P. Cinti

Detection of T suppressor cells in patients with organ allografts.

Specific immunosuppression of hosts immune response to donor HLA antigens has been a major goal to clinical transplantation. Recent evidence has been accumulating to show that a distinct population of T cells expressing the CD8(+) CD28(-) phenotype display suppressor function and inhibit Th activation and proliferation by modulating the APC function. To assess the presence of Ts in transplant recipients circulation, we have developed a flow cytometry method that measures the expression of costimulatory molecules on donor APC exposed to recipient Th and Ts. Our results demonstrate that quantitation of the capacity of CD8(+) CD28(-) T cells from patient circulation to suppress the activation of costimulatory molecules (CD80, CD86) on donor APC offers a reliable tool for monitoring specific immunosuppression against the graft in solid organ transplantation.

Evaluation of pretransplant immunologic status in kidney-transplant recipients by panel reactive antibody and soluble CD30 determinations.

Objectives. To retrospectively compare the accuracy of pretransplant panel of reactivity antibodies (PRA) and serum level of soluble CD30 (sCD30) in predicting early (<6 months) acute rejection (AR) in living-donor and deceased-donor kidney-transplant (KT) patients. Methods. Pretransplant sera of 24 KT recipients were retrospectively tested for sCD30 and compared with PRA. Inclusion criteria were de novo graft patients on calcineurin–inhibitor-based immunosuppression, minimum follow-up of 1 year, alive with a functioning graft, and stable renal function over the last 12 months. Objective measures were incidence of biopsy-proven AR (BPAR) within 6 months of KT and sCD30 and PRA diagnostic indexes. The relative risk (RR) of BPAR for each test was also obtained. Results. Fourteen (58.3%) patients presented at least one episode of BPAR within 6 months of KT. All rejection episodes were responsive to steroid treatment. PRA was positive in six (25%) patients, and four (66.7%) of them presented at least one episode of BPAR. sCD30 tested positive in nine (37.5%) patients, and all these later presented at least one episode of BPAR. sCD30 and PRA diagnostic indexes in predicting early (< 6months) BPAR were sensitivity 64.2% versus 28.5%; specificity 100% versus 80%; accuracy 79.1% versus 50%; positive predictive value 100% versus 66.6%; and negative predictive value 66.6% versus 44.4%. The RR of early AR was 1.4 in PRA-positive patients and extremely higher in the sCD30-positive group. Conclusions. Pretransplant sCD30 is a more accurate predictor of AR when compared with PRA. These results support its use in the pretransplant work-up of kidney-graft recipients.

Soluble Ig-Like Transcript 3 Inhibits Tumor Allograft Rejection in Humanized SCID Mice and T Cell Responses in Cancer Patients

Attempts to enhance patients’ immune responses to malignancies have been largely unsuccessful. We now describe an immune-escape mechanism mediated by the inhibitory receptor Ig-like transcript 3 (ILT3) that may be responsible for such failures. Using a humanized SCID mouse model, we demonstrate that soluble and membrane ILT3 induce CD8+ T suppressor cells and prevent rejection of allogeneic tumor transplants. Furthermore, we found that patients with melanoma, and carcinomas of the colon, rectum, and pancreas produce the soluble ILT3 protein, which induces the differentiation of CD8+ T suppressor cells and impairs T cell responses in MLC. These responses are restored by anti-ILT3 mAb or by depletion of soluble ILT3 from the serum. Immunohistochemical staining of biopsies from the tumors and metastatic lymph nodes suggests that CD68+ tumor-associated macrophages represent the major source of soluble ILT3. Alternative splicing, resulting in the loss of the ILT3 transmembrane domain, may contribute to the release of ILT3 in the circulation. These data suggest that ILT3 depletion or blockade is crucial to the success of immunotherapy in cancer. In contrast, the inhibitory activity of soluble ILT3 on T cell alloreactivity in vitro and in vivo suggests the potential usefulness of rILT3 for immunosuppressive treatment of allograft recipients or patients with autoimmune diseases.

MECHANISM OF LIVER ALLOGRAFT REJECTION : THE INDIRECT RECOGNITION PATHWAY

Transplant rejection is mediated by the direct and indirect pathways. To explore the role of the indirect recognition pathway in the rejection of liver allografts, T cells obtained from peripheral blood were expanded in medium containing IL-2 and tested in LDA for reactivity to synthetic peptides corresponding to the hypervariable regions of the mismatched HLA-DR antigen(s) of the donor. Serial investigations of 17 recipients showed that T-cell reactivity to donor HLA-DR peptides was strongly associated with acute rejection episodes. In recipients carrying a graft that was mismatched by two HLA-DR alleles, a single donor antigen was targeted during primary rejection, although allopeptide reactivity against the second HLA-DR antigen was observed during subsequent episodes of acute rejection. The finding that allopeptide reactivity occurs early following transplantation and is predictive of rejection is consistent with the notion that processing of donor alloantigens by recipient APCs activates the indirect T-cell recognition pathway that plays a major role in initiating and amplifying allograft rejection.

