Transplant nephrectomy after allograft failure is associated with allosensitization.

OBJECTIVES: To evaluate the effect of transplant nephrectomy (TN) on the percentage of panel reactive antibody (%PRA) and donor-specific antibody (DSA) levels in patients with renal allograft failure. METHODS: The records of patients with failed kidney transplants, who had undergone TN from 2000 to 2007, were reviewed. The pre- and post-TN serum samples were available for analysis from 31 patients. Human leukocyte antigen typing and the %PRA was measured in these patients using standard serologic techniques. The pre- and post-TN patient serum samples were evaluated for DSA levels using solid phase assays and single antigen beads. The pre- and post-TN measurements of the %PRA and DSA levels were compared using the Wilcoxon signed rank test, and the associated clinical variables were identified on multivariate regression analysis. RESULTS: The mean %PRA increased from 33.4 to 75.6 for class I antigens (P < .001) and from 38.9 to 60.6 (P = .002) for class II antigens in patients before and after TN, respectively. This increase was associated with an increase in the mean human leukocyte antigen class I and class II DSA levels from 33,518 molecular equivalents of soluble fluorochrome (MESF) to 121,457 MESF (P < .001) and from 45,459 MESF to 126,968 MESF (P < .001), respectively. Regression analysis showed that rejection episodes and an interval from graft failure to TN of <10 months were associated with greater increases in the mean %PRA (P < .001) and mean DSA levels (P = .02). CONCLUSIONS: The results of the present study have confirmed that the %PRA increases after TN in patients with renal allograft failure, and sensitization occurs after TN, with an increase in DSA levels. Rejection episodes and early TN after graft failure might result in a greater degree of sensitization.

Predictors of acute rejection after lung transplantation.

BACKGROUND: Acute rejection (AR) after lung transplantation (LTx) impacts survival and quality of life. The objective of this study, therefore, was to identify risk factors for AR after LTx, focusing on donor- and recipient-specific factors, operative variables, and immunologic issues, including pretransplant panel-reactive antibody (PRA) levels, and donor-recipient human leukocyte antigen (HLA) mismatch. METHODS: From March 1996 to November 2007, 481 adults undergoing LTx had 3237 serial transbronchial biopsy specimens that were evaluated for perivascular rejection (grade A0 to A4). Longitudinal analysis was used to characterize the prevalence of rejection grade and influence of donor, recipient, technical, and immunologic variables. RESULTS: AR was highest (54%≥A1) in the first 2 months after LTx, decreased at 6 months (16%≥A1), then remained steady. Prevalence of AR at any time was dominated by donor-specific factors of young age (p<0.0001), blunt trauma (p=0.008), and nonblack race (p=0.012) and by recipient class II PRA exceeding 10% (p=0.005). AR within 2 months was associated with HLA mismatch at the DR locus (p=0.0006) and use of non-O blood-group donors (p=0.008). AR at 4 years and longer after LTx was associated with HLA mismatch at the B locus (p=0.01). CONCLUSIONS: Only a few recipient and operative factors were identified for AR after LTx. Moderately sensitized recipients identified by class II PRA exceeding 10% and those with HLA mismatches at the B and DR loci appear to be more susceptible to AR; however, such immunologic variations appear to be well controlled with current donor selection and immunosuppression protocols. The impact of donor-specific variables on AR is surprisingly strong and warrants closer inspection.

Lack of killer immunoglobulin-like receptor 2DS2 (KIR2DS2) and KIR2DL2 is associated with poor responses to therapy of recurrent hepatitis C virus in liver transplant recipients.

Killer immunoglobulin-like receptors (KIRs) expressed on natural killer and natural killer T cells are involved in activation of these cells and can influence antiviral immunity in the liver. This study investigated the association between KIR genetic diversity and sustained virologic response (SVR) to Peginterferon and Ribavirin (Peg/RBV) therapy in liver transplant (LT) recipients with hepatitis C virus (HCV) recurrence. We tested KIR genotypes in 44 HCV-infected LT recipients treated with Peg/RBV for 48 weeks. Patients were categorized as having KIR genotypes A/A or B/x and analyzed for association with SVR. Fifteen of 44 (34%) patients had SVR. Only 2 of 18 (11%) who lacked KIR2DS2/KIR2DL2 achieved SVR compared to 13 of 26 (50%) who carried these two genes (odds ratio: 8.0, 95% confidence interval: 1.5-42.0, P = 0.008). The association between lack of KIR2DS2/KIR2DL2 and SVR remained significant after exclusion of 10 patients with non-genotype 1 HCV. No correlation was found with other activating or inhibitory KIR genes. Absence of KIR2DS2 and/or KIR2DL2 is associated with failure of Peg/RBV therapy in patients with recurrent HCV after LT. These findings support the role of natural killer and natural killer T cells in HCV clearance after LT and might be generalizable to treatment of HCV infection outside the setting of LT.

