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Solid organ transplant recipients (SOTRs) are less likely to mount an antibody response to SARS-CoV-2 mRNA vaccines. Understanding risk factors for impaired vaccine response can guide strategies for antibody testing and additional vaccine dose recommendations.Using a nationwide observational cohort of 1031 SOTRs, we created a machine learning model to explore, identify, rank, and quantify the association of 19 clinical factors with antibody responses to 2 doses of SARS-CoV-2 mRNA vaccines. External validation of the model was performed using a cohort of 512 SOTRs at Houston Methodist Hospital.Mycophenolate mofetil use, a shorter time since transplant, and older age were the strongest predictors of a negative antibody response, collectively contributing to 76% of the model's prediction performance. Other clinical factors, including transplanted organ, vaccine type (mRNA-1273 versus BNT162b2), sex, race, and other immunosuppressants, showed comparatively weaker associations with an antibody response. This model showed moderate prediction performance, with an area under the receiver operating characteristic curve of 0.79 in our cohort and 0.67 in the external validation cohort. An online calculator based on our prediction model is available at http://transplantmodels.com/covidvaccine/ .Our machine learning model helps understand which transplant patients need closer follow-up and additional doses of vaccine to achieve protective immunity. The online calculator based on this model can be incorporated into transplant providers' practice to facilitate patient-centric, precision risk stratification and inform vaccination strategies among SOTRs.

Background Combined liver-kidney transplantation (CLKT) improves survival for liver transplant recipients with renal dysfunction; however, the tenuous perioperative hemodynamic and metabolic milieu in high-acuity CLKT recipients increases delayed graft function and kidney allograft failure. We sought to analyze whether delayed KT through pumping would improve kidney outcomes following CLKT. Methods A retrospective analysis (University of California Los Angeles [n = 145], Houston Methodist Hospital [n = 79]) was performed in all adults receiving CLKT at 2 high-volume transplant centers from February 2004 to January 2017, and recipients were analyzed for patient and allograft survival as well as renal outcomes following CLKT. Results A total of 63 patients (28.1%) underwent delayed implantation of pumped kidneys during CLKT (dCLKT) and 161 patients (71.9%) received early implantation of nonpumped kidneys during CLKT (eCLKT). Most recipients were high-acuity with median biologic model of end-stage liver disease (MELD) score of, 35 for dCLKT and 34 for eCLKT (P = ns). Pretransplant, dCLKT had longer intensive care unit stay, were more often intubated, and had greater vasopressor use. Despite this, dCLKT exhibited improved 1-, 3-, and 5-year patient and kidney survival (P = 0.02) and decreased length of stay (P = 0.001), kidney allograft failure (P = 0.012), and dialysis duration (P = 0.031). This reduced kidney allograft futility (death or continued need for hemodialysis within 3 mo posttransplant) for dCLKT (6.3%) compared with eCLKT (19.9%) (P = 0.013). Conclusions Delayed implantation of pumped kidneys is associated with improved patient and renal allograft survival and decreased hospital length of stay despite longer kidney cold ischemia. These data should inform the ethical debate as to the futility of performing CLKT in high-acuity recipients.

