Identification of patients at risk of acute rejection by pretransplantation and posttransplantation monitoring of soluble CD30 levels in kidney transplantation

Contemporary Biomarkers for Renal Transplantation: A Narrative Overview

Renal transplantation (RT) is the preferred treatment for end-stage renal disease. However, clinical challenges persist, i.e., early detection of graft dysfunction, timely identification of rejection episodes, personalization of immunosuppressive therapy, and prediction of long-term graft survival. Biomarkers have emerged as valuable tools to address these challenges and revolutionize RT patient care. Our review synthesizes the existing scientific literature to highlight promising biomarkers, their biological characteristics, and their potential roles in enhancing clinical decision-making and patient outcomes. Emerging non-invasive biomarkers seemingly provide valuable insights into the immunopathology of nephron injury and allograft rejection. Moreover, we analyzed biomarkers with intra-nephron specificities, i.e., glomerular vs. tubular (proximal vs. distal), which can localize an injury in different nephron areas. Additionally, this paper provides a comprehensive analysis of the potential clinical applications of biomarkers in the prediction, detection, differential diagnosis and assessment of post-RT non-surgical allograft complications. Lastly, we focus on the pursuit of immune tolerance biomarkers, which aims to reclassify transplant recipients based on immune risk thresholds, guide personalized immunosuppression strategies, and ultimately identify patients for whom immunosuppression may safely be reduced. Further research, validation, standardization, and prospective studies are necessary to fully harness the clinical utility of RT biomarkers and guide the development of targeted therapies.

Soluble CD30, the Immune Response, and Acute Rejection in Human Kidney Transplantation: A Systematic Review and Meta-Analysis

Soluble CD30 (sCD30) is considered to be a marker for the activated immune system in which T cells can damage the allograft. Some studies reported that post-transplant sCD30 can predict early acute rejection and can thereby be used as a biomarker to detect acute rejection. However, several other studies found no relation between post-transplant sCD30 and acute rejection. This meta-analysis study aims to answer this main question of whether sCD30 can help clinicians to monitor transplant recipients. The electronic databases, including PubMed, Web of Science, ProQuest, Embase, Scopus, Google Scholar, the gray literature, and the key journals, were searched for observational studies from 1 January 1990 up to 30 April 2018. Eighteen studies, with a total of 1,453 patients, were included in this paper. With regard to the different measurement times, post-transplant sCD30 was separately analyzed and divided into five groups (i.e., 1, 2, 3, 4 week, and 1 month post-transplant sCD30). All groups indicated a strong association between sCD30 and the acute rejection. The standardized mean difference (SMD) is 1.22 in 1 week, 0.77 in 2 week, 1.11 in 3 week, 1.27 in 4 week, and 0.71 in 1 month groups. The association between sCD30 and acute rejection was consistent across all the subgroup analyses. We found that post-transplant sCD30 had a strong association with acute kidney rejection. We also found that the deceased donors had more association with the high amount of sCD30 than living donors in patients with acute rejection. Finally, we realized that donor type was an important factor leading to the heterogeneous results in the primary studies.

Biomarkers in renal transplantation: An updated review

Genomics, proteomics and molecular biology lead to tremendous advances in all fields of medical sciences. Among these the finding of biomarkers as non invasive indicators of biologic processes represents a useful tool in the field of transplantation. In addition to define the principal characteristics of the biomarkers, this review will examine the biomarker usefulness in the different clinical phases following renal transplantation. Biomarkers of ischemia-reperfusion injury and of delayed graft function are extremely important for an early diagnosis of these complications and for optimizing the treatment. Biomarkers predicting or diagnosing acute rejection either cell-mediated or antibody-mediated allow a risk stratification of the recipient, a prompt diagnosis in an early phase when the histology is still unremarkable. The kidney solid organ response test detects renal transplant recipients at high risk for acute rejection with a very high sensitivity and is also able to make diagnosis of subclinical acute rejection. Other biomarkers are able to detect chronic allograft dysfunction in an early phase and to differentiate the true chronic rejection from other forms of chronic allograft nephropathies no immune related. Finally biomarkers recently discovered identify patients tolerant or almost tolerant. This fact allows to safely reduce or withdrawn the immunosuppressive therapy.

