Background: Recent results have indicated that high prerenal and postrenal transplant soluble CD30 levels may be associated with an increased acute rejection and graft loss. The aim of this study was to evaluate the feasibility of using serum sCD30 as a marker for predicting acute graft rejection.
Materials and Methods: In this prospective study, we analyzed clinical data of 80 patients, whose pretransplant and posttransplant serum levels of sCD30 were detected by enzyme-linked immunoassay. Eight patients developed acute rejection, 7 patients showed delayed graft function, and 65 recipients experienced an uncomplicated course group. The patients were followed for 12 months, and there were no deaths.
Results: Preoperative sCD30 levels of 3 groups were 96.2 ± 32.5, 80.2 ± 28.3,
and 76.8 ± 29.8 U/mL (P = .28). After transplant, a significant decrease in the
sCD30 level was detected in 3 groups on day 14 posttransplant (P < .001), while
sCD30 levels of acute rejection group remained significantly higher than delayed
graft function and nonrejecting patients
(28.3 ± 5.2, 22.1 ± 3.2, and 19.8 ± 4.7 U/mL) (P = .02). Positive panel reactive antibody was not statistically different among groups (P = .05). Also, hemodialysis did not affect sCD30 levels (P = .05). Receiver operating characteristic curve demonstrated that the sCD30 level on day 14 posttransplant could discriminate patients who subsequently suffered acute allograft rejection (area under receiver operating characteristic curve, 0.95). According to receiver operating characteristic curve, 20 U/mL may be the optimal operational cutoff level to predict impending graft rejection (specificity 93.8%, sensitivity 83.3%).
Conclusions: Measurement of the soluble CD30 level on day 14 after transplant might offer a noninvasive means for recognizing patients at risk of acute graft rejection during the early posttransplant period.
Key words : Soluble CD30, Delayed graft function, Graft loss
Although the improved immunosuppressant protocols have reduced the rate of acute rejection, early posttransplant acute rejection is still one of the major causes of the early graft dysfunction, morbidity, mortality, and late kidney graft loss (1). All described problems may be related to a lack of immunologic tests to predict, diagnose, and reduce the risk of rejection as early as possible. In addition, it is important to consider the adverse events of immunosuppressive agents such as cancer, infection, and toxicity. So, detecting high-risk patients for rejection is an important point in organ transplant to rationally administer appropriate dosages of immunosuppressive therapy for low-risk and high-risk patients to prevent rejection (1, 2).
The early phase of diagnosis of acute allograft rejection might aid clinicians to perform required procedures to prevent undesirable posttransplant complications. However, to the best of our knowledge, acute rejection is currently confirmed by needle biopsy, which is known to be an invasive practice. Thus, we believe that the development of noninvasive diagnostic methods for evaluating graft rejection should be given high priority in the medical field. In this venue, monitoring the expression of T-cell derived CD30 has proven to be a valuable, noninvasive method for predicting renal graft rejection.
CD30 is a member of the tumor necrosis factor super family, which is abundantly expressed on T cells; and secret, T-helper, 2-type cytokines (3, 4), but in a soluble form of CD30 (sCD30), is released into circulation after activation of CD30+ T cells (5). Recent studies suggest that high prerenal and postrenal transplant, soluble CD30 levels may be associated with increased incidence of acute rejection and graft loss (6, 7). Nevertheless, other studies have reported no association between pretransplant plasma levels of sCD30 and acute rejection episodes (8). We designed this prospective study to evaluate the feasibility of using serum sCD30 level for predicting acute rejection in sera of renal allograft recipients before and after transplant.