Tailoring of immunosuppression in renal and liver allograft recipients displaying donor specific T-suppressor cells.

Although transplantation tolerance cannot be yet reliably achieved in humans, there is evidence that active immunosuppression contributes to the maintenance of quiescence. However, the mechanism that underlies quiescence and the precise identity of regulatory cells are not completely understood. We have demonstrated that allograft recipients who remain rejection-free display allospecific T-suppressor cells (Ts). Ts express the CD8(+) CD28(-) phenotype, recognize major histocompatibility complex (MHC) class I antigens, and suppress the up-regulation of costimulatory molecules induced by CD40 ligation of donor antigen presenting cells. The presence of Ts is inversely correlated with T cell alloreactivity to donor MHC peptides, alloantibody production, and rejection. Monitoring of Ts has been successfully used in our studies for tailoring immunosuppression in kidney and liver allograft recipients.

Immunoadsorption with protein A in humoral rejection of kidney transplants

The presence of alloantibodies may play a role in accelerated or acute humoral rejection. Different therapeutic strategies based on a removal of anti donor antibodies and prevention of their resynthesis have been used in the management of transplant rejection episodes. Immunoadsorption with staphylococcal protein A, a method to selectively remove immunoglobulin G, may represent a new treatment to reverse humoral rejection in kidney transplantation. From 1991 to January 1996, such a method was used in 23 patients in whom an acute humoral rejection developed over a mean period of 14.1 +/- 9.5 days after operation. Twenty-two patients had been transplanted from living donors and one from a cadaveric donor. The ages ranged from 23 to 58 years (mean, 34 +/- 10 years). All transplants were performed according to a negative direct crossmatch. Basic immunosuppression included cyclosporine, steroids, azathioprine, and antilymphocyte globulin or monoclonal antibodies (OKT3). Rejection was diagnosed on the basis of hematochemical tests, Doppler ultrasonography, and kidney biopsy. Only steroid and monoclonal and polyclonal antibody resistant rejections with > 165% positive direct crossmatches against the donor were treated with Protein A immunoabsorption. The procedure used is based on the treatment of 2-3 plasma volumes for the first 2 days and then every other day until a negative crossmatch is obtained, together with improvement in clinical status (mean treatments, 7.3 +/- 4.5 [range, 4-23]; mean duration of treatment, 12.3 +/- 10.2 days [range, 3-44]). From the start of treatment, azathioprine is replaced by cyclophosphamide at a dose of 1-2 mg/kg/day. During treatment, a remarkable fall in immunoglobulin G levels is achieved on the first day, whereas immunoglobulin M titers remain constant, with a slight decrease in serum albumin. Immediately after treatment, a negative crossmatch was found in 22 (95.6%) of 23 patients. In six patients (26%), graft function did not recover, and one patient (4.3%) died. Preliminary results show that immunoabsorption with staphylococcal protein A may be an effective support in the treatment of humoral acute rejection, particularly when it is performed as soon as an early diagnosis of humoral rejection is made. In fact, such treatment has a highly selective adsorption, allows treatment of large volumes of plasma, and can achieve a rapid decrease in the titer of circulating immunoglobulins.

Enhanced production of interferon-γ by T lymphocytes cloned from rejected kidney grafts

Seventy-seven T cell clones were generated from cell blasts infiltrating rejected kidney allografts. All clones, either CD4 or CD8, displayed cytolytic activity evaluated by lectin-dependent cell-mediated cytotoxicity (LDCC) and natural killer activities. Furthermore, both types of clones were able to produce IFN-gamma following PHA stimulation. These data suggest that the graft infiltrate is characterized by T cell clones with cytolytic potential responsible for the killing of graft cells. The production of IFN-gamma, enhancing the class II MHC expression, may amplify the recipient immune response.

