress made in the field of immunosuppression. Over the last several years, the trend has changed to tailored immunosuppression with the aim of achieving optimal graft function while avoiding its undesirable side effects. Induction agents are no longer used routinely and the aim is to provide minimal immunosuppression in the maintenance phase. The present review discusses the various types of immunosuppressive agents, their mechanism of action, clinical utility, advantages and disadvantages, and their side effects in short and long-term. It also discusses about tailoring immunosuppression in presence of various situations such as renal dysfunction, metabolic syndrome, hepatitis C recurrence, cytomegalovirus infections and so on. The issue of chronic kidney disease and the available renal sparing immunosuppressive strategies has been particularly stressed upon. Finally, it discusses about the practical aspects of various immunosuppression regimens including drug monitoring.

Immune function assay (ImmuKnow) as a predictor of allograft rejection and infection in kidney transplantation

BACKGROUND

The Cylex ImmuKnow (IK) assay provides a rapid and quantitative assessment of T-cell-mediated immune function. Studies have shown correlations between ImmuKnow assay and adverse events, such as immunosuppression and low or high calcineurin inhibitor trough levels. We investigated the correlation between IK changes and rejection or infection in kidney transplant patients and studied the potential application of the IK assays in optimizing individual immunosuppressive therapy.

METHODS

ImmuKnow assay was used to determine dynamic intracellular ATP changes in CD4 cells in 193 samples from 42 kidney transplant patients and 25 healthy subjects. Patients were categorized into rejection, infection, and event-free groups. The IK values were assayed and analyzed between kidney transplant patients and healthy controls.

RESULTS

Most IK values fell between 200 and 599 ng/mL from pre-transplantation to 30 months post-transplantation. The mean IK values continuously increased throughout 30 months. Incidental allograft rejection patients had significantly higher IK values compared with the event-free patients and controls. However, infection patients had significantly lower IK values. Seven days after treatment, IK values in rejection/infection patients were different compared with the values in autograft patients, and there was a significant correlation between calcineurin inhibitor (FK506) trough levels and IK values in rejection/infection patients. Serum creatinine levels in the rejection patients were significantly higher than those in the event-free patients, and C-reactive protein levels were significantly higher in the infection patients compared with the event-free patients.

CONCLUSIONS

The IK assay combined with other biomarkers can be used to identify kidney transplant patients at high risk of rejection and infection.

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.

Immunomodulating options for liver transplant patients

Much has changed since the early years of liver transplantation. Improvements in post-transplant survival are largely due to more selective and less toxic immunosuppression regimens and advances in operative and perioperative care. This has allowed liver transplantation to become an extremely successful treatment option for patients with endstage liver disease. Beginning with cyclosporine, a cyclic endecapeptide of fungal origin and the first of the calcineurin inhibitors to find widespread use, immunosuppressive regimens have evolved to include additional calcineurin inhibitors, steroids, mTOR inhibitors, antimetabolites and antibodies, mostly targeting T-cell activation. This review will present currently available immunosuppressive agents used in the perioperative period of liver transplantation, as well as maintenance treatments, tailoring therapeutic strategies for specific populations, and advances in immune monitoring and tolerance.

Use of the ImmuKnow assay to evaluate the effect of alemtuzumab-depleting induction therapy on cell-mediated immune function after renal transplantation

BACKGROUND

Good outcomes after renal transplantation are dependent on effective immunosuppression while minimizing infection. Alemtuzumab (Campath or Campath-1H) is an anti-CD52 humanized monoclonal IgG1 antibody which induces rapid and sustained depletion of circulating lymphocytes and has been effectively used as an immunosuppressant in post-transplant induction therapy.

METHODS

We used the ImmuKnow assay to compare cell-mediated immune function in renal transplant patients treated with alemtuzumab or with conventional immunosuppressive tri-therapy. The ImmuKnow method determines the levels of adenosine triphosphate (ATP) released from CD4 cells following stimulation with a mitogen.

RESULTS

We showed a statistically significant difference in the distribution of outcome after transplantation between the conventional and the Campath groups (P = 0.010). A significantly higher number of patients treated with alemtuzumab induction therapy were stable after transplantation compared to those treated with conventional immunosuppressive tri-therapy (96.6 vs. 75.7 %). ATP values were significantly higher in the conventional group compared to the Campath group at 180 days after transplantation (P < 0.001). ATP levels did not change significantly over time in clinically stable kidney recipients treated with alemtuzumab induction therapy (P = 0.554).

