Selective corticosteroid and calcineurin-inhibitor withdrawal after pancreas-kidney transplantation utilizing thymoglobulin induction and sirolimus maintenance therapy.

Of 25 simultaneous pancreas-kidney transplant (SPK) recipients treated with thymoglobulin induction, sirolimus and reduced-dose cyclosporine (CsA), 18 low-immune responders (non-African-Americans, PRA < 30%) were withdrawn from prednisone on post-transplant day 5, whereas seven high-immune responders continued on prednisone. Most high- and low-immune responder recipients were converted from CsA to mycophenolic acid (MPA) at six months post-transplantation. At a mean follow-up of 28 +/- 10 months, two pancreas grafts were lost to pancreatitis. There were no patient or kidney graft losses, but one acute rejection episode. At 28 +/- 11 months, all 18 low-responder recipients remain steroid-free. Twenty recipients (14 low and six high-immune responders) were converted from CsA to MPA. During conversion, immune response was monitored by Flow-PRA and T-cell stimulation (Cylex) assays. Nineteen of 20 recipients displayed a post-conversion PRA of 0%, whereas one highly sensitized patient expressed a post-conversion PRA of 67%. Fifty-eight percent of individual T-cell stimulation scores were in the hypo-responsive range. Twelve of 18 low-immune responders are both steroid and CsA-free at a mean follow-up of 17 +/- 13 months, whereas five of seven high-immune responders remain CsA-free at a mean follow-up of 11 +/- 10 months. These data suggest that thymoglobulin induction with combined sirolimus and CsA maintenance therapy permits immunosuppression minimization in selected SPK recipients.

DRB1*1613N: a novel DRB1 allele with a premature termination codon.

DRB1 null alleles are extremely rare and always sporadic, suggesting their biological selective disadvantage.

A pilot study of immunosuppression minimization after pancreas-kidney transplantation utilizing thymoglobulin induction and sirolimus maintenance therapy.

AIMS: To determine outcomes utilizing thymoglobulin and sirolimus immunosuppression, with early steroid withdrawal in low-immune responder pancreas-kidney (SPK) recipients, and conversion from cyclosporine (CsA) to mycophenolic acid (MPA) in all recipients at 6 months posttransplantation. METHODS: SPK recipients received thymoglobulin, sirolimus, and reduced-dose CsA immunosuppression. Low immune responders (non-African-Americans with a pretransplant PRA < 30%) were withdrawn from prednisone on posttransplant day 5 and high immune responders were continued on prednisone. All recipients were converted from CsA to MPA at 6 months posttransplantation. During conversion, recipient immune response was monitored by flow PRA and a T-cell stimulation assay (Cylex). RESULTS: With a mean follow-up of 9 +/- 4 months, one pancreas was lost to pancreatitis, with no patient or kidney losses and no acute rejection episodes. All eight low immune responder patients were steroid-free at 9 +/- 5 months posttransplantation. Seven patients (five low and two high immune responders) with at least 6-month follow-up were converted from CsA to MPA. One high immune responder with a pretransplant PRA of 43% remained with a PRA of 53% +/- 2% postconversion. The second high immune responder had a pretransplant PRA of 34% and a postconversion PRA of 0%. The five low immune responders had a mean pretransplant PRA of 16% +/- 15% and a postconversion PRA of 0% (P < .01). The Cylex assay resulted in 67% low responsiveness for both high and low immune responders. CONCLUSION: Thymoglobulin induction with sirolimus maintenance therapy permitted immunosuppression minimization in selected pancreas transplant recipients. Posttransplant evaluation revealed a diminished (regulated) immune response in six of seven patients.

Graft survival and immune regulation of pancreas allograft recipients induced with thymoglobulin, sirolimus, and cyclosporine.