The novel coronavirus SARS-CoV-2 [coronavirus disease 2019 (COVID-19)] is a highly contagious and devastating virus that has currently infected over 2.5 million people worldwide and resulted in 177 641 deaths as of April 2020.1 Although most people diagnosed with COVID-19 exhibit mild-to-moderate symptoms, early reports from China described vulnerable patient populations, such as the elderly and those with chronic underlying medical conditions including the immunosuppressed, having more severe COVID-19-related illness compared to the general population.2,3 Solid organ transplant (SOT) recipients are one of the largest cohorts of immunosuppressed patients, yet little is known about their risk of contracting the virus, postinfection outcomes, and effect of immunosuppression on the clinical course of the disease. Unique challenges, such as immunosuppression management and interpretation of laboratory data, also exist. Current treatment strategies borrow upon prior experience from other pandemics, such as severe acute respiratory syndrome (SARS) and influenza A virus subtype.4 SARS-CoV-2 primarily affects the respiratory tract, progressing from pneumonia to acute respiratory distress syndrome in severe cases.5 In these cases, there is a recognized cytokine release syndrome (CRS) that when occurs results in multiorgan dysfunction and failure.6 The role of immunosuppression in mounting such inflammatory response is unclear. Inflammatory markers, such as C-reactive protein (CRP), lactate dehydrogenase (LDH), and D-dimer, may reflect disease progression and/or severity.7 Lymphopenia is reported as a common presentation among COVID-19 positive patients.8,9 Treatment options are limited. Antivirals such as hydroxychloroquine (HCQ) with or without azithromycin are widely used empiric options. Remdesivir, an RNA polymerase inhibitor, has shown in vitro activity against SARS-CoV-2 and is currently under phase 3 trial.10 Investigational agents to combat the cytokine response, such as tocilizumab, an interleukin 6 (IL-6) receptor inhibitor, are being studied. Although the exact role of immunosuppression on the progression of COVID-19 is unknown, early case reports of kidney transplant recipients suggest minimizing immunosuppression while continuing steroidal therapy.11 Evaluation of clinical symptoms, utility of biomarkers, and progression of disease are important to understand for optimizing the management in COVID-19 positive SOT recipients. The effect of COVID-19 on the heart, lung, liver, pancreas, and kidney transplant organ systems is not well described. Herein, we present our experience with 21 consecutive SOT recipients diagnosed with COVID-19 at the Houston Methodist J.C. Walter Transplant Center followed to April 22, 2020.

BACKGROUND Excessive weight (EW) gain is common after solid organ transplantation, but there is little information concerning obesity after pancreas transplantation. The study goal was to characterize EW gain after kidney-pancreas (KP) transplantation. METHODS This was a retrospective single-center review of 100 KP recipients transplanted between September 2007 and June 2015. RESULTS The median percent weight gain for all recipients at 1 year posttransplant was 10% (interquartile range, 2.7%-19.3%) of baseline weight. EW gain, defined as greater than or equal to a 19% 1-year increase in weight, included all recipients (n = 26) above the upper limit of interquartile range for weight gain at 1 year. In multivariate analysis, recipient age

BACKGROUND This study reviewed the outcomes of a screening protocol for BK viremia to determine if early diagnosis, followed by immunosuppression minimization, would prevent progression to nephropathy and graft loss. METHODS This review included 369 renal transplant recipients tested for BK virus at serial time points after transplantation. Management included immunosuppression minimization plus cidofovir treatment for BK nephropathy. RESULTS Recipients received tacrolimus-based immunosuppression, with 8% prednisone-free and 6% who received desensitization. With a mean follow-up of 22 ± 10 months, 16% (n = 57) of recipients became BK viremia positive. The median (range) time to diagnosis was 3 (1-17) months. Because renal biopsy was performed selectively, 59% of recipients underwent biopsy, with 47% showing BK nephropathy. Seventy-four percent of recipients cleared the virus at a median (range) time of 9 (3-33) months, with four grafts lost to BK nephropathy. Cidofovir-treated recipients displayed a higher viral load at diagnosis but showed equivalent renal function at last evaluation. In multivariate analysis, recipient age, Asian ethnicity, deceased donor, and prednisone use were factors independently associated with BK viremia. Actuarial survival of BK-positive grafts was worse than that of BK-negative grafts (P

Background Malignancies, a well-known complication of immunosuppressive therapy in renal transplant recipients, represent an important cause of long-term morbidity and mortality. One approach to addressing this problem is identifying agents that display antineoplastic properties concomitant with their immunosuppressive effects. Methods We examined the neoplasms among 1008 renal transplant recipients treated at a single center with sirolimus-cyclosporine +/- prednisone. Results Clinical and laboratory data, including 62.3+/-26.1 months follow-up (range 27.1-131), revealed 36 tumors in 35 patients (3.6%) presenting at 32.5+/-29.8 months. The 2.4% incidence of skin tumors, the most common neoplasms, was 1.58-fold greater than the general U.S. population. In addition to a 0.4% incidence of posttransplant lymphoproliferative disorders (PTLD) and a 0.2% incidence of renal cell carcinomas, we observed single cases of breast, bladder, endometrial, lung, and brain neoplasms as well as leukemia. The mean trough drug concentrations at the time of diagnosis in affected recipients were within our putative target ranges. In addition to eleven graft losses due to death with a functioning kidney, two were related to chronic rejection following reduced immunosuppression, and one, therapeutic nephrectomy for PTLD. Five of twelve deaths were caused by malignancies; four others among 1008 patients over the entire follow-up were attributed to cardiovascular events; one, to respiratory failure; and two, at distant locations to unknown causes. Conclusions The sirolimus-cyclosporine +/- prednisone combination appears likely to be associated with a reduced incidence of tumors.