Method and Patients
Patients and immunosuppressive protocols
Between April 2007 and June 2008, 80 patients who received kidney grafts from unrelated-living donors were included in this prospective study. Written, informed consent was obtained from each patient. The surgical methods for all recipients were similar for all patients. Briefly, an end-to-end arterial anastomosis was performed between renal transplanted artery and the internal iliac artery. The renal vein was anastomosed to external iliac vein, with an end-to-side anastomosis. The ureters were anastomosed by using the anterior Lich-Gregoir technique; and stenting was carried out in all ureters (which were removed after 2 weeks). Also, the same triple immunosuppressive protocol therapy including cyclosporine, mycophenolate mofetil, and prednisolone was administered for all recipients. Acute rejection was diagnosed by a progressive elevation of serum creatinine (> 20% of baseline serum creatinine) responding to antirejection therapy and clinical signs of rejection including fever (> 38%), decreased urine secretion, hypertension, and pain over an enlarged kidney graft that was confirmed by biopsy. Incidence of delayed graft function was defined as the need for hemodialysis during the first 7 days after transplant. The following data were recorded: donor and recipient age, recipient sex, recipient weight, warm ischemia time, panel reactive antibody (positive), history of dialysis, pretransplant, and posttransplant CD30.
Serum sCD30 assay
Blood samples were obtained on day 0 (before transplant) and on day 14 after transplant. The samples were analyzed for sCD30 by using a commercially available, enzyme-linked immunoassay kit (Bender MedSystems GmbH, Wien, Austria) in accordance with the manufacturer’s instructions. The absorbance of microwells was measured at 450 nm. The concentration of sCD30 was determined by comparing the optical density of sample wells with the optical density of wells with standard dilutions of sCD30.
Data are shown as means ± SD. Statistical analyses were performed with SPSS software for Windows (Statistical Product and Service Solutions, version 15.0, SSPS Inc, Chicago, IL, USA) was used for statistical analysis. The statistical significance of differences between means was determined by Mann-Whitney U test, and the independent and paired t test were used to compare levels at days 0 and 14. A conventional receiver operating characteristic curve was used to determine the sensitivities and specificities for sCD30 levels for patients, with and without, acute rejection. Receiver operating characteristic curve also was used to determine the sensitivities and specificities for sCD30 measurements to predict acute rejection. The area under the receiver operating characteristic curves, and the 95% confidence interval limits, were calculated using the method of Hanley and McNeil. Values were defined as significant when the values for P were defined as P < .05.
During 12-month posttransplant follow-up, the patients were divided into 3 groups according to their clinical course: 8 patients developed acute rejection, 7 patients showed delayed graft function, and 65 recipients experienced primary graft function uncomplicated course. Episodes of acute rejection were clinically diagnosed and biopsy proven in all patients. Two patients had acute rejection on the first day after transplant, and the other patients had rejection on days 15 to 19 after transplant (average in 16.8 ± 1.3 days after transplant). The demographic characteristics of patients were represented in Table 1, which shows no significant differences between groups. Preoperative sCD30 levels of 3 groups (acute rejection, delayed graft function, and uncomplicated course group) were 96.2 ± 32.5, 80.2 ± 28.3, and 76.8 ± 29.8 U/mL with no statistical difference (P = .28). However, significant decreases in sCD30 plasma level were detected between the 3 groups on 14th day after transplant. Despite a significant decrease, groups of patients with acute rejection had higher CD30 concentrations on the 14th day after the transplants, compared with delayed graft function and uncomplicated course groups (28.3 ± 5.2, 22.1 ± 3.2, and 19.8 ± 4.7 U/mL) (P = .02) (Table 2). Receiver operating characteristic curve demonstrated that the sCD30 level on the 14th day after transplant could discriminate patients who subsequently suffered acute allograft rejection (area under receiver operating characteristic curve 0.95). According to receiver operating characteristic curve, 20 U/mL might be an operational cutoff level to predict impending graft rejection (specificity 93.8%, sensitivity 83.3%). Most importantly, the decrease of sCD30 after treatment in the acute rejection group was significantly more than the other groups. Panel reactive antibody score analyses did not show significant differences between groups, and the results showed that there was no correlation between panel reactive antibody score and sCD30 levels (P = .43).
