J. N.M. IJzermans

Ischemia times and donor serum creatinine in relation to renal graft failure

Background. The results of renal transplantation are dependent on many variables. To simplify the decision process related to a kidney offer, the authors wondered which variables had the most important influence on the graft failure risk. Methods. All transplant patients (n=1,124) between January 1981 and July 2000 were included in the analysis (2.6% had missing values). The variables included were donor and recipient age and gender, recipient original disease, race, donor origin, current smoking, cardiovascular disease, body weight, peak and current panel reactive antibody (PRA), number of preceding transplants, type and duration of renal replacement therapy, and time since failure of native kidneys. Also, human leukocyte antigen (HLA) identity or not, first and second warm and cold ischemia times, left or right kidney and fossa, donor kidney anatomy, donor serum creatinine and proteinuria, and transplantation year were included. Results. In a multivariate model, cold ischemia time and its time-dependent variable significantly influenced the graft failure risk censored for death (P <0.0001) independent of any of the other risk factors. The influence primarily affected the risk in the first week after transplantation; thereafter, it gradually disappeared during the first year after transplantation. Donor serum creatinine also significantly influenced the graft failure risk in a time-dependent manner (P <0.0001). The risk of a high donor serum creatinine is already enlarged in the immediate postoperative phase and increases thereafter; the curve is closely related to the degree of the elevation. The other variables with a significant influence on the graft failure rate were, in order of decreasing significance, recipient age, donor gender, donor age, HLA identity, transplantation year, preceding transplantations, donor origin, and peak PRA. Conclusions. Donor serum creatinine and cold ischemia time are important time-dependent variables independently influencing the risk of graft failure censored for death. The best strategy for improving the results of cadaveric transplantations is to decrease the cold ischemia time and to allocate kidneys from donors with an elevated serum creatinine to low-risk recipients.

The superior results of living-donor renal transplantation are not completely caused by selection or short cold ischemia time: a single-center, multivariate analysis.

Background. The results of living-donor (LD) renal transplantations are better than those of postmortem-donor (PMD) transplantations. To investigate whether this can be explained by a more favorable patient selection procedure in the LD population, we performed a Cox proportional hazards analysis including variables with a known influence on graft survival. Methods. All patients who underwent transplantations between January 1981 and July 2000 were included in the analysis (n=1,124, 2.6% missing values). There were 243 LD transplantations (including 30 unrelated) and 881 PMD transplantations. The other variables included were the following: donor and recipient age and gender, recipient original disease, race, current smoking habit, cardiovascular disease, body weight, peak and current panel reactive antibody, number of preceding transplants and type and duration of renal replacement therapy, and time since failure of native kidneys. In addition, the number of human leukocyte antigen identical combinations, first and second warm and cold ischemia periods, left or right kidney and fossa, donor kidney anatomy, donor serum creatinine and proteinuria, and transplantation year were included. Results. In a multivariate model, donor origin (PMD vs. LD) significantly influenced the graft failure risk censored for death independently of any of the other risk factors (P =0.0303, relative risk=1.75). There was no time interaction. When the variable cold ischemia time was excluded in the same model, the significance of the influence of donor origin on the graft failure risk increased considerably, whereas the magnitude of the influence was comparable (P =0.0004, relative risk=1.92). The influence of all other variables on the graft failure risk was unaffected when the cold ischemia period was excluded. The exclusion of none of the other variables resulted in a comparable effect. Donor origin did not influence the death risk. Conclusion. The superior results of LD versus PMD transplantations can be partly explained by the dichotomy in the cold ischemia period in these populations (selection). However, after adjustment for cold ischemia periods, the influence of donor origin still remained significant, independent of any of the variables introduced. This superiority is possibly caused by factors inherent to the transplanted organ itself, for example, the absence of brain death and cardiovascular instability of the donor before nephrectomy.

Technical considerations and pitfalls in laparoscopic live donornephrectomy

BackgroundRecent developments in laparoscopic solid organ surgery suggest a possible reduction in postoperative discomfort and disability for kidney donors. Technical aspects and the influence of surgical experience in laparoscopic donor nephrectomy were evaluated.MethodsThe clinical outcome of 57 laparoscopic donor nephrectomies (LapNx) was compared with that for a historic control group of 27 open donor nephrectomies (OpenNx).ResultsThree conversions to open nephrectomy (5.2%) were necessary. Postoperative complications were minor and comparable in both groups. Patients who under-went laparoscopic surgery demonstrated significantly less postoperative pain and a shorter hospital stay, but operative time and warm ischemia time were significantly longer. Graft survival after LapNx was 100% during a median follow-up period of 13 months. Operative time for LapNx decreased considerably with experience gained and seemed to be less for right nephrectomy. Stenotic ureter-bladder anastomoses occured after LapNx in four patients during the first half year (7.0%), but this problem seemed to be resolved after modification of the technique.ConclusionLapNx is associated with less postoperative discomfort and improved convalescence.

