Assessing relative risks of infection and rejection: a meta-analysis using an immune function assay

Pretransplant donor-specific and non-specific immune parameters associated with early acute rejection

BACKGROUND

New immunosuppression protocols have resulted in decreased rates of biopsy-proven acute rejection; however, it is unclear whether recipients without biopsy-proven acute rejection are still at risk for immune complication and chronic allograft dysfunction. The aim of our studies was to determine whether pretransplant immune parameters were associated with posttransplant early acute rejection, unstable creatinine courses, and poor graft outcome.

METHODS

Immune parameters, including human leukocyte antigen (HLA) mismatch, HLA-specific antibodies, global CD4+ cellular response as measured by intracellular adenosine triphosphate (iATP) synthesis, and IFN-gamma precursor frequencies to donor or third-party cells as measured by ELISPOT were determined for a total of 126 kidney recipients treated with a protocol, including rapid discontinuation of prednisone.

RESULTS

The donor specific pretransplant parameters of HLA class I mismatches (P=0.04) and total HLA mismatches (P=0.04) with the donor as well as the pretransplant HLA-donor specific antibodies (P=0.002) were associated with biopsy-proven acute rejection. Higher pretransplant iATP levels, a donor nonspecific parameter, were found associated with biopsy proven acute rejection (P=0.04). Pretransplant iATP levels were significantly greater for recipients with early unstable creatinine levels (P=0.01). Recipients with a pretransplant iATP value greater than 375 ng/ml were 3.67 times more likely to experience acute rejection (P=0.03).

CONCLUSIONS

Pretransplant assessment of donor specific and nonspecific immune parameters may identify recipients who can benefit from closer clinical and immunological surveillance to allow for tailored immunsuppression and selective intervention aimed at optimizing both short and long-term graft outcome.

Intracellular ATP concentrations of CD4 cells in kidney transplant patients with and without infection

In the field of organ transplantation, overimmunosuppression is associated with severe side effects, such as infection, drug toxicity, and cancer, whereas underimmunosuppression is associated with acute rejection. Intracellular adenosine triphosphate (iATP) concentration following CD4 cell activation provides an assessment of cellular immune function to help monitor the immune status of immunosuppressed patients. This assay has shown to be the first post-transplant test related not only to the risk of acute rejection but also with the appearance of infection. The aim of our study was to compare the iATP concentrations of CD4 cells between healthy adults and kidney transplant recipients from a European population, analyzing the differences according to transplant clinical status. Samples from 81 kidney transplant patients who were admitted to our hospital over a nine-month period were drawn. T-cell activation was measured by determining the increase of iATP from CD4 cells. Results were compared with patient clinical status (rejection, infection, and stability). Three patients suffered an acute rejection episode and they were not included in the analysis (mean iATP concentration 247 +/- 87 ng/mL). iATP concentrations differed significantly between stable and infected patients (313 +/- 193 vs. 197 +/- 114 ng/mL; p = 0.008). iATP concentration values were not related to the length of admission, age, peak and current panel reactive antibodies, mismatches, leukocytes, weight, creatinine, days after transplantation and blood levels of cyclosporin, tacrolimus, and sirolimus. This assay measures global immune responses of CD4 T cells from a whole-blood sample, allowing for the assessment of the impact of immuno- suppressive drugs and of the patient's underlying clinical conditions. This assay identifies transplant patients at risk for infection or rejection, providing information which can guide immunosuppressive therapy.

Treatment of intestinal failure: intestinal transplantation

Over the past 15 years, intestinal transplantation for the treatment of intestinal failure has changed from a desperate last-ditch effort into a standard therapy for which a good outcome is expected. Patient survival after intestinal transplantation has improved in the past 3-5 years and now approaches that of other solid organ allograft recipients, including liver and kidney, and is similar to survival on permanent therapy with parenteral nutrition. Complications are more common and often more severe during the initial hospitalization period after intestinal transplantation than they are after transplantation of other solid organs. After intestinal transplantation the initial hospitalization period is, therefore, usually 3-8 weeks long. Nearly all patients discharged after intestinal transplantation have good allograft function and have been weaned from total parenteral nutrition. The cost of the initial hospitalization period is one to two times the cost of permanent total parenteral nutrition for 1 year, which means that, in most cases, intestinal transplantation is cost-saving within 2 years of transplantation. In addition, quality of life after intestinal transplantation, as determined by standardized quality of life measures, is good or normal.

Diagnostic Tools for Monitoring Kidney Transplant Recipients

Recent advancements in immunobiology have introduced several new diagnostic tools for monitoring kidney transplant recipients. These have been added to more established tests that, although imperfect, remain important benchmarks of diagnostic utility. Both new and old tests can be characterized with regard to their practicality, and as to whether they detect aberrant function or define the cause of dysfunction. Unfortunately, no current test is both practical and specific to a particular disease entity. Accordingly, the diagnosis of graft dysfunction remains dependent on the proper use and interpretation of many studies. This article reviews the current assays that have been evaluated in the clinic for the diagnosis of renal allograft-related diseases. These are limited to assays based on routinely obtainable samples such as blood, biopsy tissue, and urine. Newer studies are presented, along with more mundane assays, to highlight the practical use of studies regardless of their degree of mechanistic sophistication.