Vision improvement in retinal degeneration patients by implantation of retina together with retinal pigment epithelium.

PURPOSE: To demonstrate efficacy and safety of the implantation of neural retinal progenitor cell layers (sheets) with its retinal pigment epithelium (RPE) in retinitis pigmentosa (RP) and dry age-related macular degeneration (AMD) patients with 20/200 or worse vision in the surgery eye. DESIGN: Interventional nonrandomized clinical trial. METHODS: Ten patients (six RP, four AMD) received retinal implants in one eye and were followed in a phase II trial conducted in a clinical practice setting. Early Treatment Diabetic Retinopathy Study (EDTRS) was the primary outcome measure. All implant recipients and nine of 10 tissue donors were deoxyribonucleic acids typed. RESULTS: Seven patients (three RP, four AMD) showed improved EDTRS visual acuity (VA) scores. Three of these patients (one RP, two AMD) showed improvement in both eyes to the same extent. Vision in one RP patient remained the same, while vision in two RP patients decreased. One RP patient has maintained an improvement in vision from 20/800 to 20/200 ETDRS for more than five years; at the six-year examination, it was still maintained at 20/320 while the nonsurgery eye had deteriorated to hand motion vision. This patient also showed a 22.72% increase in light sensitivity at five years compared to microperimetry results at two years; the other patients showed no improved sensitivity. Although no match was found between donors and recipients, no rejection of the implanted tissue was observed clinically. CONCLUSIONS: Seven (70%) of 10 patients showed improved VA. This outcome provides clinical evidence of the safety and beneficial effect of retinal implants and corroborates results in animal models of retinal degeneration.

A modified model of hindlimb osteomyocutaneous flap for the study of tolerance to composite tissue allografts.

Composite tissue allotransplantation (CTA) is the new frontier in transplantation. More than 25 hand allograft transplants have been performed worldwide, and the feasibility has been well established. The classical experimental model of CTA involves rat orthotopic hindlimb transplantation, a time-consuming procedure associated with high mortality and morbidity. We describe a rat heterotopic osteomyocutaneous flap that serves as a nonfunctional CTA, allowing the study of tolerance induction to a highly antigenic vascularized allograft of bone, muscle, and skin while minimizing the morbidity and mortality of full hind limb transplantation. In the present studies, we explored whether establishing chimerism by nonmyeloablative conditioning would induce tolerance to CTA. When compared with the classic hind limb transplantation model, these results demonstrate that our heterotopic hind limb flap is less morbid and as an effective experimental model for the study of CTA tolerance.

Transplantation of the hand, face, and composite structures: evolution and current status.

This article reviews the world experience in the newly emerging field of composite tissue allotransplantation. These allografts contain multiple tissues that are usually musculoskeletal structures with a skin or epithelial surface, such as hand, facial structures, larynx, tongue, ear, knee/femur, abdominal wall, and penis. They represent a new transplantation field, with only a 10-year experience and just over 50 clinical cases. This review of the 10-year world experience found uniform technical success, immunologic biology, and immunosuppression regimens very similar to solid organ transplants, and success strongly correlated with adherence to guidelines for psychiatric screening, thorough preparation of patient and families, intense postoperative monitoring, and assurance of medication access. All failures reported have been caused by lapses in these parameters. This early experience shows a great potential for application of these new procedures to the most challenging reconstructive needs.

The immunology of composite tissue transplantation.

Composite tissue allotransplantation holds great potential for reconstructive surgery. That these procedures can be successful has been clearly demonstrated by the success of hand, face, and larynx transplants around the world. Although the immunology of composite tissue allotransplantation mirrors that of any allogeneic organ transplant, there are several unique aspects to these grafts. This article reviews the immunology of transplantation, histocompatibility testing for composite tissue allotransplantation, graft rejection, immunosuppression, and specific immunologic considerations of composite tissue allotransplantation.

Lymphadenectomy prior to rat hind limb allotransplantation prevents graft-versus-host disease in chimeric hosts.

In previous rat studies, the use of mixed allogeneic chimerism (MAC) to induce host tolerance to hind limb allografts has resulted in severe graft-versus-host disease (GVHD). The purpose of this study was to determine if immunocompetent cells in bone marrow (BM) and/or lymph nodes (LNs) of transplanted limbs were responsible for inducing GVHD in mixed chimeric hosts. [ACI-->Wistar Furth] chimeric rats received ACI hind limbs that were non-irradiated, irradiated (1050 cGy) or lymphadenectomized. Rejection, GVHD and donor chimerism was assessed. Chimeric hosts rejected none of their limbs. However, hosts of non-irradiated hind limbs succumbed to GVHD 22.4+/-0.8 days after transplantation. In contrast, chimeras that received irradiated or lymphadenectomized ACI hind limbs showed no clinical or histological signs of GVHD at 5 months. We conclude that mixed chimeric hosts are susceptible to GVHD due to the immunocompetent cell load provided by the LNs, not the BM, of hind limb allografts.