Increased Circulating T Lymphocytes Expressing HLA-DR in Kidney Transplant Recipients with Microcirculation Inflammation

We consecutively enrolled 82 kidney transplant recipients (KTRs) with stable renal function and 24 KTRs who underwent indication biopsy to compare the histological grading of renal allografts with the activity of circulating T lymphocyte subsets and monocytes determined by flow cytometry, which were obtained at 2 weeks after kidney transplantation (KT) and at the time of indication biopsy, respectively. The sum of the scores of glomerulitis (g) + peritubular capillaritis (ptc), inflammation (i) + tubulitis (t), interstitial fibrosis (ci) + tubular atrophy (ct), and fibrointimal thickening (cv) + arteriolar hyaline thickening (ah) was used to assign a histological grade to the renal allograft samples. The frequencies of CD4⁺HLA-DR⁺/CD4⁺ T cells and CD8⁺HLA-DR⁺/CD8⁺ T cells were significantly increased in KTRs with a microcirculation inflammation (MI) sum score ≥ 1 when compared with KTRs with an MI sum score = 0 as well as stable KTRs. In these 2 subsets, only CD4⁺HLA-DR⁺/CD4⁺ T cells were positively correlated with MI sum scores. Analysis using the receiver operating characteristic (ROC) curve showed that antibody-mediated rejection (AMR) could be predicted with a sensitivity of 80.0% and a specificity of 94.7%, using a cutoff value of 29.6% frequency of CD4⁺HLA-DR⁺/CD4⁺ T cells. MI was significantly associated with an increased frequency of activated T lymphocytes expressing human leukocyte antigen-antigen D related (HLA-DR). Further studies should focus on validating the utility of circulating CD4⁺HLA-DR⁺/CD4⁺ T cells as a noninvasive, immunologic monitoring tool for the prediction of AMR.

Barcelona Consensus on Biomarker-Based Immunosuppressive Drugs Management in Solid Organ Transplantation

With current treatment regimens, a relatively high proportion of transplant recipients experience underimmunosuppression or overimmunosuppression. Recently, several promising biomarkers have been identified for determining patient alloreactivity, which help in assessing the risk of rejection and personal response to the drug; others correlate with graft dysfunction and clinical outcome, offering a realistic opportunity for personalized immunosuppression. This consensus document aims to help tailor immunosuppression to the needs of the individual patient. It examines current knowledge on biomarkers associated with patient risk stratification and immunosuppression requirements that have been generally accepted as promising. It is based on a comprehensive review of the literature and the expert opinion of the Biomarker Working Group of the International Association of Therapeutic Drug Monitoring and Clinical Toxicology. The quality of evidence was systematically weighted, and the strength of recommendations was rated according to the GRADE system. Three types of biomarkers are discussed: (1) those associated with the risk of rejection (alloreactivity/tolerance), (2) those reflecting individual response to immunosuppressants, and (3) those associated with graft dysfunction. Analytical aspects of biomarker measurement and novel pharmacokinetic-pharmacodynamic models accessible to the transplant community are also addressed. Conventional pharmacokinetic biomarkers may be used in combination with those discussed in this article to achieve better outcomes and improve long-term graft survival. Our group of experts has made recommendations for the most appropriate analysis of a proposed panel of preliminary biomarkers, most of which are currently under clinical evaluation in ongoing multicentre clinical trials. A section of Next Steps was also included, in which the Expert Committee is committed to sharing this knowledge with the Transplant Community in the form of triennial updates.

High-dose immunosuppressant alters the immunological status of New Zealand white rabbits following skin transplantation

The aim of this study was to investigate the effect of an immunosuppressant on the immunological status of New Zealand white rabbits after skin grafting, and to evaluate a method for monitoring the immunological status of subjects with skin transplants. The rabbits were randomly divided into allograft rejection, autograft tolerance, nontransplant, allograft low-dose immunosuppressant and allograft high-dose immunosuppressant groups. The rabbits in the low- and high-dose immunosuppressant groups were treated with cyclosporine A intravenously 8 h prior to skin transplantation and once daily following transplantation at doses of 2 and 25 mg/kg, respectively. At 12 days after skin transplantation, the spleens of donor (female) rabbits and recipient (male) rabbits were harvested for the preparation of single-cell suspensions. The splenocytes from recipient and donor rabbits were labeled with 0.3 or 6 µM carboxy fluorescein diacetate succinimidyl ester, respectively, and a mixed cell suspension was prepared. The final preparation was intravenously injected into recipient New Zealand white rabbits. The ratio of the two fluorescently labeled cell populations in the peripheral blood was measured using flow cytometry at 1, 2, 4 and 8 h after the injection, and the cell death rate was calculated. Histological analysis was also performed on samples collected at the time of splenectomy. The cell death rates of the allograft rejection and low-dose immunosuppressant groups reached their highest levels 8 h after the injection of spleen cell suspension. Allogeneic spleen cells from donor male rabbits were almost completely removed within 8 h of injection. The cell death rate increased slowly in the nontransplant, autograft and high-dose immunosuppressant groups without specificity. This study provides a specific method for the in vivo monitoring of the immunological status of patients after skin grafting. This method can quickly and accurately detect the immunological status of recipients following the injection of a mixed splenocyte suspension, thereby indicating the strength of immune rejection by the immune systems of the recipients.