The results of this study demonstrate that a higher soluble CD30 concentration on day 14 after transplant is a good marker for predicting the acute rejection. Our findings showed that the pretransplant sCD30 levels were not associated with acute transplant episodes during the 12-month posttransplant period. Reports from the collaborative transplant study have suggested that highly soluble CD30 levels before or after renal transplant are associated with increased acute renal rejection and graft loss (6, 7). Results of our study are in agreement with reports suggesting a correlation between high posttransplant sCD30 content and acute response (8, 9). Two other studies by Sengul and associates, and Ayed and associates, also have indicated an association between posttransplant (day 15), sCD30 levels, and increased risk of early acute response (10, 11). Nevertheless, the predictive value of pretransplant sCD30 levels for acute response remain controversial. Some studies have reported that the pretransplant sCD30 level has a correlation with the posttransplant allograft loss (7, 12), but this has not been confirmed by others. The study by Slavcev and associates could not confirm that high sCD30 levels might have a predictive value for the incidence of acute response (13). The study by Weimer and associates (14) with 84 patients also did not find pretransplant sCD30 levels to have a predictive value in acute rejection. On the other hand, Altermann and associates (15) noted that during a 1-year period, sCD30 measured on 4 occasions in patients with end-stage renal disease were variable for each patient.
These results indicate that there is no absolute universal cutoff value for the pretransplant sCD30 level that can be used to predict acute response. Most of our recipients had sCD30 plasma level averaging less than 100 U/mL, which is similar to the report by Altermann and associates, who found that more than 80% of patients had a level of < 100 U/mL (15). In this study, although a significant decrease of sCD30 was detected after transplant in all patients, sCD30 concentrations in patients with acute rejection, were significantly higher than the group without acute rejection, which is in agreement with the study of Dang and associates (8), though the average sCD30 value (24.3 ± 5.2) was slightly higher in our study.
Our results demonstrate that a higher soluble CD30 concentration on day 14 after transplant is associated with acute rejection. Our plan was to determine a cutoff point for sCD30 level detect patients prone to rejection after organ transplant. Receiver operating characteristic curve demonstrated that sCD30 level on day 14 after the transplant could discriminate patients who subsequently suffer acute allograft rejection (area under receiver operating characteristic curve, 0.95). According to receiver operating characteristic curve in this study, 20 U/mL might be an operational cutoff level to predict impending graft rejection (specificity 93.8%, sensitivity 83.3%). Taken together, there are still some controversies in the role of sCD30 in organ rejection, but despite these controversies, there is clear evidence in support of a role for sCD30 in graft rejection. The important finding of our study is that sCD30 levels appear to be independent of classic immunologic risk factors such as panel reactive antibody formation, retransplant, and preoperative blood transfusions.
In this study, sCD30 levels were significantly higher in patients with acute graft rejection, and most of rejection episodes occurred more than 14 days after transplant (on the third week after transplant). Previous reports indicated an association between posttransplant (day 15) sCD30 levels and increased risk of early acute rejection (10, 11). Therefore, to confirm the feasibility of the test on the 14th day after transplant, further studies with greater samples are suggested to clarify whether the serum sCD30 level can be used as a marker of allograft rejection (which might help in developing immunosuppressant regimen protocols after renal transplant).
Measurement of soluble CD30 level on 14th day after transplant might offer a noninvasive means of recognizing patients at risk of acute graft rejection during early posttransplant period.
Volume : 7
Issue : 4
Pages : 237 - 240
1Hasheminezhad Hospital, Department of Urology, Iran University of Medical Science (IUMS), Tehran, Iran.
2Immunology Department, Faculty of Medicine, Shahid Beheshti University of Medical Science, Tehran, Iran.
3Faculty of Medicine, Tehran University of Medical Science (TUMS), Tehran, Iran. 4Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, MO.
Address reprint requests to: Mohammad Amin Abbasi, MD, Vanak Sq., Vaalinejad Ave., Tehran, Iran
Table 1. Demographic characteristics of kidney allograft recipients.
Table 2. sCD30 plasma levels (U/mL) of patients in three groups.