Vision change after sheet transplant of fetal retina with retinal pigment epithelium to a patient with retinitis pigmentosa.

OBJECTIVE: To report the subjective and objective improvement in vision in a patient with autosomal dominant retinitis pigmentosa after transplantation of a sheet of fetal neural retina together with its retinal pigment epithelium. DESIGN: A sheet of fetal neural retina with its retinal pigment epithelium was transplanted into the subretinal space under the fovea unilaterally in a patient with retinitis pigmentosa with visual acuity of 20/800 in the treated eye. Early Treatment Diabetic Retinopathy Study visual acuity testing, scanning laser ophthalmoscope, tissue typing of the donor and recipient, fluorescein angiography, multifocal electroretinogram, multifocal visually evoked potential, and clinical examination were used. RESULTS: No clinical evidence of rejection was observed. There was no retinal edema or scarring. The transplant sheet lost its pigmentation by 6 months. MAIN OUTCOME MEASURES: A change in visual acuity from 20/800 to 20/400 (7 months), 20/250 (9 months), and 20/160 (1 year) was observed by Early Treatment Diabetic Retinopathy Study visual acuity testing. Independently, scanning laser ophthalmoscope testing at a different institution at 9 months showed a visual acuity of 20/270 at a 40 degrees field of view. CONCLUSION: This study indicates that fetal retina transplanted with its retinal pigment epithelium can survive 1 year without apparent clinical evidence of rejection and show continued improvement in Early Treatment Diabetic Retinopathy Study visual acuity.

Low-dose immunosuppression in a rat hind-limb transplantation model.

Composite tissue allografts (CTAs) offer an alternative to conventional reconstructive methods. However, the toxicity of the drugs that are required to prevent rejection has prevented its widespread clinical application. The purpose of this study was to determine whether a low-dose, corticosteroid-free combination regimen of tacrolimus and mycophenolate mofetil (MMF) would prevent rejection in a rat hind-limb model, with minimal toxic side effects. Three groups were used in this study. In group I, Wistar Furth (WF) rats received a syngeneic WF hind-limb. In groups II and III, WF rats received an ACI hind-limb. The latter were treated with tacrolimus-MMF. Assessment for rejection, flow cytometry, and mixed lymphocyte reactions was performed. Biopsies were taken regularly and at the time of killing. Combination therapy with low-dose tacrolimus-MMF effectively prolonged CTA survival indefinitely, with minimal side effects. Toxicity associated with immunosuppressive drugs can be avoided in a low-dose combination corticosteroid-free regimen.

Composite tissue allotransplantation in chimeric hosts: part I. Prevention of graft-versus-host disease.

BACKGROUND: Mixed allogeneic chimerism (MAC) has been shown to induce tolerance to composite tissue allografts (CTA). However, transplantation of unmanipulated donor-specific limbs results in severe graft-versus-host disease (GVHD). This suggests that nontolerant mature donor-derived cells in the CTA may affect the stability of chimerism, potentially resulting in GVHD. The aim of this study was to develop an approach to study and prevent GVHD in a mixed chimeric-rat hind-limb transplantation model. METHODS: [ACI-->WF] chimeras received a limb from Wistar Furth (WF) (syngeneic), Fisher (third-party), or ACI (irradiated [1,050 cGy] or nonirradiated) rats. In vitro tolerance was assessed using mixed lymphocyte reactivity (MLR) assays at the time the animals were killed. RESULTS: [ACI-->WF] chimeras with greater than 85% chimerism exhibited rejection-free survival of donor-specific hind limbs. However, 100% of these animals developed lethal GVHD 22.4+/-2.8 days after limb transplantation. [ACI-->WF] chimeras that underwent transplantation with irradiated ACI or syngeneic WF limbs showed no signs of rejection or GVHD at 5 months. Nonchimeric and third-party controls rejected limbs within 10 days. CONCLUSIONS: Conditioning of the host WF rats with 950 cGy of irradiation (sublethal, myeloablative) led to high levels of MAC without GVHD. The mature T-cell content of nonirradiated donor (ACI) limbs was sufficient to induce lethal GVHD in 100% of tolerant mixed chimeric [ACI-->WF] hosts. Irradiation of donor limbs before transplantation resulted in long-term donor-specific tolerance and prevented GVHD. These data demonstrate that (1) established chimeras could be susceptible to GVHD caused by immunocompetent donor cells transferred with the hind limb, and (2) inactivating these cells with irradiation prevents GVHD and destabilization of chimerism, and permits rejection-free graft acceptance.

