Evaluation of immune regulation in transplant patients using the trans vivo delayed type hypersensitivity assay

Allograft recipient IL-10 and/or transforming growth factor-beta (TGF-beta) dependent anti-inflammatory T-cell delayed type hypersensitivity (DTH) responses to donor derived antigens, or regulatory T-cell responses, have been demonstrated in rodents and transplant patients using a previously described trans vivo DTH assay. We used this assay to determine the incidence of recipient anti-inflammatory T-cell responses to donor antigens in a large cohort (n = 420) of primary kidney and simultaneous kidney-pancreas transplant patients tested a mean of 4.8 years after transplantation. The results were compared with clinical outcomes and the presence of detectable circulating alloantibodies. We found an unexpectedly high incidence (21.9%) of this anti-inflammatory T-cell response to donor antigens in these recipients. There was a significant correlation between this T-cell phenotype and the presence of detectable circulating alloantibodies (p = 0.03). There was no correlation between this T-cell phenotype and the degree of HLA mismatch. In addition, the presence of an anti-inflammatory DTH response to donor antigens did not correlate with an improved clinical outcome at a median of nearly 5 years after transplantation. These findings suggest that detection of an anti-inflammatory T-cell response to donor antigens does not identify patients that have developed graft protective, regulatory T-cell responses.

Prospective, randomized trial of steroid withdrawal in kidney recipients treated with mycophenolate mofetil and cyclosporine

Our transplant centre began a prospective, randomized trial of steroid withdrawal in low risk renal transplant recipients on triple immunosuppression consisting of mycophenolate mofetil (MMF), microemulsion cyclosporine (CSA), and prednisone. One hundred and twenty patients were randomized either to discontinue or remain on steroids (60 patients per group). Study design consisted of analyses of 1-yr outcomes after study entry. This report includes the 1-yr results plus results at last follow-up (mean follow-up 3.7 yr). There were no significant differences in rates of patient and graft survival at 1 yr or at last follow-up. Additionally, the incidences of acute and chronic rejection as well as graft function were the same at 1 yr and at last follow-up. Significant improvement was noted in total serum cholesterol and bone density at 1 yr and last follow-up. Initial improvement in patient weight at 1 yr was not sustained at last follow-up. No significant impact of steroid withdrawal on serum triglycerides, blood pressure, or post-transplant diabetes mellitus was observed. To date, we have observed no immunologic risk, and some significant benefit in regards to side effects, of steroid withdrawal between 6 and 36 months after transplantation in low risk renal transplant recipients maintained on prednisone, MMF, and microemulsion CSA.

CONCLUSION

Steroid withdrawal in low risk kidney transplant recipients is safe and ameliorates many of the unwanted sides effects of steroid use.

Excellent clinical outcomes in primary kidney transplant recipients treated with steroid-free maintenance immunosuppression

Steroid-free maintenance immunosuppression is desirable to eliminate the side effects of chronic corticosteroid use. Complete steroid avoidance or rapid post-transplant steroid withdrawal has recently been used in renal transplant recipients with encouraging results. The present study evaluated the outcome of a steroid-free maintenance immunosuppressive protocol in kidney transplant recipients with at least one-yr follow up. Between April 2002 and October 2004, a total of 301 primary kidney transplant recipients received steroid-free maintenance immunosuppression. The regimen consisted of induction with thymogobulin and prednisone for the first five d. Patients were maintained on Sirolimus and Neoral. Neoral dose was adjusted to target C2 levels and the Sirolimus dose was adjusted to a target rapamycin trough level. All primary kidney transplants (n = 502) performed in the two yr (starting January 2000) prior to institution of the steroid-free regimen and thus maintained on a steroid-based immunosuppressive protocol were used for comparison. One-year patient and death censored graft survival were 93.1% and 98.1% for the steroid-free group vs. 95.2% and 95.2% for the comparator groups (p = ns). The incidence of biopsy-proven acute rejection was 4.9% in the steroid-free group vs. 9.4% in the comparator group (p < 0.01). Two (0.7%) of 301 patients in the steroid-free group lost their grafts because of acute rejection compared with nine (1.8%) patients in the comparator group (p < 0.05). At one-yr post-transplant the mean serum creatinine level was not different between the two groups. There were no significant differences in mean serum cholesterol and triglycerides levels as well as the percentage of patients on lipid lowering agents between the groups. White blood cell counts, daily doses of Neoral and weight gain were significantly lower in the steroid-free group vs. the comparator group. However, more patients in the steroid-free group required erythropoietin and iron therapy for anemia (p < 0.001). We conclude that excellent graft survival with a significantly lower incidence of acute rejection can be achieved using a steroid-free maintenance immunosuppressive protocol consisting of Neoral and Sirolimus.