BACKGROUND: Our objective was to determine the impact of thymoglobulin-sirolimus-cyclosporine immunosuppression on the alloimmune response of pancreas-kidney transplant recipients. METHODS: Thirty-six pancreas transplant recipients received an induction protocol of thymoglobulin, sirolimus, reduced-dose cyclosporine, and corticosteroids. A subset of 10 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 at various timepoints during the first posttransplant year. RESULTS: One-year patient, kidney, and pancreas survivals were 97%, 94%, and 92%, respectively. There was 1 death due to sepsis, and 1 kidney and 2 pancreas graft losses. There were no acute rejection episodes. Recipients in the immune-monitoring study displayed depression of CD3, CD4, and CD8 counts (<80%) until 3 months posttransplant. At transplantation, 9 of 10 patients displayed <10% class I HLA antibody. By 3 months, 7 of 10 showed a transient elevation in class I HLA antibodies, with 2 patients expressing >80% flow PRA. At transplant 1 patient was FCXM-positive, whereas, by 3 months posttransplant, 2 of 10 patients demonstrated a positive FCXM. There were no clinical consequences to either the presence of HLA antibody or the positive FCXMs. By 6 months, 7 of 9 patients expressed immunoregulatory suppressor cell activity. CONCLUSIONS: The absence of acute rejection events was likely due to inhibition of donor-specific immunity. 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 patients displayed immunoregulatory suppressor cell function, probably contributing to the successful clinical outcome.

Transplantation of single pediatric kidneys into adult recipients.

AIM: To evaluate the outcome of single pediatric kidneys transplanted into adult recipients. METHODS: A retrospective single-center review was performed of transplants from donors less than 5 years of age. Outcomes were compared with recipients of grafts from donors 18 to 45 years transplanted during the same time period. RESULTS: Thirty single renal transplants from pediatric donors and 117 transplants from adult donors between 18 and 45 years of age were performed during the study period. The mean age of the pediatric donors was 2.9 +/- 0.8 years versus 31.5 +/- 8.9 years for adult donors (P < .001). The mean age of the recipients of pediatric donors was 41.9 +/- 13 years versus 48 +/- 12.6 years for recipients of adult grafts (P = .020). The mean recipient weight of pediatric donors was 55.9 +/- 7.8 kg versus 78.0 +/- 17.7 kg for recipients of adult donors (P < .001). Sixty-six percent of pediatric donor recipients were of female gender compared to only 36% of adult donor recipients (P = .005). Death-censored actuarial graft survivals at 1 and 4 years for recipients of pediatric donor grafts were 90% and 85% compared to 93% and 85% for recipients of adult donor grafts (P = NS). The mean calculated creatinine clearances of adult donor graft recipients at 1 and 4 years posttransplantation were 70.8 +/- 26.5 and 73.7 +/- 27.2 mL/min, respectively, compared to 50.3 +/- 20.1 and 56.3 +/- 21.4 mL/min for pediatric donor grafts (P < .01 at 1 and 4 years). CONCLUSION: The use of single pediatric donor kidneys provides an excellent opportunity to safely expand the donor pool.

The effect of pancreas transplantation on peripheral vascular disease complications.

BACKGROUND: We sought to determine whether pancreas transplantation reduced the incidence of peripheral vascular complications in diabetics with renal insufficiency. METHODS: A retrospective single-center review was done of 36 kidney-pancreas (KP) and 88 kidney-alone (KA) recipients with a diagnosis of diabetes and end-stage renal disease (ESRD) transplanted between May 1997 and July 2002. Risk factors studied included type of transplant, age, gender, history of smoking, coronary artery disease, hypertension, and peripheral vascular disease (PVD). The endpoint was first peripheral vascular event occurring after transplantation, defined as either an amputation or revascularization procedure. RESULTS: The mean age of the cohort was 51 +/- 9 years, 64% of patients were of male gender, 20% with a history of smoking, 98% with hypertension, 15% with coronary artery disease (CAD), and 12% with a history of PVD. With a median follow-up of 45 months (12 to 79 months), 3/36 (8%) of KP recipients suffered a PVD complication, compared to 10/88 (11%) of KA recipients (P = NS). Similarly, age, gender, a past history of smoking, CAD, and hypertension were not predictive of PVD complications. Five of 15 patients (33%) with a pretransplant history of PVD suffered a postoperative PVD event compared to only 8 of 109 patients (7%) with no prior history of PVD (P =.008). CONCLUSIONS: Restoration of normoglycemia by pancreas transplantation did not reduce the risk of PVD complications in diabetics with renal failure. A pretransplant history of PVD was the only risk factor associated with posttransplant PVD events.

