Donor specific anti-HLA antibodies in hematopoietic stem cell transplantation. Single Center prospective evaluation and desensitization strategies employed.

BACKGROUND: In the setting of mismatched-hematopoietic stem cells transplantation, the detection of antibodies directed against donor-specific HLA allele(s) or antigen(s) (DSA) represents a barrier for engraftment. It is thus necessary to plan an immunosuppressive strategy, or to select an alternative donor. This prospective study aimed at evaluating the efficacy of our strategy for testing DSAs and the efficacy of the desensitization strategy (DS) employed between November 2017 and November 2020. MATERIALS AND METHODS: The anti-HLA antibody search was performed using the Luminex bead assays (Lifecode ID and LSA I/II-Immucor) and expressed as mean fluorescence intensity (MFI >1,000 positive). If the patient had DSAs and no alternative donors, a DS was employed with rituximab (day -15), 2 single volume plasmaphereses (PP; days -9 and -8), intravenous immunoglobulins (day -7) and infusion of HLA selected platelets, if persistent DSAs were directed against class I HLA. DS was scheduled with or without PP, according to the DSA MFI (>1,000 or <5,000) and FCXM (flow cytometry crossmatch). RESULTS: Twenty-two out of 126 patients (17.46%) showed anti-HLA antibodies, 5 of them DSAs (3.97% of total); 3 patients underwent DS obtaining engraftment. Female gender (p=0.033) and a history of previous pregnancies or miscarriages (p=0.009) showed a statistically significant impact on alloimmunization. Factors associated with a delayed neutrophil engraftment were patient's female gender (p=0.039), stem cell source (p=0.025), and a high HSCT-specific comorbidity index (p=0.028). None of the analyzed variables, including the DSA detection, influenced engraftment. CONCLUSIONS: Our study confirms the importance to test DSAs in mismatched-hematopoietic stem cells transplantation The DS used proved successful in removing DSAs. Prospective multicenter studies are needed to better define and validate consensus strategies on DSA management in HSCT.

[Multimodal treatment for acute antibody-mediated renal transplant rejection: successful rescue therapy with combined plasmapheresis, photopheresis and intravenous immunoglobulin]. / Trattamento multimodale per il rigetto acuto anticorpo-mediato nel trapianto di rene: terapia di salvataggio con plasmaferesi, fotoaferesi e immunoglobuline endovenose.

The fundamental role of antibodies in the development of acute graft rejection has been established recently. Antibody-mediated acute rejection may develop at any time during the post-transplant period. Several therapeutic approaches have been proposed in the last decades. However, there is no standardized therapy. The aim of this study is to report the Sapienza University experience of combined plasma treatment and high-dose intravenous immunoglobulin ± extracorporeal photopheresis. From January 2006 to September 2009, 6 patients were treated at Sapienza University. In 5 cases (83%) complete regression of the acute rejection was observed, followed by stable renal function (median creatinine value at 1-year follow-up: 1.5 mg/dL). No adverse events were reported. Our approach seems to give good results in terms of graft survival and procedure safety. Further studies on a larger number of patients will be needed to confirm the validity of these findings. Moreover, comparison between our protocol and other treatments is necessary.

[Adacolumn apheresis for hepatitis C virus in patients waiting for kidney transplant. Preliminary study]. / Trattamento con Adacolumn leucocitaferesi per la rimozione del virus C nei pazienti in lista per trapianto di rene. Studio preliminare.

Hepatitis C virus (HCV) infection occurs much more frequently in the hemodialysis population than in the general population. Patients with chronic kidney disease with persistent HCV infection may develop serious and progressive chronic liver disease, with associated long-term morbidity and mortality related to cirrhosis and hepatocellular carcinoma. Monocytes and macrophages are known to produce extrahepatic breeding sites and spread the disease. Our aim was to lower the levels of macrophages, granulocytes, monocytes, proinflammatory cells and viremia using an extracorporeal device: the Adacolumn ® leukocyte apheresis system (Otsuka). The Adacolumn is a direct hemoperfusion-type leukapheresis device. The column is a single-use (disposable) polycarbonate column with a capacity of about 335 mL, filled with 220-g cellulose acetate beads of 2 mm in diameter bathed in physiological saline. The carriers adsorb ''activated'' granulocytes and monocytes/macrophages that bear Fc and complement receptors. The patients underwent five 1-hour sessions for five consecutive days. The column was placed in an extracorporeal setting with a perfusion rate of 30 mL/min and a duration of 60 minutes. A reduction of viremia was observed in all patients in association with a decrease in cytokine levels and a proportional decrease in immune cells. Although this study investigated responses in a small number of patients, it was shown that the Adacolumn changed the cellular immunity and promoted early viral response.

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.

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.

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 (< 6 months) 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.

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.