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

Kidney transplantation in the elderly

Interest in kidney transplant studies in the elderly population is increasing as more research has been conducted on the immune system. With this review, we hope to encourage the need for research on kidney transplantation in the elderly.

Relationship between immune function recovery and infectious complications in patients following living donor liver transplantation

AIM

The ImmuKnow (IK) assay enables the evaluation of peripheral blood CD4(+) adenosine triphosphate activity to facilitate an objective assessment of the cellular immune function in immunosuppressed patients. However, it is unclear whether the IK assay is utilized during the acute postoperative periods following living donor liver transplantation (LDLT).

METHODS

The IK values of 43 LDLT recipients were measured during the month following LDLT to evaluate the relationship between the measured IK values and infectious events.

RESULTS

The IK values after LDLT were significantly increased compared with the IK values before LDLT ( P < 0.01). During the month following transplantation, the rate of bacterial infection in the recipients with IK values of more than 225 ng/mL was significantly lower than that in the recipients with IK values of 225 ng/mL or less ( 42.1% vs 91.7%, respectively; P < 0.01). The rate of severe infections among the recipients who maintained IK values of more than 150 ng/mL was significantly lower than that among the recipients with IK values of 150 ng/mL or less during the month following transplantation ( 3.7% vs 56.3%, respectively; P < 0.01).

CONCLUSION

The immune system of LDLT recipients dramatically improved following transplantation. The IK values of LDLT recipients were associated with the incidence of infectious events during the perioperative period after LDLT. Monitoring IK values was useful during both the acute and long-term postoperative periods.

A Rationale for Age-Adapted Immunosuppression in Organ Transplantation

Demographic changes are associated with a steady increase of older patients with end-stage organ failure in need for transplantation. As a result, the majority of transplant recipients are currently older than 50 years, and organs from elderly donors are more frequently used. Nevertheless, the benefit of transplantation in older patients is well recognized, whereas the most frequent causes of death among older recipients are potentially linked to side effects of their immunosuppressants.Immunosenescence is a physiological part of aging linked to higher rates of diabetes, bacterial infections, and malignancies representing the major causes of death in older patients. These age-related changes impact older transplant candidates and may have significant implications for an age-adapted immunosuppression. For instance, immunosenescence is linked to lower rates of acute rejections in older recipients, whereas the engraftment of older organs has been associated with higher rejection rates. Moreover, new-onset diabetes mellitus after transplantation is more frequent in the elderly, potentially related to corticosteroids, calcineurin inhibitors, and mechanistic target of rapamycin inhibitors.This review presents current knowledge for an age-adapted immunosuppression based on both, experimental and clinical studies in and beyond transplantation. Recommendations of maintenance and induction therapy may help to improve graft function and to design future clinical trials in the elderly.

Immune cell function assay does not identify biopsy-proven pediatric renal allograft rejection or infection

Management of pediatric renal transplant patients involves multifactorial monitoring modalities to ensure allograft survival and prevent opportunistic infection secondary to immunosuppression. An ICFA, which utilizes CD4 T-cell production of ATP to assess immune system status, has been used to monitor transplant recipients and predict susceptibility of patients to rejection or infection. However, the validity of this assay to reflect immune status remains unanswered. In a two-yr retrospective study that included 31 pediatric renal transplant recipients, 42 patient blood samples were analyzed for immune cell function levels, creatinine, WBC (white blood cell) count, immunosuppressive drug levels, and viremia, concurrent with renal biopsy. T-cell ATP production as assessed by ICFA levels did not correlate with allograft rejection or with the presence or absence of viremia. ICFA levels did not correlate with serum creatinine or immunosuppressive drug levels, but did correlate with WBC count. The ICFA is unreliable in its ability to reflect immune system status in pediatric renal transplantation. Further investigation is necessary to develop methods that will accurately predict susceptibility of pediatric renal transplant recipients to allograft rejection and infection.

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.

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.

Comparison of several functional methods to evaluate the immune response on stable kidney transplant patients

The introduction of new immunosuppressive drugs in the last two decades has been associated with a significant decline in the prevalence of acute rejection and a huge improvement of graft survival. Monitoring blood levels of immunosuppressive drugs is the most common way to control drug doses in renal transplant patients. This approach is useful and widely used but doesn't give accurate information about the immune status of the patient. For this goal, there are many "in house" protocols which give more information, but cannot be standardized, limiting their applicability to compare results between different laboratories. In this study we compare three classical functional methods to evaluate the immune response: Mixed lymphocyte reaction (MLR), phytohemagglutinin stimulated peripheral blood lymphocytes (PBLs), and anti-CD3 monoclonal antibodies (mAbs) against PBL with the only FDA-labeled assay to measure the patient immune status: Cylex ImmuKnow® that measures the intracelullar ATP in CD4+ lymphocytes. We used n=111 stable renal transplant patients, all the patients with more than one year functioning grafts. We referred the results to a control population of healthy blood donors (n=125).

RESULTS

Measurement of intracellular ATP in CD4+ lymphocytes is able to differentiate immunosuppressed populations in renal transplant patients from health controls (242.30±21.62 vs. 386.43±25.12, p 0.0001). By contrary, there were no differences between controls and renal recipients when functional response was measured by MLR, PHA and anti-CD3 mAbs (2.48±0.45 vs. 2.37±0.41; 2.84±0.76 vs. 2.37±0.32; 2.32±0.34 vs. 1.89±0.38 respectively). In summary, our results show that the measurement of ATP in CD4+ lymphocytes gives more accurate information in comparison to the classical methods.

Report of the second joint meeting of ESOT and AST: current pipelines in biotech and pharma

Following the first joint meeting organized by the European (ESOT) and American (AST) Societies of Transplantation in 2010, a second joint meeting was held in Nice, France, on October 12-14, 2012 at the Palais de la Mediterannee. Co-chairs of the scientific advisory committee were Dr. Flavio Vincenti (AST) and Dr. Teun Van Gelder (ESOT). The goal was to discuss the key unmet needs in solid organ transplantation with the opportunity to interrelate current basic research efforts with clinical translation. Thus, the topic of this second meeting "Transformational therapies and diagnostics in transplantation" was devised and a summary of this meeting follows.

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.

Confronting the challenge: individualized immune monitoring after organ transplantation using the cellular immune function assay

The survival of a transplanted organ is dependent on avoidance of rejection, achieved through continuous immuno-suppression. Management of the transplant recipient confronts the clinician with a key challenge of post-transplant immune monitoring. Early detection of an activated allo-immune response is a harbinger of incipient rejection. Thus, timely intervention may prevent acute and chronic injury to the transplanted organ. Similarly, over immune-suppression can lead to infections or malignancies, hence the importance of early detection of the precarious suppression. The need for non-invasive systemic immune monitoring of the transplant recipient is therefore imperative. This review describes the cellular immune function assay--a non-invasive diagnostic method for evaluation of the net state of the recipient's cellular immune function. We describe the background that brought about the need for a reliable diagnostic tool for serial immune monitoring, and we overview the main mile-stones in the assimilation of the assay and its implementation in the clinic. The arising conclusion presents a novel non-invasive diagnostic bio-marker for post-transplant immune monitoring which enables the clinician to intervene prior to manifestation of clinical complications. The usefulness of the assay in detecting a state of over-suppression has been consensually described in multiple publications while its contribution in detection and management of under-suppression conditions remains to be determined by means of prospective interventional studies. The cellular immune function assay can be useful and beneficial for patient care only if used for longitudinal monitoring through serial testing.