T-Cell Surface Antigens and sCD30 as Biomarkers of the Risk of Rejection in Solid Organ Transplantation

T-cell activation is a characteristic of organ rejection. T cells, located in the draining lymph nodes of the transplant recipient, are faced with non-self-molecules presented by antigen presenting cells and become activated. Activated T cells are characterized by up-regulated surface antigens, such as costimulatory molecules, adhesion molecules, chemokine receptors, and major histocompatibility complex class II molecules. Surface antigen expression can be followed by flow cytometry using monoclonal antibodies in either cell function assays using donor-specific or nonspecific stimulation of isolated cells or whole blood and without stimulation on circulating lymphocytes. Molecules such as CD30 can be proteolytically cleaved off the surface of activated cells in vivo, and the determination of the soluble protein (sCD30) in serum or plasma is performed by immunoassays. As promising biomarkers for rejection and long-term transplant outcome, CD28 (costimulatory receptor for CD80 and CD86), CD154 (CD40 ligand), and sCD30 (tumor necrosis factor receptor superfamily, member 8) have been identified. Whereas cell function assays are time-consuming laboratory-developed tests which are difficult to standardize, commercial assays are frequently available for soluble proteins. Therefore, more data from clinical trials have been published for sCD30 compared with the surface antigens on activated T cells. This short review summarizes the association between selected surface antigens and immunosuppression, and rejection in solid organ transplantation.

Biomarkers to assess donor-reactive T-cell responses in kidney transplant patients

Different to antibody-mediated rejection (ABMR), T-cell mediated rejection (TCMR) still unpredictably occurs after kidney transplantation in a great part because of a poor immunologic evaluation of the cellular allogeneic immune response. However, in the last years, important efforts have focused on the development of novel and more sensitive assays to monitor T-cell alloimmune responses at different biological levels that may improve the understanding of the functional status of the cellular immune compartment in patients undergoing organ transplantation. In this direction, immune assays evaluating T-cell proliferation, intracellular ATP release, multiparameter flow cytometry, profiling T-cell receptor repertoires and measurements of frequencies of cytokine-producing T-cells using an IFN-γ enzyme-linked immunospot assay (IFN-γ ELISPOT) have been reported showing interesting associations between the cellular alloimmune response and kidney transplant outcomes. In summary, an important progress has been made in the assessment of alloreactive T-cell responses in the context of organ transplantation using novel immune assays at different biological levels. However, there is an urgent need for prospective, randomized clinical studies to validate these encouraging preliminary data to ultimately introduce them in current clinical practice for refining current immune-risk stratification in kidney transplantation.

Post-transplant soluble CD30 levels are associated with early subclinical rejection in kidney transplantation

Several studies have shown association of high pre- or post-transplant levels of soluble CD30 (sCD30) with acute rejection and poor late kidney transplant outcome. Our goal was to investigate whether sCD30 levels at month-3 post-transplant are associated with subclinical rejection, presence of CD30(+) cells within the graft, and expression of immune response genes in peripheral blood mononuclear cells. The study comprised 118 adult first kidney graft recipients, transplanted at a single center, receiving tacrolimus in low concentration. All were submitted to a protocol biopsy at month-3. Subclinical rejection was identified in 10 biopsies and sCD30 levels ≥ 61.88 ng/mL (P = 0.004), younger recipient age (P = 0.030) and non-Caucasian ethnicity (P = 0.011) were independently associated with this outcome. Rare CD30(+) cells were present in only two biopsies. There was a correlation between sCD30 levels and CD30 gene expression in peripheral blood mononuclear cells (r = 0.385, P = 0.043). These results show that high sCD30 levels are independent predictors of graft dysfunction and may contribute to patient selection protocols by indicating those who could benefit from a more thorough evaluation.