CONCLUSIONS

The ImmuKnow assay is a useful tool for evaluating the global immune response in alemtuzumab-treated renal transplant patients. Alemtuzumab-depleting induction therapy remains effective for at least 180 days.

ImmuKnow as a diagnostic tool for predicting infection and acute rejection in adult liver transplant recipients: a systematic review and meta-analysis

Immune status monitoring of transplant recipients could identify patients at risk of acute rejection, infection, and cancer, which are important sources of morbidity and mortality in these patients. The ImmuKnow assay provides an objective assessment of the cellular immune function of immunosuppressed patients. Inconclusive results concerning the ability of the ImmuKnow test to predict acute rejection and infection have raised concerns about the predictive value of ImmuKnow in liver transplant recipients. We conducted a systematic literature review to identify studies published up to March 2012 that documented the use of ImmuKnow for monitoring immune function in liver transplant recipients. The study quality was assessed with the Quality Assessment of Diagnostic Accuracy Studies 2 score. We identified 5 studies analyzing ImmuKnow performance for infection and 5 studies analyzing ImmuKnow performance for acute rejection. The pooled sensitivity, specificity, positive likelihood ratio, diagnostic odds ratio, and area under the summary receiver operating characteristic curve were 83.8% [95% confidence interval (CI) = 78.5%-88.3%], 75.3% (95% CI = 70.9%-79.4%), 3.3 (95% CI = 2.8-4.0), 14.6 (95% CI = 9.6-22.3), and 0.824 ± 0.034, respectively, for infection and 65.6% (95% CI = 55.0%-75.1%), 80.4% (95% CI = 76.4%-83.9%), 3.4 (95% CI = 2.4-4.7), 8.8 (95% CI = 3.1-24.8), and 0.835 ± 0.060, respectively, for acute rejection. Heterogeneity was low for infection studies and high for acute rejection studies. In conclusion, the ImmuKnow test is a valid tool for determining the risk of further infection in adult liver transplant recipients. Significant heterogeneity across studies precludes the conclusion that ImmuKnow identifies liver transplant patients at risk for rejection.

Can immune function assay predict infection or recovery?

BACKGROUND

Recently, the ImmuKnow assay (Cylex Inc., Columbia, Md) has been reported to be a global immune monitoring tool for organ transplants recipients. We assessed whether immunKnow ATP values predicted infectious syndromes.

METHODS

We prospectively enrolled 71 kidney transplant patients between September 2008 and May 2011. lmmuKnow assay monitoring was performed at one dav before as well as 4, 8, 12, 16, 20, 24, 36, and 52 weeks after the operation. ImmuKnow assay values were compared as well as BK viral infection pre-infection(PI), at first detection of infectious syndrome (DI), 4 weeks there after (4W), 8 weeks there after (8W) and 12 weeks there after (12W) and pre-recovery (PR), recovery (R) times.

RESULTS

Serial ImmuKnow assays showed significant differences over time and BK viral infectious state (P = .026). Interestingly, PI was significantly lower than DI and PR but PR significant greater than PI, 8W and 12W. However, we did not observe an adequate or absolute cutoff value of ImmuKnow by ROC curve: 377 ng/mL ImmuKnow showed 0.471 of AUC and 57.1% and 56.2%, of sensitivity and specificity.

CONCLUSION

Longitudinal evaluation and adjustment of the value of ImmuKnow assay seemed to be a favorable modality to monitor infectious syndromes especially those involving BK virus.

Machine learning analysis of the relationship between changes in immunological parameters and changes in resistance to Listeria monocytogenes: a new approach for risk assessment and systems immunology

No method has been reported to predict, even approximately, the impact of mild-to-moderate changes in several immunological parameters on resistance to infection. The ability to make such predictions would be useful in risk assessment. In addition, equations that predict host resistance on the basis of changes in components of a complex biological system (the immune system) would fulfill one of the major goals of systems biology. In this study, multiple machine learning classification methods were used to predict the effects of a series of drugs and chemicals on host resistance to Listeria monocytogenes in mice on the basis of changes in several holistic immunological parameters. A data set produced under the sponsorship of the National Toxicology Program (NTP) was used in this study. The NTP data set was found to have a high percentage of missing data and to be noisy (probably due to the intrinsically stochastic nature of immune responses). Data preprocessing steps were used to mitigate these problems. In evaluating the machine learning classifiers, we first randomly partitioned the NTP data set into 10 subsets. Each time, we used nine subsets of the data to train the machine learning classifiers, and the remaining single subset to predict outcomes with regard to host resistance. This process was repeated until all 10 combinations of the 9-1 split of the subsets have been tested. The best of the classifiers predicted host resistance outcome correctly for 94.7% of cases, a result which indicates it is possible to identify mathematical expressions that will be useful for risk assessment and to establish a basis for systems immunology.

