Anti-CD25 treatment and FOXP3-positive regulatory T cells in heart transplantation.

The interleukin-2 receptor alpha chain (IL-2Ra, CD25) plays a major part in shaping the dynamics of T cell populations following immune activation, due to its role in T cell proliferation and survival. Strategies to blunt the effector responses in transplantation have been developed by devising pharmaceutical agents to block the IL-2 pathways. However, such strategies could adversely affect the CD25(+)FOXP3(+)T regulatory (T reg) populations which also rely on intereukin-2 signaling for survival. The present study shows that a cohort of heart allograft recipients treated with Daclizumab (a humanized anti-CD25 antibody) display FOXP3 expression patterns consistent with functional T regulatory cell populations. High levels of FOXP3 were observed to correlate with lower incidence of and recovery from acute rejection, as well as lower levels of anti-donor HLA antibody production. Therefore, T reg populations appear fully functional in patients treated with Daclizumab, even when 5 doses were administered. By comparison, patients treated with fewer doses or no Daclizumab had a higher incidence of acute rejection, antibody production and graft failure. Therefore, our data indicates that Daclizumab treatment does not interfere with the generation of regulatory T cells and has a beneficial effect on heart allograft survival.

Regulation of ILT3 gene expression by processing of precursor transcripts in human endothelial cells.

Immunoglobulin-like transcript (ILT)-3 is a transmembrane receptor, which belongs to the immunoglobulin superfamily. In previous studies, we showed that allospecific CD8+CD28- T suppressor cells (Ts) induce the expression of ILT3 in human endothelial cells (EC) rendering them tolerogenic. Using a polymerase chain reaction (PCR)-based approach, we now demonstrate by cell fractionation and sequencing studies that ILT3 precursor RNA is expressed and retained in nuclei of resting EC. Ts interaction with EC or exposure of EC to interleukin-10 (IL-10) and interferon alpha (IFN-alpha) triggers processing of ILT3 pre-mRNA. Western blot analysis showed that the expression of the mature ILT3 transcript is accompanied by production of ILT3 protein.

The organizational model of the interregional transplant agency Organizzazione Centro-Sud Trapianti.

In Italy, all donation and transplant activities were officially disciplined in 1999 by the law 91 of April 1, 1999. This law enacted a coordinator-based model of transplantation, instituted the National Center for Transplantation (Centro Nazionale Trapianti-CNT), and endorsed the existing interregional transplant agencies (ITA), such as the Nord Italia Transplant program (NITp), the Associazione InterRegionale Trapianti (AIRT), and the Organizzazione Centro-Sud Trapianti (OCST). Within its borders each ITA has adopted its own organizational model; there is no overt centralized control exerted by the CNT according to the law 91/1999. The aim of the current work is to report on the organizational model adopted by OCST, the ITA gathering the Italian regions of Abruzzo, Basilicata, Calabria, Campania, Latium, Molise, Sardinia, Sicily, and Umbria.

Transplantation activity in the Organizzazione Centro-Sud Trapianti: a retrospective study from 1999 to March 2004.

BACKGROUND: The Organizzazione Centro-Sud Trapianti (OCST) was set up in 1998 to coordinate the organ procurement and transplantation activity of 9 italian regions (Abruzzo, Basilicata, Calabria, Campania, Lazio, Molise, Sardinia, Sicily, and Umbria), each referring to a local Regional Transplant Center. The aim of the present study was to estimate organ donation and transplantation rates in the OCST from 1999 to March 2004. MATERIALS AND METHODS: A retrospective study of organ donors and transplantation activity in the OCST during the study period was performed, pointing out donor epidemiological data, such as age and sex ratio, causes of death, reasons for discarding, and transplantation rates. Donors reported to the OCST were divided into 6 groups: A (October 1998-December 1999), B (2000), C (2001), D (2002), E (2003), and F (January-March 2004). RESULTS: From 1999 to March 2004, 2272 potential donors were reported to the OCST. The nonharvested donors rate increased up to 52% (Group F), which was lower than the previous period (Group E, 64%), but higher than in 1999 (Group A, 43%). The major contributing factor was family opposition, which was 38% in 2002 and 41% in 2003. CONCLUSIONS: The introduction of the OCST into the field of organ transplantation has yielded an increase in organ donation and transplantation activity within the regions that set it up from 1999-2003. This trend is a consequence of the growth of reported donors from the intensive care unit, which grew 12.7% from 2002 to 2003. From the data analysis of the first months of 2004, we expect confirmation of this trend.

Organizzazione Centro-Sud Trapianti: outcome analysis 1999 to 2002.