Soluble CD30 does not predict late acute rejection or safe tapering of immunosuppression in renal transplantation

BACKGROUND

Previous reports revealed the potential value of the soluble CD30 level (sCD30) as biomarker for the risk of acute rejection and graft failure after renal transplantation, here we examined its use for the prediction of safe tapering of calcineurin inhibitors as well as late acute rejection.

METHODS

In a cohort of renal transplant patients receiving triple immunosuppressive therapy we examined whether sCD30 can be used as a marker for safe (rejection-free) discontinuation of tacrolimus at six months after transplantation (TDS cohort: 24 rejectors and 44 non-rejecting controls). Also, in a second cohort of patients (n=22, rejectors n=11 and non-rejectors n=11), participating in a clinical trial of rituximab as induction therapy after renal transplantation (RITS cohort), we examined whether sCD30 could predict the occurrence of late (>3months post-transplant) acute rejection episodes. sCD30 was measured by ELISA in serum taken before and at several time points after transplantation.

RESULTS

Overall, in the TDS cohort sCD30 decreased after transplantation. No difference in sCD30 was observed between rejectors and non-rejecting controls at any of the time points measured. In addition, in the RITS cohort, sCD30 measured at three months after transplantation were not indicative for the occurrence of late acute rejection.

CONCLUSION

In two prospectively followed cohorts of renal transplant patients we found no association between sCD30 and the occurrence of either late acute rejection or acute rejection after reduction of immunosuppression.

Association of high post-transplant soluble CD30 serum levels with chronic allograft nephropathy

The purpose of this study was to evaluate the association of post-transplant soluble CD30 (sCD30) levels, isolated or in combination with of anti-HLA class II antibodies and of serum creatinine levels, with kidney graft loss due to chronic allograft nephropathy (CAN), and type of lesions in graft biopsies for cause. The study comprised 511 first kidney graft recipients, transplanted at a single center, with a graft functioning for at least 2.8 years. A single blood sample was collected from each patient. sCD30 levels were determined by ELISA, and HLA antibodies by Luminex assay. The minimum follow-up after testing was 9.3 years. High sCD30 levels, set at sCD30 ≥ 34.15 ng/mL, the presence of HLA class II antibodies, and serum creatinine ≥ 1.9 mg/dL were independently associated with CAN-graft loss (P values <0.0001, 0.05, <0.0001, respectively), and the combined hazard ratio for CAN-graft loss was 20.2. Analyses of 166 biopsies for cause showed that high sCD30 levels and creatinine were independently associated with interstitial lesions. Post-transplant sCD30 serum levels, especially in conjunction with information regarding HLA class II antibodies and serum creatinine levels, provide valuable information regarding graft outcome and could be useful for the management of kidney transplant recipients.

Immunologic monitoring in kidney transplant recipients

Transplant biopsy has always been the gold standard for assessing the immune response to a kidney allograft (Chandraker A: Diagnostic techniques in the work-up of renal allograft dysfunction-an update. Curr Opin Nephrol Hypertens 8:723-728, 1999). A biopsy is not without risk and is unable to predict rejection and is only diagnostic once rejection has already occurred. However, in the past two decades, we have seen an expansion in assays that can potentially put an end to the "drug level" era, which until now has been one of the few tools available to clinicians for monitoring the immune response. A better understanding of the mechanisms of rejection and tolerance, and technological advances has led to the development of new noninvasive methods to monitor the immune response. In this article, we discuss these new methods and their potential uses in renal transplant recipients.

Peripheral blood sampling for the detection of allograft rejection: biomarker identification and validation

Currently, acute allograft rejection can only be detected reliably by deterioration of graft function confirmed by allograft biopsy. A huge drawback of this method of diagnosis is that substantial organ damage has already taken place at the time that rejection is diagnosed. Discovering and validating noninvasive biomarkers that predict acute rejection, and chronic allograft dysfunction, is of great importance. Many studies have investigated changes in the peripheral blood in an attempt to find biomarkers that reflect changes in the graft directly or indirectly. Herein, we will review the promises and limitations of the peripheral blood biomarkers that have been described in the literature so far.