A Single-Lumen Central Venous Catheter for Continuous and Direct Intra-abdominal Pressure Measurement

Background:Abdominal compartment syndrome (ACS) is associated with high morbidity and mortality rates. Therefore, the need for a good diagnostic tool to predict intra-abdominal hypertension (IAH) and progression to ACS is paramount. Bladder pressure (BP) has been used for several years for intra-abdominal pressure (IAP) measurement but has the disadvantage that it is not a continuous measurement. In this study, a single-lumen central venous catheter (CVC) is placed through the abdominal wall into the abdominal cavity to continuously and directly monitor the intraabdominal pressure (CDIAP). The aim of this study was to evaluate the use of CDIAP to measure BP as a representative of the true IAP.Methods:Both BP and CDIAP were prospectively recorded on a variety of surgical patients admitted to the intensive care unit (ICU) from March 2003 up to December 2004. At the end of the surgical procedure, the CVC was placed through the abdominal wall and connected to a pressure transducer. In addition, the BP was measured through the urine drainage port after clamping the catheter and filling the bladder with 50 ml of 0.9% saline. At least three paired measurements (BP and CDIAP) were performed for at least one day on the ICU in a standardized manner at preset time intervals on each patient. The paired measurements were compared using the Bland–Altman (B–A) method. Data are presented as mean ± standard deviation.Results:Over a period of 22 months (March 2003 until December 2004), 125 paired measurements of both BP and CDIAP were recorded on 25 patients. The mean age was 72.4 ± 6.6 years. Eighteen patients underwent central vascular surgery, and seven patients with peritonitis received laparotomy. The mean CDIAP was 11.4 ± 4.8 (range 2–30) mmHg, and the BP was 12.9 ± 5.3 (range 3–37) mmHg. The mean difference between CDIAP and BP was 1.6 ± 2.7 mmHg. There was an acceptable level of agreement (intraclass correlation 0.82) between IAP measured by BP and IAP measured via CDIAP.Conclusion:Continuous direct intra-abdominal pressure measurement proved that the BP measurement approach of Kron is representative of the IAP. CDIAP measurement is accurate and makes it easier for the nursing staff to be informed of the IAP.

Rabbit Antithymocyte Globulin Impairs the Capacity for Homeostatic Proliferation of T Cells in Kidney Transplant Patients: 1113

Introduction: Short term rabbit antithymocyte globulin (rATG) induction therapy leads to long-lasting depletion of T cells. Numbers of T cells return to baseline levels approximately one year after kidney transplantation. The biological mechanism of this phenomenon is not elucidated yet. Here we studied the hypothesis that it could be explained by an effect on the homeostatic proliferation of T cells. Material and methods: The phenotype and homeostatic proliferation capacity of T cells from renal transplant recipients (n=14) treated with rATG induction therapy (3x2mg/kg/day) in combination with tacrolimus, mycophenolate mofetil (MMF) and steroids were investigated in the first year after transplantation by whole blood phospho-specific flow cytometry. Patients (n=23) treated with the non-depleting basiliximab induction therapy (day 0; 4; 20 mg) served as a control group. Results: After a significant decrease in the absolute number of both CD4 and CD8 T cells one week after rATG therapy (p< 0.0001), T cells begin to repopulate. However, while CD8 T cells reach baseline levels approximately 3 months after induction therapy, CD4 T cells do not reach 40% of their baseline levels 12 months after transplantation. Functional analysis of the repopulated CD4 and CD8 T cells revealed an impaired Interleukin 7 (IL-7) induced Signal Transducer and Activator of Transcription 5 (STAT5) phosphorylation capacity of repopulated T cells. CD4 memory T cells, including central memory (CD45RO+CCR7+) and effector memory (CD45RO+CCR7-) subpopulations, showed a decrease in the proportion of IL-7 induced phosphorylation of STAT5 (p< 0.04 vs pre-transplantation). After rATG induction therapy, also in the CD8 memory T cells an impaired IL-7 induced STAT5 phosphorylation capacity was found that even decreases further during follow-up the first year after transplantation (p< 0.022 vs pre-transplantation). This decreased STAT5 phosphorylation capacity included the central memory, effector memory and EMRA (CD45RO-CCR7-) subpopulations. CD4 and CD8 T cells of basiliximab treated patients did not show impaired IL-7 induced STAT5 phosphorylation responses. Conclusion: CD4 and CD8 T cells showed a long-lasting impaired IL-7 induced phosphorylation capacity of STAT5 after rATG induction therapy which can explain the absence of full immune reconstitution approximately one year after rATG induction therapy. 1566