BACKGROUND: The Organizzazione Centro-Sud Trapianti (OCST), which was created in 1998, is organized into eight regional areas, each referring to a local Regional Transplant Coordinating Center. Organs are primarily allocated to meet the demands of transplant centers in each regional area. Urgencies, pediatric grafts, and paybacks are managed by an Interregional Transplant Coordinating Center. The aim of the current work is to report on the impact of introduction of OCST on organ donation and transplant activity over the period from 1999 to 2002. MATERIALS AND METHODS: A retrospective analysis of donor and transplant data charts over the period from 1999 to 2002 focused on outcome analysis based on donor epidemiological data, cause of death, reasons for discards and grafts performed at OCST local transplant centers. RESULTS: From 1999 to 2002, we observed a remarkable increase in organ donation from 8.8 to 22.5 donors per million people. Donor epidemiology showed an increase in median age and stroke incidence rates and a decrease in trauma cases. The nonharvested donor rate rose steadily over the study period, plateauing at 58%, which was compensated for by a threefold increase in donation. Family oppositions ranged as high as 35.5% on average, despite public efforts to support donation. Transplant activity rose by 76%. CONCLUSIONS: The institution of OCST and the efforts from central and regional authorities have yielded a significant increase in organ donation and transplant activity rates over the period from 1999 to 2002. Major areas of concern are the high opposition rate and the decreasing quality of harvested grafts. Long-term analysis is underway to assess the impact of OCST on the quality of transplants performed in the catchment area.

Cyclosporine--lessons from the first 20 years.

The introduction of cyclosporine in clinical practice led to a dramatic increase in long-term graft survival. At the Transplantation Center of the University of Rome La Sapienza, the survival rate at 5, 10, and 20 years was 35%, 22%, and 20% in the precyclosporine era and 75%, 60%, and 45%, respectively, after the use of cyclosporine-based immunosuppressive therapy. However, because of the nephrotoxicity of this, drug efforts are being made to reduce or avoid the use of calcineurin inhibitors. We advocate tailoring of immunosuppression to a minimal level on the basis of immunologic tests that permit a quantitative and qualitative evaluation of regulatory and effector cells.

Tolerization of dendritic cells by T(S) cells: the crucial role of inhibitory receptors ILT3 and ILT4.

Immunoglobulin-like transcript 3 (ILT3) and ILT4 belong to a family of inhibitory receptors expressed by human monocytes and dendritic cells. We show here that CD8+CD28(-) alloantigen-specific T suppressor (TS) cells induce the up-regulation of ILT3 and ILT4 on monocytes and dendritic cells, rendering these antigen-presenting cells (APCs) tolerogenic. Tolerogenic APCs show reduced expression of costimulatory molecules and induce antigen-specific unresponsiveness in CD4+ T helper cells. Studies of human heart transplant recipients showed that rejection-free patients have circulating TS cells, which induce the up-regulation of ILT3 and ILT4 in donor APCs. These findings demonstrate an important mechanism of immune regulation.

CD8+CD28- T suppressor cells and the induction of antigen-specific, antigen-presenting cell-mediated suppression of Th reactivity.

Human CD8+CD28- suppressor T cells (Ts) are a subset of T cells generated in the course of in vitro and in vivo immunizations. Ts recognize MHC class I:peptide complexes and inhibit the reactivity of T helper cells (Th) with cognate antigen specificity. We have demonstrated for the first time that CD8+CD28- Ts represent a unique subset of regulatory cells that induces the differentiation of tolerogenic antigen-presenting cells, initiating a suppressive loop which results in the induction and spreading of Th unresponsiveness.

Distinct mRNA microarray profiles of tolerogenic dendritic cells.

Dendritic cells are crucial to the activation as well as suppression of the immune response. Previous reports have illustrated that APC interacting with antigen-specific T suppressor cells become tolerogenic, inducing T helper anergy. To characterize the molecular changes occurring in tolerogenic APC, the mRNA profile of KG-1 dendritic cells exposed to allospecific T helper and T suppressor cells were analyzed. This study now provides evidence that immature dendritic cells stimulated by T suppressor cells differentiate into mature dendritic cells with a distinct phenotype. The identification of Ts induced pathways of dendritic cell differentiation is critical to the development of new therapeutic strategies.

Human xenospecific T suppressor cells inhibit T helper cell proliferation to porcine aortic endothelial cells, and NF-kappaB activity in porcine APC.