Composite tissue allotransplantation in chimeric hosts part II. A clinically relevant protocol to induce tolerance in a rat model.

BACKGROUND: We and others have shown that mixed allogeneic chimerism induces donor-specific tolerance to composite tissue allografts across major histocompatibility complex barriers without the need for immunosuppression. However, a delay period between bone marrow transplantation and limb allotransplantation is required, making such protocols impractical for clinical application. This study eliminates this delay period in a rat hind limb allotransplantation model by performing mixed allogeneic chimerism induction and transplantation "simultaneously." METHODS: Group 1 included controls in which naïve Wistar Furth (WF) hosts received ACI hind limbs. Group 2 included (ACI-->WF) chimeras that received limbs from third-party donors (Fisher), and group 3 included chimeras that received irradiated (1,050 cGy) ACI limbs. In group 4, WF hosts conditioned with 950 cGy received irradiated (1,050 cGy) ACI limbs followed by infusion of 100 x 10(6) ACI T-cell-depleted bone marrow cells and immunotherapy (tacrolimus and mycophenolate mofetil) for 28 days. Group 5 animals received the same treatment as group 4 animals without immunotherapy. RESULTS: The rats in groups 1 and 2 rejected their limbs within 10 days. Only one rat in group 4 survived to the end of the study. Groups 3 and 5 demonstrated long-term limb survival without rejection or graft-versus-host disease. High levels of donor chimerism (>80%) were achieved and maintained throughout the study. Mixed lymphocyte reaction assays in both groups revealed donor-specific hyporesponsiveness with vigorous third-party reactivity. CONCLUSIONS: This study demonstrated that infusion of donor bone marrow cells into conditioned hosts immediately after limb transplantation results in stable mixed chimerism, robust tolerance, and reliable limb allograft survival.

Lack of donor hyporesponsiveness and donor chimerism after clinical transplantation of the hand.

BACKGROUND: Composite tissue allografts offer great potential in reconstructive surgery. However, the risks of immunosuppression and graft-versus-host disease (GVHD) after transplantation of vascularized bone in these grafts are significant. Transplantation of vascularized bone also may confer donor hematopoietic chimerism and, potentially, tolerance. We have followed two hand transplant recipients for more than 1 year to determine the level of chimerism and possible donor-specific tolerance, in addition to possible GVHD. METHODS: We performed kinetic studies on peripheral blood of two subjects after hand transplantation that included portions of the radius and ulna. We evaluated donor-specific reactivity, chimerism, and antibody production. RESULTS: Donor-specific tolerance did not develop clinically or in mixed lymphocyte reaction. The first subject recovered an excellent in vitro response to phytohemagglutinin, donor and third-party alloantigen, and by month 4 and at month 12 also recovered the ability to respond to Epstein-Barr virus. The second subject also demonstrated good in vitro proliferative responses, which were attenuated by immunosuppression. No phenotypic changes in mature hematopoietic lineages were detected by four-color flow cytometry other than those expected in response to immunosuppression. Donor chimerism was not detectable using four-color flow cytometry. Microchimerism (approximately 1:75,000 cells) was observed at the level of detection in some of the early posttransplantation specimens and was undetectable thereafter. CONCLUSIONS: In this particular transplantation and immunosuppressive regimen, the composite tissue allograft with vascularized bone marrow did not provide the immunologic benefit of tolerance induction nor cause GVHD.

Transplantation of intact sheets of fetal neural retina with its retinal pigment epithelium in retinitis pigmentosa patients.

PURPOSE: To show the safety of transplanting sheets of fetal neural retina together with its retinal pigment epithelium (RPE) to patients with retinitis pigmentosa. DESIGN: Interventional case series. METHODS: Sheets of fetal neural retina and RPE were transplanted together into the subretinal space near the fovea unilaterally in the eyes of five patients with retinitis pigmentosa who had only light perception in both eyes. The patients were followed for 6 months. The main outcome measures were tissue typing of both donors and recipients, fluorescein angiography, multifocal electroretinogram (mfERG) testing, and clinical examination. No immunosuppressive medications were given. RESULTS: No evidence of rejection was observed. Up to 6 months there was no evidence of tissue disintegration, retinal edema, or scarring. There was no change in vision both by Snellen acuity and with mfERGs. Growth of the transplant was noted in two of five patients at 6 months vs. 2 weeks. All patients typed were HLA mismatched with donor tissue. CONCLUSIONS: This study indicates that fetal retina can be transplanted together with its RPE and survive for at least 6 months without evidence of rejection. However, no improvements in vision were observed, possibly due to the severe retinal degeneration of the patients.