Initial results of solitary pancreas transplants performed without regard to donor/recipient HLA mismatching.

BACKGROUND: We hypothesized that solitary pancreas transplants could be performed successfully even in the presence of poor HLA matching if an aggressive approach were taken with regard to immunosuppressive protocol and the performance of allograft biopsy. METHODS: Seven pancreas-after-kidney transplants and seven pancreas transplants alone were performed without consideration given to the degree of HLA mismatching (MM) using tacrolimus (FK506)/mycophenolate mofetil (MMF)/prednisone maintenance therapy. Mean (+/-SD) total HLA MM was 4.8+/-1.2. All patients were followed for at least 6 months. The first four cases were induced with ATGAM for 7 to 10 days. In the remaining 10 cases, an ultrasound-guided percutaneous needle biopsy was attempted on a protocol basis 10 days after completing induction with OKT3 for 7 (n=2) or 14 (n=8) days. RESULTS: Overall patient survival, graft survival, and incidence of acute rejection requiring treatment were 86, 79, and 50%, respectively. Two patients receiving ATGAM developed grade III-IV rejection at 3 weeks. Both patients receiving OKT3 for 7 days developed early grade III rejection. However, only three of eight patients receiving OKT3 for 14 days developed rejection requiring treatment. Protocol biopsy was successfully performed in six of seven patients and uncovered three cases of otherwise undetectable grade III-IV rejection. CONCLUSIONS: Although based on a small number of cases, our results suggest that solitary pancreas transplants with a poor HLA match can be performed with an acceptable rejection incidence and graft survival rate using an OKT3/FK506/MMF/prednisone regimen with protocol biopsy.

Flow cytometry-detected IgG is not a contraindication to renal transplantation: IgM may be beneficial to outcome.

BACKGROUND: At our transplant center, primary recipients of either a haplo-identical (haplo-ID) living related (LRD) or a cadaveric (CAD) donor renal allograft are transplanted after a negative donor-specific IgG anti-human globulin (AHG) cross-match (XM). Testing included the historically highest panel-reactive antibody and the immediate (0-7 days) pretransplant sera. A positive donor specific IgM-AHG XM has not been a contraindication to transplant. Reports suggest that donor-specific flow cytometry cross-matches (FCXM) may be more clinically informative than the AHG-XM. METHODS: We therefore evaluated the impact of a positive FCXM (IgG or IgM) on the rejection frequency (0-12 months after transplant) and 1-year graft survival for cyclosporine-prednisone-treated primary (haplo-ID and CAD) renal allograft recipients. All transplants were performed after a negative donor-specific IgG AHG-XM regardless of the IgM-AHG XM status. RESULTS: Rejection frequencies (26% vs. 31%, P = NS) and 1-year graft survivals (92% vs. 89%, P = NS) were comparable for haplo-ID LRD FCXM-negative and IgG-FCXM-positive recipients. However, IgM-FCXM-positive LRD recipients experienced significantly fewer rejections (13% vs. 26% P<0.02) and an improved 1-year graft survival (100% vs. 92%, P<0.02) than FCXM-negative LRD recipients. Similar results were observed for primary CAD recipients. Rejection frequencies (40% vs. 44%, P = NS) and 1-year graft survivals (83% vs. 81%, P = NS) were comparable for primary CAD FCXM-negative and IgG-FCXM-positive recipients. Again, IgM-FCXM-positive primary CAD recipients experienced significantly fewer rejections (22% vs. 40%, P<0.02) and improved 1-year graft survivals (89% vs. 83%, P<0.05) than FCXM-negative recipients. CONCLUSION: These data suggest that, after a negative donor-specific IgG-AHG XM, an IgG-positive FCXM is not a contraindication to transplantation. The presence of IgM may be beneficial in reducing the occurrence of rejection episodes and improving graft survivals.

Comparison of PRA-STAT, sHLA-EIA, and anti-human globulin-panel reactive antibody to identify alloreactivity in pretransplantation sera of heart transplant recipients: correlation to rejection and posttransplantation coronary artery disease.