Hand-assisted laparoscopic versus open nephrectomies in living donors

Shortages of cadaveric kidneys for transplant into rising numbers of patients with end-stage renal failure have increased the demand for kidneys from live donors. The morbidity associated with traditional open donor nephrectomies (ODN) may discourage many candidates. The newer laparoscopic technique has been promoted as having less morbidity.

OBJECTIVES

To evaluate outcomes of hand-assisted laparoscopic nephrectomies (HALN) and prospectively compare HALN and ODN.

METHODS

After retrospectively reviewing donor and recipient outcomes in 33 HALN (December through August, 2000), we prospectively compared another 47 with 30 ODN performed from September 2000 through April 2001.

RESULTS

All 80 HALN were successful, with no requirement to convert to an open procedure. Four donors experienced surgery-related complications: wound infection, retroperitoneal hematoma, prolonged ileus and early small-bowel obstruction, respectively. Two recipients had ureteral complications (1 stricture, 1 leak); 5 experienced delayed graft function, 2 requiring dialysis; and 2 kidneys were lost from infarction. The prospective comparison showed the operative time for HALN (mean 184 min, standard deviation [SD] 39 min) was significantly longer (143 [SD 27] min, p < 0.01), but resulted in less blood loss (p < 0.05). Lengths of time to warm ischemia/early graft function, resumption of oral intake/first bowel movement, and hospital discharge were similar. The abdominal-wall laxity and loss of cutaneous sensation from the flank incision experienced by many ODN patients after was uncommon in the HALN group. Three months after nephrectomy, donor complaints of incisional pain were less common after HALN (p < 0.01).

CONCLUSIONS

HALN had good outcomes for donors and recipients, with quicker, more complete recoveries 3 months afterward.

Evolution of immunosuppression in kidney transplantation: the Ohio State University experience

The goals and outcomes of immunosuppression in renal transplantation have changed significantly over the last 30 years. When graft survival rates were relatively low and acute rejection was a frequent occurrence in the early era of transplantation, the goal of immunosuppression was to improve survival and reduce the rate of acute rejection. Today, with excellent graft survival rates and a low incidence of acute rejection, the goal of immunosuppression has shifted toward not only eliminating acute rejection, but also toward reducing the side effects of medications, and maintaining long-term graft function by decreasing chronic nephropathy. Between September 1982-December 2004, 3,211 primary kidney transplant procedures were performed at The Ohio State University. We excluded from analysis all combined transplants as well as patients who were involved in clinical research protocols. Our immunosuppressive protocol changed substantially over this 24-year period, which can be divided into 5 eras in time. Each era is defined by a distinct immunosuppressive protocol that resulted in an incremental improvement in outcomes of patient and graft survival rates. In the present study, the outcomes of each era in patients with previous kidney transplant only are compared and future directions are discussed. The incidence of acute rejection episodes and graft survival from each era are compared and demonstrate the substantial improvement in results that have been achieved over the past 24 years.

IFN-gamma gene polymorphisms associate with development of EBV+ lymphoproliferative disease in hu PBL-SCID mice

Posttransplantation lymphoproliferative disorder (PTLD) is a devastating post-transplantation complication often associated with Epstein-Barr virus (EBV). Although the type and length of immunosuppression are risk factors, a patient's inherent immune capacity also likely contributes to this disorder. This report uses severe-combined immunodeficient mice given injections of human peripheral blood leukocytes (hu PBL-SCID [Severe Combined Immunodeficient] mice) to test the hypothesis that cytokine genotype associates with the development of EBV-associated lymphoproliferative disease (LPD). We observed that the A/A (adenosine/adenosine) genotype for base + 874 of the interferon gamma (IFN-gamma) gene was significantly more prevalent in PBLs producing rapid, high-penetrance LPD in hu PBL-SCID mice, compared to PBLs producing late, low-penetrance LPD or no LPD. In examining the relationship between genotype and cytolytic T-lymphocyte (CTL) function, transforming growth factor beta (TGF-beta) inhibited restimulation of CTLs in PBLs with adenosine at IFNG base + 874, but not in PBLs homozygous for thymidine. Importantly, neutralization of TGF-beta in hu PBL-SCID mice injected with A/A genotype PBLs resulted in reduced LPD development and expanded human CD8(+) cells. Thus, our data show that TGF-beta may promote tumor development by inhibiting CTL restimulation and expansion. Further, our data indicate that IFNG genotype may provide valuable information for both identifying transplant recipients at greater risk for PTLD and developing preventive and curative strategies.