Pretransplant soluble CD30 serum concentration does not affect kidney graft outcomes 3 years after transplantation

INTRODUCTION

An elevated serum concentration of soluble the form of CD30 (sCD30), an activation marker of mainly T(H)2-type cytokines producing T lymphocytes, has been reported as a predictive factor for acute cellular rejection episodes and poor graft outcomes in kidney transplantation. This historic cohort study investigated the association of a pretransplant sCD30 serum concentrations with kidney graft function and graft survival 3 years posttransplantation in adult recipients of deceased donor kidney grafts, treated with monoclonal anti-CD25 antibodies as an induction treatment combined with a cyclosporine (CsA)-based maintenance triple therapy.

MATERIALS AND METHODS

The pretransplant sera of 296 recipients were tested for sCD30 content using a microsphere flow-cytometry assay. The estimated glomerular filtration rate (eGFR) was determined by the 4-variable Modification of Diet in Renal Disease equation. The incidences of graft loss were calculated with the use of Kaplan-Meier survival analysis and compared using the log-rank test.

RESULTS

According to the distribution of the pretransplant sCD30 levels concentration ≥2700 pg/mL was defined as high (n = 146) and concentration <2700 pg/mL as low (n = 150). Three years posttransplantation, the eGFR was not significantly different in the recipients in high and low sCD30 groups (65 ± 24 vs 67 ± 21 mL/min/1.73 m(2); P = .43); there was no association between the eGFR 3 years after transplantation and the pretransplant sCD30 levels (r(2) = 0.002; P = .49). Graft survival 3 years after transplantation was also not different in the recipients in high and low sCD30 groups (P = .52).

CONCLUSION

In our adult deceased-donor kidney graft recipients, the pretransplant sCD30 serum concentration was not a predictive factor of immunologic risk associated with the kidney graft function 3 years posttransplantation; neither did it affect graft survival 3 years after transplantation. The immunosuppression with anti-CD25 antibodies as an induction treatment combined with the CsA-based maintenance triple therapy could possibly be decisive for our findings.

Soluble CD30: a serum marker for Epstein-Barr virus-associated lymphoproliferative diseases

The soluble form of CD30 (sCD30), a member of tumor necrosis factor receptor superfamily, has been used as a marker of disease activity in various lymphomas. Epstein-Barr virus (EBV) is a potent stimulator of CD30 expression. The study aims to evaluate whether sCD30 can be used as a diagnostic marker for EBV-associated infectious mononucleosis (IM) and post-transplant lymphoproliferative disease (PTLD). Plasma from EBV seropositive healthy controls (N = 90), acute IM patients (n = 90), non-PTLD heart/lung transplant recipients (N = 30) and EBV-positive PTLD patients (N = 23) was tested for sCD30 using a commercially available ELISA kit. EBV DNA was tested by real time quantitative polymerase chain reaction assay. Significantly higher sCD30 levels were observed in acute IM patients (median 242.9 ng/ml) compared to EBV seropositive controls (median 15.7 ng/ml; P < 0.0001). These levels were highest in IM patients within 14 days of onset of illness. PTLD patients had significantly higher sCD30 levels (median 94 ng/ml) than healthy controls (P < 0.0001) and transplant patients (median 27 ng/ml; P = 0.0007). EBV DNA was detected mostly in acute IM and PTLD patients. In both cases there was a significant correlation between sCD30 and EBV DNA levels in plasma (P < 0.0001). This study demonstrates that sCD30 and EBV DNA levels can be used as potential markers for diagnosis of IM and PTLD.

Review: Pharmacodynamic monitoring of immunosuppression in kidney transplantation

Advances in immunosuppressive therapies have improved kidney transplant outcomes. However, immunosuppressant drug-induced toxicities continue to reduce tolerability and impact patient and graft survival. A major ongoing challenge in kidney transplantation is to establish ways of tailoring immunosuppressant therapy so as to maintain efficacy while minimizing toxicity. Pharmacodynamic monitoring by direct measurement of immune cell function has the potential to personalize immunosuppression. The purpose of this review is to provide the clinician with an overview of the methodology and use of immune function monitoring in the field of kidney transplantation.

Noninvasive diagnosis of acute rejection of renal allografts

PURPOSE OF REVIEW

Acute rejection is an immune process that begins with the recognition of the allograft as nonself and ends in graft destruction. Histological features of the allograft biopsy are currently used for the differential diagnosis of allograft dysfunction. In view of the safety and the opportunity for repetitive sampling, development of noninvasive biomarkers of allograft status is an important objective in transplantation. Herein, we review some of the progress towards the development of noninvasive biomarkers of human allograft status.