Intracellular ATP production in CD4+ T cells as a predictor for infection and allograft rejection in trough-level guided pediatric liver transplant recipients under calcineurin-inhibitor therapy

BACKGROUND

The assessment of cell-mediated immune responses through the measurement of intracellular adenosine-tri-phosphate (iATP) production (Cylex ImmuKnow) as a pharmacodynamic biomarker of immune function represents a potential tool to optimize individual immunosuppressive therapy independent of drug dosage or trough levels. This study aims to investigate the correlations between iATP and adverse events, immunosuppression, calcineurin-inhibitor-trough levels, and age.

METHODS

In this prospective trial, 31 nontransplant pediatric subjects and 50 consecutive children were included after they underwent liver transplantation (LTX). During the study period, 4 allograft rejections and 3 acute infections occurred. The patients were treated with cyclosporine, tacrolimus, mycophenolate mofetil, and everolimus either as monotherapy or in combinations. The reactivity of the immune system was measured as iATP concentration in CD4+ T-cells after in vitro stimulation by phytohemagglutinin.

RESULTS

The iATP concentrations in patients with intercurrent, clinically significant infections were in the low immune response range (median iATP 181 versus 251 ng/mL, P = 0.308), whereas the patients with incidental allograft rejection had significantly higher iATP concentrations as compared with the event-free group (median iATP 444 versus 251 ng/mL, P = 0.017). However, there was a wide range of iATP concentrations in both nontransplant and LTX patient groups, and no clear iATP cut-off values for an increased risk of infection or rejection could be defined. Post LTX, stable-phase patients showed a significantly lower iATP compared with respective controls (median iATP 297 versus 384 ng/mL, P = 0.013). No significant correlation between calcineurin-inhibitor-trough concentrations and iATP was found. iATP was not correlated with age, but was inversely correlated with time after transplantation.

CONCLUSIONS

The observed correlation between clinical events and iATP concentrations is similar to the findings previously reported in adult patients who underwent transplantation. The lack of correlation of iATP with trough drug concentrations suggests that the ImmuKnow assay provides independent information that may be useful to guide immunosuppressive therapy in pediatric (liver) transplant patients. However, the wide range of iATP levels in event-free patients suggests that serial iATP measurements will be necessary to assess and guide the individual immunosuppressive therapy. Further investigations are needed to evaluate and extend these findings.

Can immune cell function assay identify patients at risk of infection or rejection? A meta-analysis

BACKGROUND

The Cylex ImmuKnow cell function assay (CICFA) is being considered as a possible tool for identification of infection and rejection in transplant recipients. However, the predictive capability of CICFA is still unclear.

METHODS

Herein, we performed a meta-analysis to assess the efficacy of CICFA in identifying risks of infection and rejection posttransplantation. After a careful review of eligible studies, sensitivity, specificity, and other measures of the accuracy of CICFA were pooled. Summary receiver operating characteristic curves were used to represent the overall test performance.

RESULTS

Nine studies met the inclusion criteria. The pooled estimates for CICFA in identification of infection risk were poor, with a sensitivity of 0.58 (95% confidence interval [CI]: 0.52-0.64), a specificity of 0.69 (95% CI: 0.66-0.70), a positive likelihood ratio of 2.37 (95% CI: 1.90-2.94), a negative likelihood ratio of 0.39 (95% CI: 0.16-0.70), and a diagnostic odds ratio of 7.41 (95% CI: 3.36-16.34). The pooled estimates for CICFA in identifying risk of rejection were also fairly poor with a sensitivity of 0.43 (95% CI: 0.34-0.52), a specificity of 0.75 (95% CI: 0.72-0.78), a positive likelihood ratio of 1.30 (95% CI: 0.74-2.28), a negative likelihood ratio of 0.96 (95% CI: 0.85-1.07), and a diagnostic odds ratio of 1.19 (95% CI: 0.65-2.20).