Background. We previously reported that the use of basiliximab together with sirolimus permits a window of recovery from delayed graft function before the introduction of reduced-dose cyclosporine. The present study reviews our experience with the substitution of thymoglobulin for basiliximab as induction therapy for recipients at increased risk for early acute rejection episodes. Methods. We retrospectively reviewed 145 cadaveric renal allograft recipients who received either basiliximab (n = 115) or thymoglobulin (n = 30) in combination with sirolimus and prednisone, followed by delayed introduction of reduced doses of cyclosporine. Recipients were stratified as high immune responders if they were African American, a retransplant recipient, or a recipient with a panel-reactive antibody greater than 50%. All other recipients were considered low immune responders. Results. Basiliximab-treated high immune responders exhibited a higher incidence of acute rejection episodes (26%) than either basiliximab-treated low immune responders (10%, P=0.04) or thymoglobulin-treated high immune responders (3%, P=0.01). The median time to initiation of cyclosporine was 12 days; cyclosporine was initiated when the serum creatinine level was 2.5 mg/dL or less. Patients with early return of renal function displayed a lower incidence of acute rejection episodes than those with later recovery of function (P=0.003). High immune responders treated with basiliximab expressed a higher mean serum creatinine level at 3 months (P

BACKGROUND We investigated a novel immunosuppressive protocol including thymoglobulin induction in combination with sirolimus and corticosteroids, followed by introduction of markedly reduced exposures to cyclosporine to prevent pancreas-transplant rejection. METHODS A 7-day course of thymoglobulin (1.5 mg/kg per day) was begun on postoperative day (POD) 0, together with 15 mg of sirolimus on POD 1, and followed by 5 mg per day, targeting these doses to achieve a trough of 10 to 20 ng/mL. When the serum creatinine was below 2.5 mg/dL, cyclosporine was introduced at 50 mg twice daily with dose adjustment to maintain a trough concentration of 100 to 125 ng/mL. RESULTS The 18 patients included 14 simultaneous pancreas-kidney and 4 pancreas-after-kidney transplant recipients. Two patients were African-American, three patients had a pretransplant panel reactive antibody greater than 20%, and the human leukocyte antigen (HLA) mismatch was 4.5+/-1 (mean+/-standard deviation). With a mean follow-up of 13.6+/-4.7 months, patient, kidney, and pancreas graft survivals are 100%, 100%, and 94%, respectively. A single pancreas graft was lost to thrombosis. There were no acute rejection episodes and no opportunistic infections. Mean hospital stay was 9+/-3 days. At 3 months posttransplantation, the mean value of serum creatinine was 1.2+/-0.3 mg/dL, fasting glucose was 88+/-15 mg/dL, and sirolimus dose at month 3 was 6.3+/-3 mg per day and at month 12 2.7+/-1 mg per day. The average total daily cyclosporine A dose at month 3 was 208+/-62 mg per day and 133+/-13 mg per day at 1 year. CONCLUSIONS This immunosuppressive regimen provided excellent prophylaxis against acute rejection with no opportunistic infections. We believe that careful monitoring of sirolimus and cyclosporine levels was critical to success of this protocol.

Background. Preemptive transplantation results in excellent patient and graft survival yet most transplant candidates are referred for transplantation after initiation of dialysis. The goal of this study was to determine barriers to preemptive renal transplantation. Methods. A nonvalidated questionnaire was administered to prospective kidney transplant recipients to determine factors that hindered or favored referral for transplantation before the initiation of dialysis. Results. One hundred ninety-seven subjects referred for a primary renal transplant completed the questionnaire. Ninety-one subjects (46%) had been informed of preemptive transplantation before referral, and 80 (41%) were predialysis at the time of evaluation. The median time from diagnosis of renal disease to referral was 60 months (range, 2Y444 months). In bivariate analysis, among other factors, knowledge of preemptive transplantation was highly associated (odds ratio=94.69) with referral before initiation of dialysis. Given the strong association between knowledge of preemptive transplantation and predialysis referral, this variable was not included in the multivariate analysis. Using multivariate logistic regression analysis, white recipient race, referral by a transplant nephrologist, recipient employment, and the diagnosis of polycystic kidney disease were significantly associated with presentation to the pretransplant clinic before initiation of dialysis. Conclusion. The principle barrier to renal transplantation referral before dialysis was patient education regarding the option of preemptive transplantation. Factors significantly associated with referral before dialysis were the diagnosis of polycystic kidney disease, white recipient race, referral by a transplant nephrologist, and employed status. Greater effort should be applied to patient education regarding preemptive transplantation early after the diagnosis of end-stage renal disease.