Rabbit Antithymocyte Globulin Induction Therapy Induces Expansion of HeliosnegFoxp3pos Regulatory T Cells in Kidney Transplant Patients: 1923

Introduction: Peripheral blood of rabbit antithymocyte globulin (rATG) treated kidney transplant patients show overrepresentation of newly formed regulatory T cells (Tregs) with unknown origin. To investigate whether these Tregs originate from the thymus or are induced in the periphery we studied the molecular markers for proliferation (Ki67) and thymopoiesis (CD31) in combination with Helios to discriminate between natural occurring Tregs and Tregs induced in the periphery. Materials and methods: Flow cytometric analyses were performed on peripheral blood mononuclear cells of adult patients, treated with either rATG (3 x 2mg/kg/day, n=14) or with the non-depleting anti-CD25 antibody Basiliximab (day 0, 4; 20 mg, n=23) induction therapy in combination with Tacrolimus, MMF and steroids to analyse the expression of Ki67, CD31, and Helios in Treg (CD4+CD25+CD127-FoxP3+). Results: In the presence of decreased percentages of naïve CD4+CD25CD127+ T cells, the percentages of Tregs and of activated CD4+ T cells increased in rATG treated kidney transplant patients in the first 6 months after transplantation (p<0.02 and p<0.003). This phenomenon was not observed in the Basiliximab treated group. The increase in the proportion of Tregs in the rATG group was the result of homeostatic proliferation and not of thymopoiesis. At one month after rATG therapy the percentage of homeostatic proliferating, Ki67+ regulatory T cells was significantly higher in rATG treated patients (p=0.0009), while the percentage of CD31+Ki67regulatory T cells, produced by the thymus, was comparable between groups. Proliferating Ki67+ Tregs were predominantly of the memory, CD45RO+, phenotype. To define the origin of the newly formed Treg, Helios expression was analyzed and showed to be significantly lower in the rATG treatment group compared to Basiliximab treated patients (mean 61.7%, range 21.6% 83.7% and mean 82.8%, range 75.5% 89.7% respectively, p=0.01). The Heliosneg FoxP3pos Tregs were most prominent in the Ki67+, CD45RO+ Treg subset (p=0.03, rATG vs Basiliximab). Conclusion: These data show that after rATG induction therapy the immune reconstitution in which Tregs are overrepresented, result from homeostatic proliferation of natural, but especially of periphery derived induced Tregs. 1994

Donor-Derived Tubular Epithelial Cells Induce Class I Restricted Alloreactivity in Kidney Transplant Recipients: 1488

Introduction: Although it is known from in vitro studies that human renal tubular epithelial cells (TEC) have stimulatory capacities their effect on alloreactivity in organ transplant patients is unknown. In the present study, the immunostimulatory effect of donor TEC on recipient anti-donor T-cell reactivity was examined by analysing the function and characteristics T cell subsets before and after clinical kidney transplantation. Material and methods: Recipient T-cell reactivity against donor TECs was investigated in pre-transplant and post-transplant co-culture system and transwell experiments of 6 living-kidney donor-recipient pairs. For TEC/PBMC co-culture, recipient PBMCs vs donor TEC (allogeneic coculture) and donor PBMCs vs donor TEC (autologous co-culture) were used. By flow cytometry the proliferative response of CD3, CD4, CD8 naïve (CD45ROCCR7+), effector memory (CD45RO+CCR7+), central memory (CD45RO+CCR7-) and effector memory RA (EMRA, CD45ROCCR7-) was measured. Results: After stimulation by TEC a allogeneic response was measured in the CD8+ T-cell subset, but was not found in CD4+ T-cells. No autologous induced CD8+ T-cell proliferation was found. The proliferative response in the pre-transplantation co-culture was 5.7% ± 1.2 and in the post-transplantation co-culture a response of 6.6% ± 3.1 was found. In addition, transwell experiments revealed that the TEC induced CD8+ T-cell proliferation was cell-cell contact dependent. Co-cultured CD8+ T-cells also expressed the activation marker CD69. Additionally, the vast majority of the CD8+ responding T-cells where of the memory phenotype; effector memory T cells (47%), EMRA (25%) and of central memory T cells (13%). No proliferation of the naïve CD8+ T-cell was found. Conclusion: Donor-derived TECs induce a class I restricted effector memory T-cell response in kidney transplant recipients. 1553