CONCLUSION

The current evidence suggests that CICFA is not able to identify individuals at risk of infection or rejection. Additional studies are still needed to clarify the usefulness of this test for identifying risks of infection and rejection in transplant recipients.

Assessing immunologic function through CD4 T-lymphocyte ahenosine triphosphate levels by ImmuKnow assay in Chinese patients following renal transplantation

OBJECTIVE

Balancing immunosuppression to prevent rejection while minimizing infection/drug toxicity risk is a challenge in organ transplantation. Drug monitoring alone or with functional monitoring is inadequate to measure the immune response after transplantation. The Food and Drug Administration (FDA)-approved immune monitoring assay, ImmuKnow, offers an noninvasive method to assess the immune status of transplanted patients by measuring adenosine triphosphate (ATP) released from CD4 T cells. Herein, we have evaluated ATP levels reflecting the immune responses of Chinese kidney transplant recipients as a monitoring parameter to guide treatment after transplantation.

METHODS

From October 2008 to March 2010, we recruited 259 kidney transplant patients who were divided into four groups: stable (n = 174), postoperative infection (n = 32), postoperative rejection (n = 16), and high-dose corticosteroid treatment (n = 33). The ImmuKnow assay was performed to measure CD4 T-cell ATP levels. No prisoners or organs from prisoners were used in the study.

RESULTS

Receiver operating characteristics measurements indicated an ATP predictive range of 238 to 497 ng/mL to monitor immune responses after transplantation and immunosuppressive therapy. To identify patients with infection, we used a cutoff ATP value of 238 ng/mL with 100% specificity and positive predictive value and 92.9% sensitivity. To identify patients with rejection, we used a value of 497 ng/mL with 91.5% sensitivity. Compared with the 225 to 525 ng/mL ATP levels recommended by the FDA, our target values showed similar or better diagnostic accuracy.

CONCLUSION

We provide additional data to monitor immunosupressant treatment of Chinese kidney transplant patients.

Lack of association of immune cell function test with rejection in kidney transplantation

BACKGROUND

The Cylex Immuknow assay provides a rapid assessment of global immune function in immunocompromised patients by measuring the global immune responses of CD4 T cells from a whole-blood sample. It may help to monitor the immune status of immunosuppressed transplant patients. However, earlier studies have shown that there is no consensus on the utility of the Immuknow assay in renal transplant rejection.

METHODS

T-cell activation was determined by measuring an increase of intracellular adenosine triphosphate (iATP) from CD4 cells in 227 samples from 116 kidney transplant patients. The results were analyzed regarding patient clinical status, namely, rejection, infection, or stability. In addition, we measured the immunologic response of 108 healthy control subjects.

RESULTS

There were 24 infectious and 36 rejection episodes. iATP concentrations differed significantly between stable and infected patients (180.5 ± 55.2 vs 375.3 ± 140.1 ng/mL; P < .001) and between infected patients and control subjects (180.5 ± 55.2 vs 436.5 ± 112 ng/mL; P < .001). No correlation was observed between patients suffering an acute rejection episode with this response.

CONCLUSIONS

Our results confirmed that the Immuknow assay identified transplant patients at risk for infection. It may provide information to guide immunosuppressive therapy, but the assay did not seem to have the potential to differentiate subjects experiencing rejection.

Trends in immune function assay (ImmuKnow; Cylex™) results in the first year post-transplant and relationship to BK virus infection

BACKGROUND

The ImmuKnow assay is a functional T-cell assay (TCA) that may quantify cellular immune responsiveness following renal transplantation. Using a standard protocol of TCA sampling in the first year post-transplant, we examined changes in TCA values over time and tested for an association between TCA and BK virus (BKV) infection as a marker of over-immunosuppression.

METHODS

We performed a single-center retrospective analysis of 897 TCA results in 414 renal transplant recipients obtained at 0 (N = 122), 1 (N = 316), 6 (N = 258) and 12 (N = 201) months post-transplant from May 2005 to July 2009 with concurrent urine and blood BKV polymerase chain reaction measurements.

RESULTS

Nearly 40% of patients experienced a decrease in TCA of >150 ng/mL from 1 to 6 months (mean 466-356 ng/mL, P < 0.0001) and remained stable from 6 to 12 months (mean 357 versus 370 ng/mL, P = 0.33). Neither a change in TCA of >150 ng/mL nor a TCA value of ≤ 225 ng/mL were associated with a diagnosis of BKV infection at 1 or 6 months, while TCA ≤ 225 ng/mL was associated with BKV infection at 12 months (P = 0.005).

