Photopheresis for the prevention of rejection in cardiac transplantation. Photopheresis Transplantation Study Group

Apoptotic cell-based therapies against transplant rejection: role of recipient's dendritic cells

One of the ultimate goals in transplantation is to develop novel therapeutic methods for induction of donor-specific tolerance to reduce the side effects caused by the generalized immunosuppression associated to the currently used pharmacologic regimens. Interaction or phagocytosis of cells in early apoptosis exerts potent anti-inflammatory and immunosuppressive effects on antigen (Ag)-presenting cells (APC) like dendritic cells (DC) and macrophages. This observation led to the idea that apoptotic cell-based therapies could be employed to deliver donor-Ag in combination with regulatory signals to recipient’s APC as therapeutic approach to restrain the anti-donor response. This review describes the multiple mechanisms by which apoptotic cells down-modulate the immuno-stimulatory and pro-inflammatory functions of DC and macrophages, and the role of the interaction between apoptotic cells and APC in self-tolerance and in apoptotic cell-based therapies to prevent/treat allograft rejection and graft-versus-host disease in murine experimental systems and in humans. It also explores the role that in vivo-generated apoptotic cells could have in the beneficial effects of extracorporeal photopheresis, donor-specific transfusion, and tolerogenic DC-based therapies in transplantation.

Investigation of heparin-related hypotensive adverse events during photopheresis: utility of a patient care database

BACKGROUND

Extracorporeal photopheresis (ECP) is a procedure in which leukocytes are harvested from a patient's whole blood, treated with a DNA binding dye and ultraviolet light to inactivate lymphocytes, and then returned into the patient's circulation. In January 2008, we observed moderately severe anaphylactoid reactions in eight of 16 patients undergoing ECP.

CASE STUDY

Each affected individual exhibited hypotension of sudden onset, usually with tachycardia, during the return of heparin-anticoagulated blood at the end of the first cycle of collection of leukocytes. A systematic investigation of possible contributing factors revealed that all reactions were associated with administration of a single new lot of heparin.

RESULTS

Changing to a different manufacturer of heparin eliminated the occurrence of further such hypotensive reactions during ECP. Although the symptoms were initially attributed to vasovagal reactions or dehydration, their temporal association with exposure to a new lot of heparin suggested a procedure-related phenomenon. Of particular note, was the finding that of the eight patients who had reactions at any time, six had initial exposures without reactions, suggesting a process of sensitization.

CONCLUSION

This study demonstrated the value of a patient database listing lot numbers of all medications and components used in each routine ECP procedure for facilitating rapid determination of common patient exposures, making it easier to determine the cause of adverse events, in this case, a particular lot of heparin responsible for the hypotensive adverse events.

Guidelines on the use of therapeutic apheresis in clinical practice--evidence-based approach from the Apheresis Applications Committee of the American Society for Apheresis

The American Society for Apheresis (ASFA) Apheresis Applications Committee is charged with a review and categorization of indications for therapeutic apheresis. Beginning with the 2007 ASFA Special Issue (fourth edition), the subcommittee has incorporated systematic review and evidence-based approach in the grading and categorization of indications. This Fifth ASFA Special Issue has further improved the process of using evidence-based medicine in the recommendations by refining the category definitions and by adding a grade of recommendation based on widely accepted GRADE system. The concept of a fact sheet was introduced in the Fourth edition and is only slightly modified in this current edition. The fact sheet succinctly summarizes the evidence for the use of therapeutic apheresis. The article consists of 59 fact sheets devoted to each disease entity currently categorized by the ASFA as category I through III. Category IV indications are also listed.

[Rationale for the use of extracorporeal photochemotherapy in children]

The management of immune diseases in children remains challenging, although significant advances have been made. In addition to pharmacological approaches, extracorporeal photochemotherapy (ECP) is distinctive in its ability to provide immunomodulation without immune suppression or toxicity. However, in practice, this therapy is not widely used because of logistical issues and the lack of robust clinical pediatric studies. Here, we discuss the potential clinical applications of ECP in children and emphasize the need for a rigorous and specifically pediatric clinical evaluation of ECP.

The use of fluid boluses to safely perform extracorporeal photopheresis (ECP) in low-weight children: a novel procedure

Apheresis procedures in small children are technically challenging and require special planning with attention to extracorporeal volume. Discontinuous procedures such as extracorporeal photopheresis (ECP) require additional consideration. Alternative methods to perform ECP have been utilized in small children that require manipulation of mononuclear cells outside the standard closed-loop system. We present a safe and feasible alternative to the procedure for children who weigh less than 40 Kg, while maintaining a closed loop, sterile system utilizing the UVAR XTS device. A retrospective chart review was performed analyzing the use of fluid boluses (normal saline in those between 20 and 40 Kg, 5% albumin in those under 20 Kg) before ECP. Eleven patients underwent 334 ECP procedures for acute and chronic graft-versus-host disease (n = 9), and for prevention of graft-versus-host disease (n = 2). Volumes of fluid boluses were calculated based on the expected extracorporeal volume during the first draw cycle. Treatments consisted of at least three draw cycles using the 125 mL bowl. The median weight was 28.5 Kg (range 19 to 39); nine of 11 required red cell transfusions to maintain adequate hematocrit. Complications attributed to ECP included tachycardia, dizziness, nausea, and hypotension; these occurred either in combination or isolation in 31% of the procedures and resolved following additional fluid boluses. Only three (0.8%) required early photoactivation due to these complications. The median time to completion of treatment was 2 h and 58 min (range 1:30 to 5:03). ECP is well tolerated in low-weight pediatric patients if hematocrit and hydration are carefully maintained.