Magnetic Resonance Cholangiography With Mangafodipir Trisodium (Teslascan) to Evaluate Bile Duct Leaks After T-Tube Removal in Liver Transplantation

Liver transplant patients who present with abdominal pain after removal of the T-tube can be initially evaluated by contrast-enhanced magnetic resonance cholangiography (CEMRC) instead of abdominal computed tomography and hepatobiliary scintigraphy. In this article, 3 liver transplant patients who were evaluated by CEMRC after removal of the T-tube. CEMRC successfully identified the presence, location and extent of bile duct leaks, and can be performed as a diagnostic study in patients with suspected bile duct leaks.

Magnetic resonance angiography for preoperative evaluation of potential kidney donors1

BACKGROUND

Careful evaluation of the renovascular anatomy for living kidney donors is essential to optimize donor and recipient outcomes. Arteriography has been the standard for delineating the renovascular anatomy. However, this procedure is invasive. Magnetic resonance angiography (MRA) is an attractive, noninvasive alternative. The aim of this study was to evaluate the accuracy of MRA in potential living kidney donors.

METHODS

A retrospective comparison of the preoperative MRA results with the intraoperative anatomy was performed in 189 living kidney donors.

RESULTS

MRA interpretations correctly identified the vascular anatomy of the donor kidneys in 173 donors (91.5%). In the remaining 16 patients (8.5%), the MRA interpretation was inaccurate. In 10 patients, the MRA reported fewer arteries than the number encountered during the donor operation, whereas in six patients MRA reported more arteries than what found during operation. In seven patients, MRA supplied additional important anatomical information, including kidney size disparity, the presence of nephrolithiasis, the presence of a renal cyst, and renal artery stenosis. All kidneys were successfully transplanted. The misinterpretation of the MRA did not adversely affect the recipient outcome.

CONCLUSION

The noninvasive MRA evaluation of donor renovascular anatomy is an acceptable substitute for traditional angiography.

EBV kidney allograft infection: possible relationship with a peri-graft localization of PTLD

Post-transplant lymphoproliferative disorder (PTLD) is a grave complication of transplantation and the result of uncontrolled proliferation of B lymphocytes infected with Epstein-Barr virus (EBV). Herein we assess whether EBV infects renal grafts and whether there is a relationship between EBV kidney infection and PTLD. Allograft biopsies from 23 patients with PTLD were studied for the presence of EBV DNA and RNA (EBER-1, -2) by in situ hybridization and for CD21 by immunohistochemistry. Results were compared to 43 transplants from people without PTLD. EBV DNA and RNA were detected in 11/43 patients without PTLD (26%), and in 15/23 (65%) patients with PTLD (p = 0.004). EBV DNA and RNA localized to proximal tubular cells and these cells showed up-regulation of the EBV receptor CD21. EBV-infected allografts were noted in 12/12 patients with PTLD located near the allograft and in 3/11 (27%) of patients with PTLD distant from the graft. Multiple biopsies in eight patients showed that graft EBV infection can precede the diagnosis of PTLD by as long as 42 months. It is concluded that EBV can infect kidney allografts, and there appears to be a relationship between this infection and the presence of PTLD near the graft.

Twenty years of renal transplantation at Ohio State University: the results of five eras of immunosuppression

Over the past 20 years, more than 4,000 patients have undergone an abdominal solid organ transplant at Ohio State University. The 20-year period can be divided into five eras, each defined by an immunosuppressive protocol used during that period. With each successful era came a new immunosuppressive protocol that produced an incremental improvement in outcomes of patients and graft survival resulting from the application of the newest and most sophisticated combination of immunosuppressive drugs. The incidence of acute rejection episodes and graft survival from each era are compared and demonstrate the substantial improvement in results that has been achieved over the past 20 years.