Background. Renal transplant recipients with de novo DSA (dDSA) experience higher rates of rejection and worse graft survival than dDSA-free recipients. This study presents a single-center review of dDSA monitoring in a large, multi-ethnic cohort of renal transplant recipients. Methods. The authors performed a nested case-control study of adult kidney and kidney-pancreas recipients from July 2007 through July 2011. Cases were defined as dDSA-positive whereas controls were all DSA-negative transplant recipients. DSA were determined at 1, 3, 6, 9, and 12 months posttransplant, and every 6 months thereafter. Results. Of 503 recipients in the analysis, 24% developed a dDSA, of whom 73% had dDSA against DQ antigen. Median time to dDSA was 6.1 months (range 0.2Y44.6 months). After multivariate analysis, African American race, kidney-pancreas recipient, and increasing numbers of human leukocyte antigen mismatches were independent risk factors for dDSA. Recipients with dDSA were more likely to suffer an acute rejection (AR) (35% vs. 10%, PG0.001), an antibody-mediated AR (16% vs. 0.3%, PG0.001), an AR ascribed to noncompliance (8% vs. 2%, P=0.001), and a recurrent AR (6% vs. 1%, P=0.002) than dDSA-negative recipients. At a median follow-up of 31 months, the deathcensored actuarial graft survival of dDSA recipients was worse than the DSA-free cohort (P=0.002). Yet, for AR-free recipients, there was no difference in graft survival between cohorts (P=0.66). Conclusions. Development of dDSA was associated with an increased incidence of graft loss, yet the detrimental effect of dDSA was limited in the intermediate term to recipients with AR.

Background. Cytotoxic T-lymphocyte antigen 4 (CTLA4) has been shown to play a critical role in the down-regulation of the immune response. We retrospectively examined the association between acute rejection and two polymorphisms in the CTLA4 gene, the dinucleotide (AT) n repeat polymorphism in exon 3 and the single nucleotide polymorphism A/G at position 49 in exon 1, in a cohort of liver and kidney transplant recipients. Methods and Results. A total of 207 liver and 167 renal transplant recipients were analyzed. In the case of the (AT) n repeat polymorphism we found an increased incidence of acute rejection in association with allele 3 and 4 in both liver and kidney (P=0.002 and 0.05, respectively). In addition, in liver transplant recipients, allele 7 was associated with acute rejection independent of ethnicity (P

Background. We investigated whether recipients of living donor grafts who suffer an acute rejection progress to graft loss because of chronic rejection at a slower rate than recipients of cadaveric grafts. Methods. A retrospective review was made of 296 renal transplantations performed at Mount Sinai Hospital. Only grafts functioning for at least 3 months were included in this analysis. Demographic variables of donor and recipient age, race, sex, and serum creatinine at 3 months after transplantation were compared between groups. Results. Among the acute rejection-free cohort, the estimated 5-year graft survival was 90% for those receiving transplants from living relatives and 88% for those receiving cadaveric transplants (P=0.76). However, in grafts with early acute rejection, the 5-year survival was 40% for cadaveric recipients compared with 73% for living related graft recipients (P

Background. The pathogenesis of chronic rejection likely involves an interplay between immunogenic and nonimmunogenic factors. The objective of this study was to determine the influence of cold ischemic preservation injury on the rate of progression to chronic rejection in the Lewis to F344 cardiac allograft model. Methods. To induce an ischemic injury, donor hearts were stored for 3 hr at 4°C in University of Wisconsin solution before transplantation. Allografts were excised at 1, 7, and 90 days after transplantation or at rejection. Vasculopathy was graded for degree of inti-mal thickening based on the involvement of vascular perimeter and luminal compromise. Results. The degree of vessel injury in ischemic injured allografts at 90 days was significantly greater than in nonischemic injured allografts (2.8±0.4 vs. 1.6±0.5, P