BACKGROUND: Screening pretransplantation recipient sera for percent panel reactive antibodies (%PRA) by an anti-human globulin (AHG) assay may identify recipients who are at risk for graft rejection or development of posttransplantation coronary artery disease. However, the pretransplantation AHG-%PRA does not always correlate with the occurrence of graft rejection or coronary artery disease. METHODS: We compared the predictive capacity of the AHG-%PRA with that of an enzyme-linked immunoassay (EIA)-based PRA assay that identifies immunoglobulin G bound to soluble human leukocyte antigen (sHLA) class I molecules from pooled platelets of 240 random donors (sHLA-EIA), and that of an EIA-based assay that detects immunoglobulin G anti-HLA class I antibodies bound to sHLA derived from individual HLA-typed cell cultures (PRA-STAT). The pretransplantation sera from 130 cardiac allograft recipients were comparatively tested and results evaluated. RESULTS: Although AHG-%PRA- and sHLA-EIA-determined PRA results were comparable, neither assay discriminated potential recipients at risk for rejection or coronary artery disease. However, cardiac allograft recipients with pretransplantation PRA-STAT sera > 10% were at risk for (1) graft rejection (77% vs 56%, p < .05); (2) more rejections/recipient (1.9 vs 1.0, p < .02); (3) graft rejection within 30 days (92% vs 38%, p < .001); or (4) development of coronary artery disease (48% vs 23%, p < .05) than recipients with pretransplantation PRA-STAT sera < 10%. CONCLUSIONS: PRA-STAT analysis of pretransplantation sera from potential cardiac allograft recipients may be more clinically informative about HLA alloimmunity and a better predictor of adverse clinical events than either AHG-%PRA- or sHLA-EIA-determined PRA.

Comparison between enzyme-linked immunosorbent assay and cytotoxic cross-match procedures for detecting IgG anti-donor antibodies.

BACKGROUND: Disadvantages inherent to complement-dependent cytotoxicity cross-match (CDC XM) methods are the requirements for complement and viable target cells, detection of antibodies (Abs) against non-HLA antigens, and subjective scoring. Cross-Stat (SangStat Medical Corp., Menlo Park, CA), a recently developed enzyme-linked immunosorbent assay XM procedure for the detection of IgG anti-donor HLA Abs, is theoretically devoid of these flaws. METHODS: We compared results of Cross-Stat and our standard anti-human globulin (AHG)-enhanced CDC XM procedure on 524 sera from 230 transplant candidates, which were evaluated against 51 cadaveric donors. RESULTS: There was a significant correlation between AHG-CDC IgG XM and Cross-Stat results (P<0.001). For false negative sera, repeat AHG-CDC IgG XMs were still positive after platelet absorption, indicating that the Abs present were either non-HLA Abs or anti-HLA class II. Flow cytometry testing of false positive sera usually (42/62) substantiated Cross-Stat results, indicating that the discrepancy with AHG-CDC IgG XM is caused by greater sensitivity of Cross-Stat. Relative to the AHG-CDC XM, the sensitivity of Cross-Stat was 100%, the specificity was 93%, the positive predictive value was 73%, and the negative predictive value was 100%. A technical shortcoming of the Cross-Stat assay is that the frequency of indeterminate samples in the assays was 15%. Among 49 Cross-Stat negative vs. 13 Cross-Stat positive primary cadaveric renal allograft recipients (all AHG-CDC IgG-XM negative), there was no statistical difference in overall graft survival. CONCLUSION: Given the important theoretical advantages of enzyme-linked immunosorbent assay-based XM methods over the CDC XM, however, further testing of the clinical relevance of the Cross-Stat is warranted.

Can an immunologically, nonreactive potential allograft recipient undergo transplantation without a donor-specific crossmatch?