The impact of mycophenolate mofetil dosing patterns on clinical outcome after renal transplantation

BACKGROUND

Mycophenolate mofetil (MMF) has proven to be a very effective drug for the prevention of acute rejection following renal transplantation when dosed as prescribed at 2 or 3 g/d. However, circumstances arise in clinical transplantation where the dose must be lowered, either to avoid drug toxicity or because of concurrent infection. The impact on the incidence of acute rejection and graft survival when the MMF dose must be lowered has not previously been investigated.

METHODS

In this study, a cohort of 721 kidney transplant recipients who received immunosuppression using MMF in conjunction with cyclosporine and prednisone and OKT3 (n = 425) or Simulect (n = 296) induction were evaluated. Clinical outcomes were compared and contrasted between patients with and without MMF dose changes within the first year post-transplantation.

RESULTS

The majority of patients (70.3%, n = 507) had at least one dose change within the first post-transplant year. Compared with the 214 patients who did not have a dose change, these patients had a much higher incidence of acute rejection within the first post-transplant year (23.3% vs. 3.7%, p < 0.001). This resulted in a significantly decreased 3-yr death-censored graft survival (76.3% vs. 88.3%, p = 0.003). The incidence of acute rejection for patients who had a dose change was highest if the dose change occurred within the first post-transplant month (34.4%). The incidence of acute rejection for the dose change patients was influenced by recipient ethnicity (African-American vs. Caucasian) and the type of induction agent used (OKT3 vs. Simulect).

CONCLUSION

Altering the dose of MMF within the first post-transplant year correlated with a significantly worse clinical outcome in this cohort of renal transplant recipients. These data suggest that avoidance of MMF dose changes within the first year after renal transplantation would result in improved graft survival.

Simultaneous pancreas-kidney transplantation at a single center

Simultaneous pancreas-kidney transplantation (SPKT) is the procedure of choice in our program to treat type I diabetic patients with end-stage renal disease. Its value in type II diabetic patients remains to be carefully evaluated. With the improvements in the technical results and immunosuppression medications, the procedures have become safer than those performed in the previous decade. However, the diabetic host is a high-risk individual. Careful evaluation and selection is prudent to maintain excellent results with this scarce organ. As we have seen in this series, death is the number one cause of graft loss and improved pre-operative evaluation will continue to be of significant value to lower the mortality rate of SPKT. The success of SPKT has led to wider application of this procedure to less than ideal recipients. Due to the shortage of organs, there is a trend to use more marginal donors. The use of marginal donors and marginal recipients requires careful evaluation to maintain safety and cost effectiveness. At our center, long-term patient and graft survival rates have been acceptable. We will continue to use SPKT as the procedure of choice for acceptable candidates. There has been a trend to change our philosophy to use living donors for the kidney transplant followed by a sequential pancreas transplant in order to overcome the shortage of organs. The issue of primary enteric drainage has not been addressed in this report due to our success with bladder drainage, as we feel that it is a safer procedure and are comfortable that patient education and outpatient therapy has minimized the problems with its use. Despite the lower threshold for enteric conversion, fewer than 10% of our patients undergo conversion when they are at low risk for complications.

High incidence of donor-reactive delayed-type hypersensitivity reactivity in transplant patients

Evidence of transplant recipient cellular sensitization towards donor antigens has rarely been directly measured. Rather, sensitization has been generally inferred by the presence of detectable allo-reactive or donor-reactive antibodies. In this study a newly developed delayed-type hypersensitivity assay was used to directly determine the incidence of post-transplant donor-reactive T-cell sensitization in a large cohort of kidney and simultaneous kidney-pancreas recipients. These results were compared with the presence of detectable circulating alloantibodies and with patient clinical outcome. We found an unexpectedly high incidence (52%) of donor-reactive delayed-type hypersensitivity reactivity in our study patients. Donor-reactive delayed-type hypersensitivity reactivity occurred at a much higher frequency than detectable alloantibodies (20%). Further, we found no correlation between the presence of alloantibodies and donor-reactive delayed-type hypersensitivity reactivity. We also found no correlation between the development of donor-reactive delayed-type hypersensitivity reactivity and the degree of donor and recipient HLA matching. Finally, the presence of detectable donor-reactive delayed-type hypersensitivity reactivity did not correlate with a worse clinical outcome at the time of these analyses. We conclude that in transplant recipients, the presence of circulating alloantibodies is a poor indicator of previous T-cell sensitization to donor antigens. We also conclude that our current immunosuppression strategies are relatively ineffective at blocking T-cell allosensitization, but are very effective at blocking the biological consequences of that allosensitization.