RECENT FINDINGS

Urinary cell and peripheral blood cell mRNA profiles have been associated with acute rejection of human renal allografts. Emerging data support the idea that development of noninvasive biomarkers predictive of antibody-mediated rejection is feasible. The demonstration that intragraft microRNA expression predicts renal allograft status suggests that noninvasively ascertained microRNA profiles may be of value.

SUMMARY

We are pleased with the progress to date, and anticipate clinical trials investigating the hypotheses that noninvasively ascertained mRNA profiles will minimize the need for invasive biopsy procedures, predict the development of acute rejection and chronic allograft nephropathy, facilitate preemptive therapy capable of preserving graft function, and facilitate personalization of immunosuppressive therapy for the allograft recipient.

TH1/TH2 cytokines and soluble CD30 levels in kidney allograft patients with donor bone marrow cell infusion

OBJECTIVE

We investigated the relevance of donor bone marrow cell infusion (DBMI) and serum levels of interferon-gamma (IFN-gamma), interleukin-10 (IL-10), and soluble CD30 (sCD30) in kidney recipients.

PATIENTS AND METHODS

We analyzed the allograft outcomes correlated with sCD30, IFN-gamma, and IL-10 levels using pre- and posttransplantation sera from 40 live donor renal transplants (20 patients with DBMI [2.1 x 10(9) +/- 1.3 x 10(9) mononuclear cells/body] and 20 controls).

RESULTS

Patients with acute rejection episodes (ARE)-3/20 DBMI and 6/20 controls-showed increased sCD30 and IFN-gamma as well as decreased IL-10 posttransplantation compared with nonrejectors. Significant differences were observed for sCD30 and IFN-gamma levels: 59.54 vs 30.92 ng/mL (P = .02) and 11.91 vs 3.01 pg/mL (P = .01), respectively. Comparison of pre- and posttransplant levels of IFN-gamma, IL-10, and sCD30 in ARE patients showed higher levels in posttransplant sera except for IFN-gamma in controls (6.37 vs 11.93; P = .01). Increased IFN-gamma and IL-10 were correlated with rejection (r = .93; P = .008). sCD30 correlated with serum creatinine among ARE patients in control and DBMI groups (r = .89; P = .019; and r = 1.00; P < .0001, respectively).

CONCLUSIONS

Higher levels of sCD30, IFN-gamma, and IL-10 posttransplantation in rejecting patients provided evidence for coexistence of cellular and humoral responses in ARE. There appeared to be a down-regulatory effect of infusion on alloresponses.

Association between serum soluble CD30 and serum creatinine before and after renal transplantation

OBJECTIVE

There is increasing evidence that circulating levels of soluble CD30 (sCD30) may represent a biomarker for outcome in kidney transplantation. The aim of this study was to measure the pre- and posttransplantation serum levels of sCD30 in cadaveric kidney transplant recipients and correlate them with serum creatinine.

PATIENTS AND METHODS

Serum sCD30 was measured by a commercial enzyme-linked immunosorbent assay (ELISA) from prospective samples of 38 kidney allograft recipients serially transplanted at our center. Samples were collected at day 0 pretransplantation and at months 6, 12, 18, and 24 posttransplantation. We also studied sera from 29 patients with chronic kidney disease (CKD) at different stages of the K/DOQI guidelines, as a control group.

RESULTS

Serum levels of sCD30 decreased significantly in samples posttransplantation compared with pretransplantation. The significant decrease after transplantation may be related to the improvement in renal function since we observed a significant correlation between serum levels of sCD30 and creatinine (sCr) at all times of the study. In addition, the patients with chronic renal failure showed a significant association between serum sCD30 and sCr (r = .454; P = .013).

CONCLUSIONS

Our results did not suggest that the measurement of sCD30 may be used as a valuable biomarker in renal transplantation. Increased levels may be related to a decrease in its renal elimination.

Can immune monitoring help to minimize immunosuppression in kidney transplantation?