[Extracorporeal photochemotherapy or immunotherapy using cells modified by photochemistry]

Extracorporeal photochemotherapy (ECP) is an autologous cell therapy used for the treatment of diseases involving pathogenic cells: cutaneous T-cell lymphoma, organ rejection and graft versus host disease. During an ECP procedure, patients receive a cellular product consisting of autologous mononuclear cells, containing the pathogenic cells, treated with a photosensitising agent and an UV-A radiation. The aim of the treatment is to induce a specific immune reaction modulating the activity of untreated pathogenic lymphocytes responsible for the disease and therefore an improvement of clinical manifestations. The precise mechanisms of action remain to be defined in humans. Its efficacy coupled with the absence of side effects could lead to decrease the use of immunosuppressive drugs. PCE appears as an immunotherapy using cells modified by photochemistry, which allows specific immune modulation of pathogenic lymphocytes.

Extracorporeal photopheresis in a rat model of pulmonary fibrosis

Extracorporeal photopheresis has anti-inflammatory properties. The development of pulmonary fibrosis includes inflammatory episodes. This study evaluates effects of extracorporeal photopheresis in experimental pulmonary fibrosis. The bleomycin model of pulmonary fibrosis was used. Two groups of 4 rats received intratracheal bleomycin to induce fibrosis. The treatment group received infusions of photochemically treated leukocytes harvested from syngeneic animals. All animals were sacrificed at day 21 after fibrosis induction and analyzed with respect to lung histology and hydroxyproline content, cellular composition of bronchoalveolar lavages, serum and lavage concentrations of transforming growth factor-beta, interferon-gamma, and interleukin-10, and expression of selected genes in the lung. Interleukin-10 and transforming growth factor-beta protein concentrations increased in the plasma of treated animals, whereas the interferon-gamma protein concentration was higher in bronchoalveolar lavages. Interferon-gamma gene expression was up-regulated in the lung tissue of treated animals. No significant differences between treated and untreated animals were found with respect to hydroxyproline, histology, and lavage cell count. To conclude, extracorporeal photopheresis has positive molecular effects but does not attenuate experimental lung fibrosis with respect to histology, hydroxyproline, and lavage cell count in the applied treatment regimen. Further investigations of extracorporeal photopheresis in experimental pulmonary fibrosis are justified.

Photopheresis therapy for problematic renal allograft rejection

BACKGROUND

Photopheresis is an immunomodulatory therapy for the treatment of T cell-mediated disorders. It has been used for rejection prophylaxis in cardiac transplantation, adjuvant treatment of bronchiolitis obliterans in lung transplantation, treatment of graft verse host disease, and in a small number of cases, for treatment of acute rejection in renal transplantation. Little is known of long-term outcomes following the use of photopheresis in solid organ transplantation.

METHODS

We report prospective follow-up of our consecutive experience of the use of photopheresis as adjuvant/salvage therapy for problematic rejection in patients undergoing renal transplantation. Transplant graft survival, infective and malignant outcomes were reported.

RESULTS

A cohort of 10 renal transplants recipients received photopheresis therapy for therapy-resistant rejection. Conventional therapy included an average of 6.2 g pulse methyl-prednisolone and 17.1 days antilymphocyte therapy. The cohort received additional photopheresis therapy when the unresponsive nature of their rejections raised concerns of graft loss. Median follow-up censored for patient loss was 66.7 months following photopheresis commencement. Rejection resolved in association with photopheresis use in all 10 patients. Six patients continued to have stable graft function (median serum creatinine: 191.5 micromol/L) at a median follow-up of 71.0 months. There has been one patient death from sepsis and two from malignancy with functioning grafts while one graft has been lost to disease recurrence.

CONCLUSION

Photopheresis may have a role as an adjuvant or salvage antirejection therapy in solid organ transplantation. Furthermore, evaluation in randomized controlled clinical trials is required to evaluate its potential.

Extracorporeal photo-apheresis for the treatment of steroid-resistant graft versus host disease

Acute and chronic graft versus host disease are frequent and potentially severe complications of allogeneic hematopoietic stem cell transplantation and are among the leading causes of non-relapse transplant-related mortality. For patients with steroid refractory disease, prognosis is particularly poor and although a variety of treatment options are available, responses are commonly transient and the side effects often intolerable. Since it was first introduced for the treatment of cutaneous T-cell lymphoma, extracorporeal photo-apheresis has been utilized as an immunomodulatory therapy for certain autoimmune diseases and solid organ transplant rejection. Recently, extracorporeal photo-apheresis has become a promising alternative for patients with graft versus host disease with disabling or potentially lethal complications. Here we review the experience of extracorporeal photo-apheresis for the treatment of steroid refractory acute and chronic graft versus host disease based on the current literature.