Cytokine Level Modifications: Molecular Adsorbent Recirculating System Versus Standard Medical Therapy

INTRODUCTION Acute-on-chronic liver failure (ACLF) is a systemic inflammatory reaction, which is characterized by a predominantly proinflammatory cytokine profile, causing the transition from stable cirrhosis to ACLF. The aim of the present study was to evaluate the changes in several cytokines associated with inflammatory liver disease and liver regeneration among 15 ACLF patients treated with the Molecular Adsorbent Recirculating System (MARS) compared with 15 patients treated with standard medical therapy (SMT). The subjects showed various disease etiologies but similar values for Model End-stage Liver Disease scores. METHODS In the MARS group, 15 (10 male and 5 female) patients were treated with MARS (Gambro). The number of MARS applications was nine; the length of applications was 8 hours. In the SMT group; 15 (10 male and 5 female) patients were treated with SMT. The patients were monitored for 30 days from inclusion with a survival follow-up at 3 months. Statistical results were calculated with SPSS14.0 (SPSS Inc, Chicago, Ill). A P < .07 was considered significant. RESULTS In the MARS group, we observed significant changes in the levels of Interleukin (IL)-6, IL-1, IL-10, and tumor necrosis factor (TNF)-alpha in association with improved hepatocyte growth factor. Patient survival at 3 months was 60%. The SMT group showed only a significant change in TNF-alpha (P = .03). Patient survival at 3 months was 30%. CONCLUSION The MARS liver support device corrected pathophysiologies of ALF and may be used to enhance spontaneous recovery or as a bridge to transplantation.

Minimization of immunosuppressive therapy and immunological monitoring of kidney transplant recipients with long-term allograft survival

Incidence of cardiovascular complications, cancers and chronic allograft nephropathy (CAN) suggests reduction of immunosuppressive dosages. Some studies analyzed the effects of minimization of immunosuppression until the avoidance of immunosuppressive drugs. However minimization seems to be related to a higher incidence of acute rejection. Induction of tolerance after transplantation and use of immunological tests that could monitor the immune reactivity are required. The aim of this study is to evaluate immunological state in a group of recipients after deceased and living donor kidney transplantation and to minimize immunosuppressive therapy monitoring simultaneously clinical and immunological parameters. We analyzed 41 patients, 38 from deceased donors and 3 from living donor kidney transplantation. All patients were treated with triple immunosuppressive therapy: cyclosporine or sirolimus or tacrolimus, mycophenolate mofetil and steroids. In all recipients the presence of CD8+CD28- T suppressor cells (Ts) was analyzed. Patients were divided in 2 groups, according to the presence of Ts. In patients with Ts, (Group A, n=19), mycophenolate mofetil (MMF) was progressively reduced and then stopped. Steroids were subsequently reduced and then interrupted, maintaining an immunosuppressive therapy with low doses of calcineurin inhibitors (CNI) or sirolimus (SIR). 22 patients were without presence of Ts: we enrolled for the study only patient acute rejection free, without proteinuria and with creatinine levels stable (Group B, n=19). In these patients, MMF was reduced and then stopped, while steroids were decreased to 5 mg at alternate days, maintaining CNI or SIR at medium therapeutic dosages (minimized therapy). Patient and graft overall survival in Group A and in Group B were respectively at 100% and 94.7%. Incidence of acute rejection was respectively at 0% in group A and 15.7% in Group B. Presence of episodes of acute rejection in Group B confirms risk of later minimization of steroids and the relevance of the analysis of recipient immunological reactivity before modification of immunosuppressive therapy. A careful evaluation of recipient immune reactivity with the presence of T regulatory cells can allow adequate and personalized immunosuppressive regimens, without high risks of acute rejection.

Multimodal therapy with combined plasmapheresis, photoapheresis, and intravenous immunoglobulin for acute antibody-mediated renal transplant rejection: A 2-year follow-up

BACKGROUND Recently, the role of antibodies has been documented in the development of acute rejection episodes. Antibody-mediated acute rejection (AMAR) may develop at any time after transplantation, with an incidence of almost 7%. Several therapeutic approaches have been proposed in the past decades. However, no data exist regarding combined plasma treatment (PT) and extracorporeal photopheresis (ECP). The aim of this study was to report an initial single-center experience of combined PT and ECP with high-dose intravenous immunoglobulin (IVIg) for the treatment of AMAR. METHODS Three patients were treated with this approach. RESULTS In 2 cases, we observed immediate restoration of graft function, and in 1 case, in which we interrupted the protocol owing to lack of patient consent, the graft was lost. No organ infections were reported during the therapy period. The rationale for use of ECP is related to the presence of mixed antibody and cell-mediated mechanisms in acute rejection episodes. ECP inhibits specific pathogenic T cells. CONCLUSION Our approach seemed to give good results in terms of graft survival and safety.