Mouse mAbs directed against the alpha/beta-TCR were tested in clinical phase II and in triple-blind, randomized phase III studies. A clinical phase II trial administered 50 mg of murine anti-human alpha/beta-TCR mAb (BMA 031) intravenously on the day of, as well as 2 and 4 days after, cadaveric donor renal transplantation in combination with a CsA/prednisone regimen. None of 12 patients showed even moderately adverse side effects. A phase III, triple-blind randomized trial enrolled 24 patients in the BMA 031 group and 22 patients in a placebo control group. BMA 031 treatment significantly reduced the incidence of rejection events within the first 10 posttransplant days to 1 patient versus 9 episodes in the placebo group (P < 0.01). By the end of 30 days, 6 rejection episodes had occurred in the BMA 031 group and 11 in the control cohort (P = NS). After a minimum of 30 months follow-up, the actual allograft survival rate was 87% in the BMA-treated group compared with 68% in the control cohort.

A mouse IgG1 mAb (R73) directed against the rat alpha/beta-TCR was documented not only to prolong the survival of allografts across major RT1 plus non-RT1 antigenic disparities, but also to display a synergistic immunosuppressive interaction with CsA. Heterotopic cardiac transplants from Buffalo (RT1b) rats survived significantly longer in Wistar-Furth (RT1u) hosts treated immediately after the operation with 0.25 mg/kg R73 i.v., with a mean survival time of 11.0 +/- 5.5 versus 6.8 +/- 1.2 days in the untreated group (P < 0.01). Administration of 0.5 or 5.0 mg/kg R73 displayed dose-dependent prolongation of survival to 17.0 +/- 8.3 days (P < 0.05) or 28.6 +/- 14.0 days (P < 0.01), respectively. One 0.5 mg/kg i.v. dose of R73 delivered to normal Wistar-Furth hosts produced peripheral T cell depletion that reversed after 16 days. Three injections of 0.5 mg/kg R73 on days 0, 2, and 4 prolonged allograft survival to 52.5 +/- 38.6 days compared with 17.0 +/- 8.3 days with a single dose (P < 0.01). Addition of 3 daily doses of 5 or 10 mg/kg CsA administered per oral gavage to a single dose of 0.05, 0.25, or 0.5 mg/kg R73 injected on day 0 produced a synergistic effect to prolong allograft survival, as determined by the rigorous median-effect analysis. The synergistic interaction, which may be explained by the inhibitory effect of CsA on Ca(2+)-dependent pathways triggered after activation of TCR, the target of R73, warrants clinical investigation in order to assess the potential impact of anti-alpha/beta-TCR mAb on CsA-based immunosuppressive regimens.

BACKGROUND Previously transplanted patients are more likely to be sensitized, leading to prolonged waitlist times and decreased graft survival. This analysis of the United Network for Organ Sharing kidney/pancreas transplant database investigates factors at the time of first transplant associated with increased sensitization in patients undergoing second transplantation. METHODS Records of nonsensitized patients (panel reactive antibodies [PRA]

Pretransplant test-dose pharmacokinetic profiles were used to determine individual cyclosporine drug bioavailability and clearance rates in renal transplant patients. Assuming a linear relation between dose and area under the concentration curve (AUC), starting i.v. and p.o. CsA doses were computed from the test-dose results. Target values were 400 ng/ml steady-state concentration (Css) during continuous intravenous infusion, and 500 ng/ml average drug concentration (Cavss = AUC/dosing interval) after oral administration, based upon measurements with the specific monoclonal antibody 3H-tracer radioimmunoassay. The outcomes after dose individualization with a 1-(n = 32), 2-(n = 38), or 3-(n = 41) hr i.v. infusion test dose and a p.o. test dose (n = 111) were compared with 228 historical control patients who received a uniform protocol of CsA i.v. at 2.5 mg/kg/day and p.o. at 14 mg/kg/day. The observed Css after i.v. CsA was within 10% of the target concentration in 73% of recipients tested with the 3-hr protocol, a significantly greater fraction than achieved with either the uniform dose (14%), or the 1-(34%) and 2-(25%) hr protocols. Patients in the 3-hr protocol group showed reduced incidences of delayed graft function, early graft loss, and rejection episodes, and a lower mean serum creatinine value, particularly at 7 but also at 30 days posttransplantation. Administration of the predicted oral dose produced a peak concentration of greater than or equal to 700 ng/ml drug absorption in 60% of recipients at 3 days, 90% at 5 days, and 98% at 7 days. The test-dose method less effectively predicted the appropriate oral CsA dose to produce target Cssav and failed to reduce the 90-day rejection incidence. Despite its limitations with the more-complicated p.o. route, the test-dose method successfully predicts i.v. CsA doses, thereby reducing the incidence of early adverse events.