CONCLUSIONS

A reduction in TCA from 1 to 6 months post-transplant is common and is not associated with conditions of over-immunosuppression, rendering the interpretation of changes in TCA during this time period difficult. BKV infection is associated with low TCA values at 12 months, suggesting that patients with low TCA values after 6 months may benefit from potential tailoring of immunosuppression or more aggressive monitoring to prevent subsequent BKV infection.

Invasive fungal infection after liver transplantation: risk factors and significance of immune cell function monitoring

OBJECTIVE

Monitoring immune status in transplant recipients is essential for predicting the risk of infections. The aims of the study were to identify the correlation of a low ImmuKnow adenosine triphosphate (ATP) value with the development of invasive fungal infections (IFIs) and whether this is an independent risk factor for IFIs in liver recipients.

METHODS

We followed up 248 liver recipients who developed 157 infectious episodes. Peripheral CD4(+) T cells were selected freshly for ATP detection. Percentages of T-helper (Th, CD3(+) CD4(+) ) and T-suppressor (Ts, CD3(+) CD8(+) ) lymphocyte subgroups were also examined.

RESULTS

Overall 44 patients (17.7%) were diagnosed as IFIs, of whom 9 (20.5%) died. The average ImmuKnow ATP value in the IFI patients (109 ± 78 ng/mL) was significantly lower than that in common bacterial infections (174 ± 106 ng/mL, P < 0.01) or stable liver recipients (314 ± 132 ng/mL, P < 0.01), while there was no difference in the Th/Ts ratio among each group. Logistic regression analysis showed ImmuKnow ATP value less than 100 ng/mL was an independent risk factor of IFI (OR = 3.44, P = 0.0237). ImmuKnow ATP values had no correlation with lymphocytes or their subgroups, but tended to correlate with the number of neutrophils and total white blood cells.

CONCLUSIONS

ImmuKnow assay monitoring has the potential to identify the patients at risk of developing IFI after liver transplantation (LT), which may provide a feasible measure for optimizing liver recipients' immune cellular function after transplantation.

Next level of immunosuppression: drug/immune monitoring

1. Current immunological monitoring relies heavily on clinical judgment and therapeutic drug levels and does not adequately assess the functional or donor-specific immunosuppression (IS) status of recipients of liver transplantation (LT). 2. Trough levels of drugs are arbitrary and are more clinically relevant for preventing supratherapeutic or subtherapeutic dosing and blood concentrations and for more closely monitoring at-risk populations (children, the elderly, and patients with organ dysfunction). The AUC or the post-dose levels may be more precise, but they have not been used extensively by transplant centers. 3. Data on drug/immune monitoring specific to LT are fairly limited; therefore, clinical practice is often borrowed from experiences with nonhepatic transplantation (mainly renal transplantation). 4. The monitoring of drug levels in patients taking generic immunosuppressants is challenging because the formulations may change with each prescription. The monitoring of drug or antibody levels is not yet clinically available for biological therapies (induction, lymphocyte-depleting, and maintenance agents). 5. Polymorphisms in drug metabolism (cytochrome P450 and P-glycoprotein) may be useful in selecting the initial and maintenance dosages of immunosuppressants and in preventing complications from over or underimmunosuppression. 6. Future immune monitoring assays should be focused on genomic or immunological predispositions and on specific reactivities to donor antigens to guide the appropriate dosing and minimization of IS after LT.

An immune function assay predicts post-transplant recurrence in patients with hepatocellular carcinoma

PURPOSE

An immune function assay has been proposed as a new strategy to monitor immunosuppression after organ transplantation. However, there are limited data regarding its role in liver transplant recipients with hepatocellular carcinoma (HCC). In this study, we sought to determine the utility of this functional assay in assessing the risk of infection, rejection, and tumor recurrence in liver transplant recipients.

METHODS

Immune function was determined by ImmuKnow assay that measures the amount of adenosine triphosphate (ATP) produced by CD4 (+) T cells to monitor the global immune status in 342 whole blood samples from 105 liver transplant recipients. The association between ATP value and post-transplant tumor recurrence was evaluated in 60 HCC patients. The ATP value in predicting tumor recurrence in other independent cohort of 92 recipients with HCC was analyzed prospectively.