The serious side-effects and complications related to the life-long use of immunosuppressors in transplantation have fuelled research into their possible minimization or even complete elimination. The field of transplantation is therefore tentatively moving from a phase of empiric immunosuppression towards individualized therapy. This process is highly dependent on the development of immune monitoring tests to detect an individual 'level of risk'. Immune monitoring is a way of measuring functional and molecular correlates of immune reactivity to provide clinically useful information for therapeutic decision-making. The technological breakthroughs over the last decade provide firm grounds for the achievement of this goal. Large, multicentric and prospective studies in the near future are now crucial if these tests are to achieve the necessary approval from the regulatory authorities and promptly enter the clinic for routine use.

Maternal serum soluble CD30 is increased in normal pregnancy, but decreased in preeclampsia and small for gestational age pregnancies

OBJECTIVE

Women with preeclampsia and those who deliver small for gestational age (SGA) neonates are characterized by intravascular inflammation (T helper 1 (Th1)-biased immune response). There is controversy about the T helper 2 (Th2) response in preeclampsia and SGA. CD30, a member of the tumor necrosis factor receptor superfamily, is preferentially expressed in vitro and in vivo by activated T cells producing Th2-type cytokines. Its soluble form (sCD30) has been proposed to be an index of Th2 immune response. The objective of this study was to determine whether the maternal serum concentration of sCD30 changes with normal pregnancy, as well as in mothers with preeclampsia and those who deliver SGA neonates.

METHODS

This cross-sectional study included patients in the following groups: (1) non-pregnant women (N = 49); (2) patients with a normal pregnancy (N = 89); (3) patients with preeclampsia (N = 100); and (4) patients who delivered an SGA neonate (N = 78). Maternal serum concentration of sCD30 was measured by a specific and sensitive enzyme-linked immunoassay. Non-parametric tests with post-hoc analysis were used for comparisons. A p value <0.05 was considered statistically significant.

RESULTS

(1) The median sCD30 serum concentration of pregnant women was significantly higher than that of non-pregnant women (median 29.7 U/mL, range 12.2-313.2 vs. median 23.2 U/mL, range 14.6-195.1, respectively; p = 0.01). (2) Patients with preeclampsia had a significantly lower median serum concentration of sCD30 than normal pregnant women (median 24.7 U/mL, range 7.6-71.2 vs. median 29.7 U/mL, range 12.2-313.2, respectively; p < 0.05). (3) Mothers with SGA neonates had a lower median concentration of sCD30 than normal pregnant women (median 23.4 U/mL, range 7.1-105.3 vs. median 29.7 U/mL, range 12.2-313.2, respectively; p < 0.05). (4) There was no significant correlation (r = -0.059, p = 0.5) between maternal serum sCD30 concentration and gestational age (19-38 weeks) in normal pregnant women.

CONCLUSIONS

(1) Patients with preeclampsia and those who deliver an SGA neonate had a significantly lower serum concentration of sCD30 than normal pregnant women. (2) This finding is consistent with the view that preeclampsia and SGA are associated with a polarized Th1 immune response and, perhaps, a reduced Th2 response.

Pre- and post-transplant monitoring of soluble CD30 levels as predictor of acute renal allograft rejection

Identification of renal graft candidates at high risk of impending acute rejection (AR) and graft loss may be helpful for patient-tailored immunosuppressive regimens and renal graft survival. To investigate the feasibility with soluble CD30 (sCD30) as predictor of AR, sCD30 levels of 70 patients were detected on day 0 pre-transplant and day 1, 3, 5, 7, 10, 14, 21, and 30 post-transplant. AR episodes in 6 months were recorded and then patients were divided into Group AR (n=11) and Group UC (n=59). Results showed that the patients had higher pre-transplant sCD30 levels than healthy people. A significant decrease of sCD30 was observed on the first day post-transplant and continued until day 14 post-transplant. Soluble CD30 presented a stable level from day 14 to 30 post-transplant. Pre-transplant sCD30 levels of Group AR were much higher than those of Group UC (P<0.001). Patients of Group AR also had higher sCD30 levels than those of Group UC on day 1, 3, 5, 7, 10 and 14 (P<0.001). The sCD30 level presented a significantly delayed decrease in the patients of Group AR. Statistical results showed that the highest value of area under ROC curve (0.95) was obtained on day 5 post-transplant, suggesting that sCD30 levels on day 5 are of high predictive value. Therefore, sCD30 level may be a good marker of increased alloreactivity and of significant predictive value. It's necessary to monitor the variation of sCD30 in the early period post-transplant.