Background. We evaluated the impact of reduced nephron mass on nephrotoxicity by cyclosporine A (CsA) and/or sirolimus (SRL). Methods. Renal function was tested in salt-depleted rats bearing two kidneys (2K), one kidney, or half a kidney (1/2K) and treated for 7 or 28 days with CsA (5 mg/kg) and/or SRL (0.8 mg/kg). We also measured the expression of aquaporin-2, sodium/phosphate cotransporter (NaPi)-2, paracellin-1, and kidney injury molecule (KIM)-1 by real-time polymerase chain reaction. Results. At 7 days in 2K, serum creatinine clearance (CrCl) was decreased only in CsA/SRL-treated group (P

BACKGROUND Because the course of polyoma virus-associated nephropathy (PVAN) has not been evaluated in a large cohort of patients receiving sirolimus (SRL)-based regimens, we have herein presented the incidence, clinical characteristics, and outcomes of 378 renal transplant recipients treated with SRL-based immunosuppression. METHODS This retrospective single center study evaluated 344 kidney alone (KTX) and 34 simultaneous pancreas-kidney (SPK) transplantations performed between June 2000 and December 2004. RESULTS At a mean follow-up of 43.3 months, six kidney (1.7%) and three kidney-pancreas (9.0%) transplanted patients displayed biopsy-proven PVAN. The mean time to diagnosis after transplantation was 18.2 months (range: 3.5-31.1 months), with a higher incidence among patients exposed (4.23%) versus not exposed to rabbit antithymocyte globulin (rATG; 0.53%; P=0.019) or SPK (9.0%) versus KTX (1.7%) recipients (odds ratio: 5.43; confidence interval: 1.29-22.8; P=0.038). Despite treatment with cidofovir, reduced immunosuppression and maintenance therapy with no agents other than SRL (C0=10.2+/-2.7 ng/dL) plus modest doses of prednisone (< or =5 mg), five patients (55.5%) experienced renal allograft failure. No rejection episodes were documented during the PVAN treatment and pancreatic function continued to be excellent among the SPK patients. CONCLUSIONS Patients treated with SRL-based immunosuppression showed an incidence at the lower end of the range described with various other contemporaneous immunosuppressive regimens and with other cohorts not undergoing BK virus polymerase chain reaction surveillance. Exposure to rATG and SPK transplantation represented risk factors for the occurrence of PVAN, which showed a pernicious course despite withdrawal of calcineurin antagonists and/or mycophenolate mofetil.

This study aims to determine the impact of thymoglobulin-sirolimus-cyclosporine immunosuppression on the alloimune response of pancreas-kidney transplant recipients.Thirty-six pancreas transplant recipients received an induction protocol of thymoglobulin, sirolimus, reduced-dose cyclosporine, and corticosteroids. Ten recipients were also enrolled in a study to measure immune responsiveness. Flow PRA determined HLA antibody, donor-specific flow cytometry crossmatching (FCXM), T-cell subset, and suppressor cell assays were performed during the first posttransplant year.One-year patient, kidney, and pancreas graft survivals were 97%, 94%, and 92%, respectively. There was one death and three graft losses. There were no acute rejection episodes. Recipients in the immune-monitoring study (n=10) displayed80% depression of CD3, CD4, and CD8 (+) cell counts up to 3 months posttransplant. At transplantation 9/10 patients displayed10% class I and no class II HLA antibody. By 3 months, 7/10 monitored recipients showed a transient elevation in class I HLA antibodies, including 2 patients who expressed80% Flow PRA. One patient was pretransplant FCXM positive, whereas by 3 months posttransplant 2/10 patients demonstrated a positive FCXM. There were no clinical consequences of the presence of HLA antibody or the positive FCXMs. By 6 months, 7/9 patients demonstrated immunoregulatory suppressor cells.The absence of acute rejection events was likely due to inhibition of donor-specific immunity by the immunosuppressive regimen. Seventy percent of patients demonstrated an early, non-donor-directed HLA antibody response that had no adverse effect on graft function and 78% of the monitored patients displayed immunoregulatory cells probably contributing to the successful outcomes.