Successful treatment of posttransplantation lymphoproliferative disorder (PTLD) following renal allografting is associated with sustained CD8(+) T-cell restoration

Posttransplantation lymphoproliferative disorder (PTLD) is a life-threatening Epstein-Barr virus (EBV)-associated B-cell malignancy occurring in 1% to 2% of renal transplantation patients. Host- and PTLD-related factors determining the likelihood of tumor response following reduction of immune suppression (IS) and antiviral therapy remain largely unknown. Standard therapy for PTLD is not well established. Eleven consecutive renal transplantation patients who developed EBV-positive PTLD 8 to 94 months after allografting were uniformly treated with acyclovir and IS reduction. All PTLDs were EBV-positive diffuse large B-cell lymphomas. Ten patients (91%) obtained a durable complete response (CR), and 9 (82%) have remained in continuous CR with a median follow-up of 29 months. Five patients (45%) lost their allograft. Of these, 4 patients had PTLD affecting the transplanted kidney. Peripheral blood CD8(+) T cells increased significantly (P =.0078) from baseline in 8 responders available for analysis. One of 2 patients whose absolute CD8(+) T-cell count subsequently dropped to baseline after IS reduction relapsed. The expanded CD8(+) T cells from 2 responders specifically recognized an immunodominant peptide from the EBV lytic gene BZLF-1. Another lytic EBV gene, thymidine kinase, was expressed in all 8 PTLDs tested. IS reduction and antiviral therapy for PTLD after renal transplantation is a highly successful therapeutic combination, but the risk of graft rejection is significant, particularly in patients with PTLD involving the renal allograft. A sustained expansion of CD8(+) T cells and a cellular immune response to EBV lytic antigens may be important for PTLD clearance in renal transplantation patients.

Patient survival after renal transplantation III: the effects of statins

BACKGROUND

Kidney transplant recipients have high cardiovascular risk and an unfavorable cardiovascular risk profile, which frequently includes hyperlipidemia. Although the use of HMG-CoA reductase inhibitors (statins) is associated with improved survival in the general population, the effects of these drugs on the survival of kidney transplant recipients have not been established.

METHODS

In this study, we determined which factors were associated with the use of statins in a population of 1,574 adult, kidney allograft recipients, transplanted in one institution. A risk factor analysis of patient survival was done with a primary focus on the possible relationship between statin use and survival.

RESULTS

The percent of patients treated with statins increased progressively from 1982 to 1996. Statins were used significantly more often in whites (30%) than in blacks (20%, P = 0.001) and in older individuals. These differences in statin use were not due to differences in lipid levels among the patient groups. As expected, the group of patients treated with statins had significantly higher serum lipid levels than untreated patients. Patient survival was significantly better in patients treated with statins than in untreated patients. That relationship became apparent, however, only after controlling for three additional factors: recipient age, transplant year, and serum cholesterol levels. In a multivariable Cox survival model, patient survival was associated significantly with statin use (hazard ratio [HR] = 0.76; confidence interval [CI], 0.6 to 0.96; P = 0.02), recipient age (HR = 1.05; CI, 1.04 to 1.06; P < 0.0001), and transplant year (HR = 1.05; CI, 1.01 to 1.08; P = 0.001). The serum cholesterol level was not associated significantly with patient survival in this model, but cholesterol significantly modified the relationship between statin use and patient survival.

CONCLUSIONS

Renal transplant recipients treated with statins have a 24% better survival than patients who do not receive these drugs.

Evidence that a similar range of alloimmune responses can develop in murine and human allograft recipients

Based on discrepancies between various laboratory and clinical observations, skepticism has developed regarding the pre-clinical value of rodent immunologic studies. In this article, we review the progression of our murine and human studies over the last several years, which have demonstrated that humans and mice can make very similar types of immune responses in vivo to allografts. Early studies by ourselves and others, demonstrated that mice can make either pro-inflammatory (rejection) or anti-inflammatory (acceptance) immune responses to graft alloantigens. We demonstrated that donor-reactive DTH assays could be used to monitor which type of alloimmune response had been selected by the allograft recipient. To help determine if similar immune response options are available to humans and detectable by DTH assays, we first developed the transvivo DTH assay. In this system, mice are used as a receptacle in which DTH responses made by human PBMC can be induced and measured. These transvivo DTH studies revealed that human allograft recipients, like mice, commonly make either pro-inflammatory or anti-inflammatory immune responses to graft alloantigens. In transplant patients, this rarely correlates with the development of donor-reactive alloantibodies during the post-transplant period.