RESULTS

The mean ATP values of liver transplant recipients with infection (145.2 ± 87.0 ng/ml) or acute rejection (418.9 ± 169.5 ng/ml) were different from those with stable state (286.6 ± 143.9 ng/ml, P < 0.05). In recipients with HCC who developed recurrent tumors, the values were significantly lower than those without recurrence (137.8 ± 66.4 vs. 289 ± 133.9 ng/ml, P < 0.01); the optimal threshold value to predict post-transplant tumor recurrence was 175 ng/ml. Comparing with the patients in lower immune group (ATP ≤ 175 ng/ml), patients in the higher immune group (ATP > 175 ng/ml) experienced significantly better disease-free survival (P < 0.01). Multivariate Cox regression analysis showed the ATP value was an independent predictor of HCC recurrence.

CONCLUSIONS

The immune function assay has the potential to assess the risk of infection and rejection in liver transplantation and to predict post-transplant tumor recurrence in recipients with HCC.

The relationship between adenosine triphosphate within CD4(+) T lymphocytes and acute rejection after liver transplantation

BACKGROUND

There have been increasing interests in the relationship between CD4(+) T lymphocytes and acute rejection (AR) in transplantation. In this study, we explore the role of CD4(+) T lymphocytes after liver transplantation.

METHODS

  From February to October 2009, 87 patients underwent liver transplantation. They were divided into the AR group and non-acute rejection (NAR) group, with 56 healthy individuals in the control group. Blood specimens were collected preoperatively and at one, two, and four wk postoperatively for all groups and also on the day when AR occurred and one wk after intravenous glucocorticoid therapy for the AR group. Adenosine triphosphate (ATP) levels were measured using the ImmuKnow™ test kits for immune cell functions.

RESULTS

  After transplantation, the ATP levels within CD4(+) T lymphocytes were significantly elevated in the two groups when compared with the preoperative levels. It peaked in the AR group and was significantly higher than that of the NAR group (p < 0.05). By ROC curve analysis, the obvious elevation of the ATP value one wk after transplantation had better sensitivity and specificity in diagnosing the AR. The ATP sensitivity rate for early AR was 85.7% and specificity rate 80.9% when the cutoff value was 407 μg/L. The ATP value collected on the day of AR occurrence has apparently positive correlation with the rejection acting index (RAI) (p < 0.01). After the intravenous glucocorticoid therapy, all the ARs were reversed and the ATP value declined significantly compared with the control group and that on the day when AR occurred (p < 0.01).

CONCLUSIONS

  During the early postoperative period (especially at first week after liver transplantation), the elevation of ATP levels within CD4(+) T lymphocytes has good sensitivity and specificity in diagnosing the AR at early stage. And the degree of AR has positive relationship with ATP value. After the intravenous glucocorticoid therapy, the obvious declination of AR might be used in evaluating the effectiveness of anti-rejection treatment.

Screening of mortality in transplant patients using an assay for immune function

BACKGROUND

So far, the ImmuKnow Immune Cell Function Assay (Cylex, Inc., Columbia, MD, USA) has been used to assess risks of infection and rejection in transplant patients. We hypothesized that the ImmuKnow assay might be used for mortality screening in transplant patients overall.

METHODS

In the period of February 2007 to December 2009, at the Uppsala University Hospital, 362 patients who received either kidney, kidney+pancreas, kidney+islet cells, liver or liver+kidney allografts were randomly screened using the ImmuKnow assay. All causes of mortality were compared between two groups: patients with at least one ImmuKnow assay below 175ng/mL and patients with all ImmuKnow assays from 175ng/mL and above. Subsequently, the frequency of rejection within thirty days of the ImmuKnow assay was compared between these two groups.

RESULTS

The study included 1031 ImmuKnow assays obtained from the 362 patients. A total of 111 patients had at least one ImmuKnow below 175ng/mL and 251 patients had all their ImmuKnow assays from 175ng/mL and above. By January 31st 2010, 16 of 111 patients (14.4%) with at least one ImmuKnow assay below 175ng/mL were deceased, compared to 13 of 251 patients (5.2%) with all ImmuKnow assays from 175ng/mL and above (p=0.0053, Fisher's exact test). There was no difference in the frequency of rejection between the two groups (19.8% versus 17.5%, p=0.66).

CONCLUSIONS

In addition to assessing relative risks of infection and rejection in transplant patients, the ImmuKnow assay may be used to identify patients with increased risk of short-term mortality. Transplant patients being highly overimmunosuppressed as assessed by the ImmuKnow assay do not seem to have a lower risk of short-term rejection.