Performance of the pretransplant crossmatch requires 4 or more hours . Delays in the crossmatch might alter operating room availability and thereby increase donor organ cold ischemia time that might then result in increased risk of delayed graft function. To avoid these problems, recipients could be identified who would be expected to display negative donor crossmatches and who could be transplanted with a concurrent or retrospective rather than a pretransplant crossmatch. We, therefore, evaluated the percent reactive antibodies and donor IgG-antihuman globulin (AHG) crossmatch results of 1165 sera from 220 potential allograft recipients. Twenty-five (11%) of 220 recipients consistently displayed a 0% PRA and, with only one exception, their sera (n= 156) tested IgG-AHG crossmatch-negative against potential cadaveric donors (a 0.6% IgG-AHG positive crossmatch risk). These data suggest that the timing of the pretransplant serum crossmatch could be altered for a highly selected group of immunologically nonreactive recipients.

T cell-T cell activation in multiple sclerosis.

Activated T cells are able to stimulate proliferation in resting T cells through an antigen non-specific mechanism. The in vivo usefulness of this T cell-T cell activation is unclear, but it may serve to amplify immune responses. T cell-T cell activation could be involved in the well-documented occurrence of multiple sclerosis (MS) exacerbations following viral infections. Excessive activation via this pathway could also be a factor in the etiology of MS. We tested the hypothesis that excessive T cell-T cell activation occurs in MS patients using in vitro proliferation assays comparing T cells from MS patients to T cells from controls. When tested as responder cells, T cells from MS patients proliferated slightly less after stimulation with previously activated cells than T cells from controls. When tested as stimulator cells, activated cells from MS patients stimulated slightly more non-specific proliferation than activated cells from controls. Neither of these differences were statistically significant. We conclude that T cell proliferation in response to activated T cells is similar in MS and controls.

Clinical relevance of anti-HLA antibodies pre and post transplant.

Pretransplant histocompatibility testing seeks to select compatible donor-recipient pairs for transplantation. Sera from prospective renal transplant recipients are screened for the presence of human leukocyte antigen (HLA) antibodies to determine humoral alloimmunization. Present techniques screen patient sera using a complement-dependent cytotoxicity assay and express the results as percent of panel reactive antibody (PRA). However, the standard assay suffers because it needs viable target cells, a variable sensitivity of cells for complement, subjective evaluation, a lack of standardized methodology, and a variable correlation with clinical outcomes. Alternatively, an enzyme-linked immunosorbent assay (ELISA) methodology can detect IgG anti-HLA reactivity based on the binding of immunoglobulin to soluble HLA class I antigens. This method provides increased objectivity and reproducibility, does not require use of viable target cells, and most importantly, detects immunoglobulin that is reactive to HLA class I antigens. Data discussed herein suggest that identifying reactive recipient sera using the enzyme-linked immunosorbent assay (ELISA) (PRA-STAT, Sang Stat Med, Menlo Park, CA) methodology may be more informative clinically than current standard percent of panel reactive antibody (PRA) assays.

Ingested IFN-alpha has biological effects in humans with relapsing-remitting multiple sclerosis.

Parenterally administered human recombinant type I interferons (hrIFN) in relapsing-remitting multiple sclerosis (RRMS) decrease relapses and spontaneous in vitro IFN-gamma production, reduce clinical progression, and decrease magnetic resonance imaging (MRI)-defined disease activity and lesions. Parenterally administered type I IFN use is limited by clinical and chemical toxicities, and the induction of antibodies that abrogate their activity in vivo correlated with the loss of clinical benefit. Therefore, we determined whether ingested IFN-alpha was non-toxic and had biological effects in humans. Ingested hrIFN-alpha showed no toxicity in normal volunteers or patients with RRMS at doses ranging from 300 to 100,000 units. In subjects with RRMS, a significant decrease in Con A-mediated proliferation and serum soluble intercellular adhesion molecule-1 (sICAM-1), a surrogate measure for disease activity in MS, was found after ingesting 10,000 and 30,000 units IFN-alpha The RRMS subjects also showed decreased IL-2 secretion after ingesting 10,000 units IFN-alpha and decreased IFN-gamma, TGF-beta and IL-10 production after ingesting 30,000 units IFN-alpha. The decreased secretion of IFN-gamma and IL-2 by ingested IFN-alpha suggests that oral IFN-alpha may cause a functional inhibition of Th J-like T helper cells in RRMS, a potential site of intervention at the level of effector T cells in MS. Our studies support the oral use of human IFN-alpha as a biological response modifier in humans.