The effects of a subtherapeutic regimen of rapamycin (RAPA) combined with CsA and donor-specific blood transfusions (DST) were investigated in the ACI to LEW cardiac allograft model. Three protocols were studied. In protocol 1, recipients received a DST (day -1), RAPA intravenously at 0.08 mg/kg/day (day -1 to +5), and CsA intramuscularly at 5 mg/kg/day (day -1 to +1). In protocol 2, the course of CsA was extended to day +5, and in protocol 3 the treatment was further modified to include a second DST on day +3. Control groups received drug treatments alone or combined with DST or third-party blood transfusions. In all protocols, RAPA, CsA, or DSTs alone had little or no effect on graft survival. RAPA-DST or CsA-DST also had no effects beyond the ones induced by the drugs alone. In the RAPA-CsA groups, graft survivals were similar to the ones obtained with CsA alone. In contrast, in each of the protocols, the RAPA-CsA-DST treatment resulted in significant prolongation of graft survival as compared with all controls (P < 0.05). The administration of a second DST (CsA-RAPA-DSTx2) provided no additional benefits over a single DST. Lymph node cells from CsA-RAPA-DST subjects were hyporesponsive in MLR against donor cells and suppressed the proliferation of normal LEW cells in an MLR coculture assay, suggesting the presence of suppressor cells. Furthermore, in the CsA-RAPA-DST group, the anti-donor antibody response was suppressed. These data demonstrate that RAPA, CsA, and DST interact positively by inducing a clear-cut and significant prolongation of allograft survival in the rat model under conditions in which the individual components of the treatment are essentially ineffectual.

Although the introduction of cyclosporine-prednisone immunosuppression has improved early renal graft survival, chronic rejection remains a major cause of longterm graft dysfunction. This study retrospectively examined 69 cases of chronic rejection among 643 primary renal allograft recipients treated with cyclosporine-prednisone immunosuppression from July 1981 to October 1989. Chronic rejection was defined as a rejection episode diagnosed greater than 90 days posttransplantation with characteristics of progressive nonacute renal function deterioration, confirmed, in most cases, by renal biopsy. This group was compared with an equal-sized matched cohort. Among cadaveric recipients, 61 of 456 patients (13.4%) displayed chronic rejection, whereas among living-related recipients, 8 of 187 patients (4.3%) developed chronic rejection. The average time from the date of transplantation to diagnosis of chronic rejection was 15 +/- 14 months. One- and three-year graft survivals following diagnosis of chronic rejection were 51% (30/59) and 25% (13/51), respectively, compared with the cohort one- and three-year graft survivals of 98% (58/59) and 86% (32/37) at similar periods posttransplantation. HLA mismatch, PRA status, blood transfusion history, lipid levels, cyclosporine trough levels, incidence of prior acute rejection, and initial graft dysfunction were not significantly different between the chronic rejection group and the matched cohort. Hypertension and proteinuria were significantly associated with chronic rejection (P less than 0.001). Of 58 biopsies performed, findings solely consistent with chronic rejection were observed in 9 cases (15%) and "acute upon chronic" rejection in 49 cases (83%). Treatment of acute concomitants improved the renal function in 43% (27/63) by the time of hospital discharge. Nonetheless, at 12 months the incidence of improved renal function eroded to 22% (13/59), suggesting that the benefit was relatively short-lived. Although the overall incidence of chronic rejection in this group of cyclosporine-prednisone-treated patients was lower than previous azathioprine-prednisone cohorts, the clinical presentation and progression of chronic rejection was similar. Additionally, the incidence of chronic rejection within this series was lower among living-related recipients versus cadaveric recipients of donor organs.