Options for immunologic support of renal transplantation through the HLA and immunology laboratories

HLA and immunology laboratories are an integral part of clinical kidney transplant programs. They assist transplant clinicians with evaluating the immunological suitability of potential recipients for transplantation and selecting donor-recipient combinations with a low risk of immunological failure. With sophisticated new techniques becoming available for posttransplant immunological monitoring, laboratories play an increasing supporting role during posttransplant follow up. The level of precision at which immunological testing predicts clinical outcome, however, leaves room for improvement. In this article, we summarize the current state of diagnostics, discuss problems, and point out promising developments.

Posttransplant monitoring of pediatric lung transplant recipients

PURPOSE OF REVIEW

This article reviews current trends in pediatric lung posttransplant management, reveals pitfalls that exist, and introduces additional parameters that may have an impact on long-term survival.

RECENT FINDINGS

A number of parameters are monitored after transplantation to prevent or identify early complications related to lung transplantation in hope of reducing morbidity and mortality. These include routine laboratory studies, imaging, and monitoring of drug levels and lung function. Drug monitoring allows individualization of a patient's immunosuppressive therapy; however, drug levels alone may not reflect the patient's immune status. ImmuKnow is a general immune-monitoring assay that may help guide therapy. Two major complications are rejection and infection, and bronchoscopy is used to differentiate these two entities. Silent rejection may occur and increase the chance of developing bronchiolitis obliterans; therefore, many centers perform surveillance bronchoscopies. Recently, de-novo anti-histocompatibility locus antigen antibodies and gastroesophageal reflux have been associated with poor outcomes, and many centers are monitoring these entities as part of care following lung transplant.

SUMMARY

There has been little improvement in long-term outcomes of lung transplantation. Current monitoring methods are utilized to maintain or improve outcomes and recently additional monitoring parameters have been identified which hopefully will improve long-term outcomes.

Preceeding the rejection: in search for a comprehensive post-transplant immune monitoring platform

The survival of a transplanted organ is dependent on maintenance of continuous immunosuppression. However, even the strictest adherence to the recommended drug levels does not prevent the occurrence of numerous complications associated with immunosuppression. The efficacy of immunosuppression therapy protocols would be enhanced greatly by the availability of biotechnologies capable of identifying and predicting immunological events prior to the manifestation of clinical parameters indicating graft failure. The aim of the study was to evaluate the potential contribution of some modern tools for post-transplantation monitoring, and to propose a method for combining them into a comprehensive mechanism for this purpose. The technologies utilized in this study are among a group of 'cutting edge' diagnostic methods at the initial steps of evaluation for their potential contribution for post-transplantation immune monitoring. This study was a pioneering opportunity to combine and utilize these tools jointly. The method of research was based on monitoring 13 adult kidney transplant recipients. The Immuknow assay determined cellular immunity status by quantitative measurement of intracellular ATP level in CD4(+) lymphocytes after PHA stimulation. Sera were analyzed for concentration of soluble CD30 reflecting primary allo-stimulation and for donor specific anti-HLA antibodies responsible for accelerated and refractory rejection. The results were correlated with clinical and pathological parameters and appraisal of predictive value was attempted. In Immuknow assay analysis ATP incremental changes indicative of rejection or infection were found in 75% and in 50% incidences, respectively. In stable patients, the ATP deviation from the preoperative baseline, indicative of stable engraftment, was much less pronounced than in other habitual clinical tests. CD30 concentrations were measured greatly above normal values prior to biopsy-proven rejection episodes, both before and after the transplant operation. Anti-HLA antibodies were elevated at a later stage, concurrently with clinical manifestation of graft failure and rejection. Anti-HLA antibody level remained negligible in patients going through a stable post-transplant clinical course. Overall, the utilization of the platform of combined biotechnologies could serve as a valuable tool for immune monitoring in organ transplantation, allowing for therapeutic intervention that can favorably affect the clinical outcome.

Developing a tool for noninvasive monitoring of renal allografts

Renal transplantation has emerged as the therapy of choice for many patients with end-stage renal disease. One of the major goals is to tailor immunosuppressive therapy to the individual needs of every patient at every time point post transplant, balancing the risk for rejection and over-immunosuppression. Such individualized treatment will require assays that can detect harmful processes in the allograft early and that can be measured repeatedly. In this review, advantages and disadvantages of current assays to monitor renal allografts noninvasively and how proteomic technology might contribute to the development of novel biomarkers to improve patient management will be discussed.