The graft helps to define the character of the alloimmune response

INTRODUCTION

In mice, kidney and liver allografts may be spontaneously accepted, whereas cardiac and skin allografts in the same strain combinations are rapidly rejected. The reasons for this dichotomy in murine response outcomes remains to be determined.

METHODS AND RESULTS

When DBA/2 (H-2d) cardiac allografts were placed in C57BL/6 (H-2b) recipients, they were rejected within 10 days, unless the allograft recipients were transiently treated with gallium nitrate (GN), at which time the allografts were accepted for > 150 days. The cardiac allograft rejector mice displayed DBA/2-reactive DTH responses, whereas the cardiac allograft acceptor mice displayed both TGFbeta- and IL10-mediated inhibition of DTH responses. In contrast, DBA/2 kidney allografts placed at the same location in C57BL/6 mice were spontaneously accepted without immunosuppression. These kidney allograft acceptor mice displayed TGFbeta-mediated, but not IL10-mediated inhibition of donor-reactive DTH responses.

CONCLUSIONS

In the DBA/2-> C57B1/6 strain combination, cardiac allografts induce pro-inflammatory immunity and allograft rejection, while kidney allografts induce anti-inflammatory immunity and allograft acceptance despite the fact that both organs display the same strong MHC disparities and are implanted at the same location. Anti-inflammatory immunity and allograft acceptance are displayed by cardiac allograft recipients when they are transiently treated with select immunosuppressants. Thus, multiple immune response options are available to the organ allograft recipient, and the choice is determined, to some degree, by the allograft, itself.

Clinical significance of MHC-reactive alloantibodies that develop after kidney or kidney-pancreas transplantation

The purpose of this study was to determine the relationships between acute rejection, anti-major histocompatibility complex (MHC) class I and/or class II-reactive alloantibody production, and chronic rejection of renal allografts following kidney or simultaneous kidney-pancreas transplantation. Sera from 277 recipients were obtained pretransplant and between 1 month and 9.5 years post-transplant (mean 2.6years). The presence of anti-MHC class I and class II alloantibodies was determined by flow cytometry using beads coated with purified MHC molecules. Eighteen percent of recipients had MHC-reactive alloantibodies detected only after transplantation by this method. The majority of these patients produced alloantibodies directed at MHC class II only (68%). The incidence of anti-MHC class II, but not anti-MHC class I, alloantibodies detected post-transplant increased as the number of previous acute rejection episodes increased (p = 0.03). Multivariate analysis demonstrated that detection of MHC class II-reactive, but not MHC class I-reactive, alloantibodies post-transplant was a significant risk factor for chronic allograft rejection, independent of acute allograft rejection. We conclude that post-transplant detectable MHC class II-reactive alloantibodies and previous acute rejection episodes are independent risk factors for chronic allograft rejection. Implementing new therapeutic strategies to curtail post-transplant alloantibody production, and avoidance of acute rejection episodes, may improve long-term graft survival by reducing the incidence of chronic allograft rejection.

A randomized prospective trial of OKT3 induction in the current immunosuppression era

Recent improvements in immunosuppression and subsequent decreases in the incidence of acute rejection have brought into question the benefit of the use peri-transplant antibody therapy (i.e. induction therapy). In the current era of immunosuppression that includes mycophenolate mofetil (MMF) and cyclosporine emulsion (Neoral, Novartis, Basle, Switzerland), we designed and have completed a prospective, randomized trial to address this question. Cadaveric and living donor renal allograft recipients were randomized to receive either OKT3/MMF/delayed Neoral/prednisone or MMF/immediate Neoral/prednisone without OKT3. The incidence of rejection episodes was the primary end point. Patients with delayed graft function were excluded. All rejection episodes were biopsy proven and all patients have been followed for a minimum of 2 yr. Fifty-four patients received OKT3 induction, of which 6 patients suffered a rejection episode (11%), while 13 patients (27%) not receiving OKT3 (p=0.04) had a rejection episode. Four patients in the no OKT3 group suffered multiple rejections, while there were only 2 with more than one episode in the OKT3 group. There was no increased incidence of infectious complications in the group receiving OKT3. Hospital costs tended to be higher in the OKT3-treated group, but were not significantly different. The low incidence of rejection in the OKT3-treated group was intriguing and validates the use of antibody therapy in the early post-operative periods even in the era of improved baseline immunosuppression.