Human T suppressor cells (Ts), capable of preventing autologous T helper cells (Th) from reacting against xenogeneic pig endothelial cells and pig APC can be generated in vitro. Ts derive from a population of CD3(+)CD8(+)CD28(-) T lymphocytes and specifically recognize the MHC class I antigens of the APC used for in vitro immunization. To study the mechanism that underlies suppression, we investigated whether Ts inhibit the expression of costimulatory molecules in xenogeneic professional and semiprofessional APC. We found that Ts down-regulate Th-induced expression of CD86 in pig APC, and that this effect occurs at the level of transcription, as indicated by nuclear run-on and Northern blot assays. EMSA results revealed that inhibition of CD86 expression is mediated by inactivation of transcription factor NF-kappaB. Furthermore, transfection of pig APC with a vector expressing NF-kappaB p65 partially rescued Th-induced expression of the CD86 molecule. These results strongly support the concept that xenospecific Ts inhibit the APC function of xenogeneic cells by preventing activation of NF-kappaB.

Pediatric renal transplantation: anesthesia and perioperative complications.

The appropriate choice of anesthesia for patients (pts) undergoing renal transplantation (Ktx) requires minimal toxicity and accurate monitoring for pts at high risk for metabolic, cardiovascular, and respiratory perioperative complications. We evaluated the anesthetic management and postoperative follow-up in pediatric Ktx performed in the last 12 years in our institution. From 1988 to 1999, 75 ASA class II-III pts (45 males, 22 females) younger than 18 years scheduled for Ktx were studied: 49 received a graft from a cadaveric donor (CD) and 26 from a living donor (LD). All pts were treated with dialysis within 24 h before the procedure. Standard monitoring consisted of an electrocardiogram, central venous pressure, non-invasive arterial pressure, pulse oximetry, and inspiratory and expiratory gas analysis. If necessary, an arterial cannula and pediatric pulmonary catheter were introduced. Anesthesia was induced with sodium thiopental, propofol, halothane, or sevoflurane and maintained with isoflurane and/or fentanyl and droperidol in O2:N2O (FiO2 0.4%). As muscle relaxants atracurium or cisatracurium besilate were used, except in allergic pts, in whom vecuronium or rocuronium bromide was administered. Dopamine, 20% mannitol, and furosemide were used to increase diuresis. Continuous morphine and ketoralac infusions were used for postoperative pain relief. The surgical technique was the same in all cases. Complications and renal-function (RF) recovery were evaluated relating to CD and LD using the chi-square test; differences in mean anesthesia and surgical time were evaluated by Student's t-test; survival curves were calculated from the day of Ktx to death or last follow-up and estimated by the Kaplan-Meier method. Values of P below 0.05 were considered significant. Postoperative immunosuppressive therapy was based on cyclosporine together with other conventional drugs. Mean anesthesia time was 228 +/- 65 min. Mean kidney ischemia time for CD was 16.5 +/- 4 h. Four pts (3 CD, 1 LD) died within 72 h postoperatively: 3 due to cardiac failure and 1 to metabolic coma. Six pts showed cardiovascular and 3 had infective complications, all successfully treated. Three pts (2 CD, 1 LD) died within 2 to 12 months after, surgery; 10 (6 CD, 4 LD) had graft failure and are still alive on dialysis; 58 (38 CD, 20 LD) are alive in good health after a mean follow-up of 57.6 +/- 36.6 months (range 12-120 months). Fifteen of 26 pts younger than 12 years (21 CD and 5 LD) recovered RF intraoperatively (10 CD, 5 LD); 1 with CD and 1 with LD showed postoperative graft failure and 2 with CD died within 72 h postoperatively, 22 (18 CD and 4 LD) are alive in good health. This group showed no statistical difference compared to pts older than 12 years. Of 16 pts (15 CD and 1 LD) with body weight (BW) less than 25 kg, 6 showed intraoperative (5 CD, 1 LD) recovery of RF. The 3 deaths were all in CD pts, 2 within 72 h and one 2 months after surgery; only 1 LD had postoperative graft failure. Twelve pts (75%) (12 CD, 80%) are alive in good health. Compared to pts with BW of 25 kg or more, this group showed lower intraoperative recovery of RF (P < or = 0.05). No peri- and postoperative complications occurred in all 26 LD pts (100%). Recent advances in surgery, anesthesia, immunosuppression, and antimicrobial prophylaxis have made Ktx a more predictable procedure even in pediatric pts. For high-risk pts, mortality and morbidity can be controlled by accurate surgical, anesthetic, and postoperative management. Pts younger than 12 years and with BW less than 25 kg are more likely to develop peri- and postoperative complications.