Graft-versus-host disease

Haemopoietic-cell transplantation (HCT) is an intensive therapy used to treat high-risk haematological malignant disorders and other life-threatening haematological and genetic diseases. The main complication of HCT is graft-versus-host disease (GVHD), an immunological disorder that affects many organ systems, including the gastrointestinal tract, liver, skin, and lungs. The number of patients with this complication continues to grow, and many return home from transplant centres after HCT requiring continued treatment with immunosuppressive drugs that increases their risks for serious infections and other complications. In this Seminar, we review our understanding of the risk factors and causes of GHVD, the cellular and cytokine networks implicated in its pathophysiology, and current strategies to prevent and treat the disease. We also summarise supportive-care measures that are essential for management of this medically fragile population.

[Extracorporeal photopheresis]

Photopheresis, originally developed in dermatology, has become a treatment method accepted across various disciplines. A basic knowledge of photomedicine and photobiology is one of the cornerstones of dermatology. Even if photopheresis is used for indications that are not specifically dermatological, e.g. graft-versus-host disease or Crohn's disease, an experienced dermatologist trained in the use of photopheresis should therefore always be consulted.

In situ-targeting of dendritic cells with donor-derived apoptotic cells restrains indirect allorecognition and ameliorates allograft vasculopathy

Chronic allograft vasculopathy (CAV) is an atheromatous-like lesion that affects vessels of transplanted organs. It is a component of chronic rejection that conventional immuno-suppression fails to prevent, and is a major cause of graft loss. Indirect allo-recognition through T cells and allo-Abs are critical during CAV pathogenesis. We tested whether the indirect allo-response and its impact on CAV is down-regulated by in situ-delivery of donor Ags to recipient's dendritic cells (DCs) in lymphoid organs in a pro-tolerogenic fashion, through administration of donor splenocytes undergoing early apoptosis. Following systemic injection, donor apoptotic cells were internalized by splenic CD11c^hi CD8α⁺ and CD8⁻ DCs, but not by CD11c^int plasmacytoid DCs. Those DCs that phagocytosed apoptotic cells in vivo remained quiescent, resisted ex vivo-maturation, and presented allo-Ag for up to 3 days. Administration of donor apoptotic splenocytes, unlike cells alive, (i) promoted deletion, FoxP3 expression and IL-10 secretion, and decreased IFN-γ-release in indirect pathway CD4 T cells; and (ii) reduced cross-priming of anti-donor CD8 T cells in vivo. Targeting recipient's DCs with donor apoptotic cells reduced significantly CAV in a fully-mismatched aortic allograft model. The effect was donor specific, dependent on the physical characteristics of the apoptotic cells, and was associated to down-regulation of the indirect type-1 T cell allo-response and secretion of allo-Abs, when compared to recipients treated with donor cells alive or necrotic. Down-regulation of indirect allo-recognition through in situ-delivery of donor-Ag to recipient's quiescent DCs constitutes a promising strategy to prevent/ameliorate indirect allorecognition and CAV.

Experimental extracorporeal photopheresis inhibits the sensitization and effector phases of contact hypersensitivity via two mechanisms: generation of IL-10 and induction of regulatory T cells

Extracorporeal photopheresis (ECP) is used to treat immune-mediated diseases including transplant rejection and graft-vs-host-disease. An experimental murine model of ECP utilizing contact hypersensitivity (CHS) revealed that ECP inhibits the sensitization of CHS and induces regulatory T cells (Treg). In this study, we find that ECP inhibits not only the sensitization but also the effector phase of CHS, although Treg only inhibited sensitization. IL-10 was determined to be a critical component of the effector phase inhibition and also a driving force in developing Treg. Thus, we propose that the inhibition of the effector phase of CHS by ECP is a process that does not require Treg but may be mediated via enhanced IL-10 as suggested by the use of IL-10-deficient mice. This suggests that ECP has at least two mechanisms of action, one inhibiting the effector phase of CHS and one generating Treg, which in turn can inhibit CHS sensitization and is responsible for the transferable protection. Together, this may help explain the clinical benefits of ECP in prophylactic, acute, and therapeutic settings.

Repair of the lower and middle parts of the face by composite tissue allotransplantation in a patient with massive plexiform neurofibroma: a 1-year follow-up study

BACKGROUND

The risk to benefit ratio of face transplantation with a composite tissue allograft remains debatable, although this procedure is technically feasible. We report here a 1-year follow-up of a patient who underwent face transplantation with a composite tissue allograft.

METHODS

On Jan 21, 2007, a 29-year-old man with neurofibromatosis type 1 underwent resection of a massive plexiform neurofibroma diffusely infiltrating the middle and lower part of his face. The main goal was to restore both the cutaneous appearance and function of the face, including, in particular, control of orbicularis oculi and oris muscle contraction. The issues of immunosuppressive therapy, psychological outcome, and social reintergration were addressed, together with the monitoring of graft rejection by biopsies of the skin and mucosa.

FINDINGS

The initial postoperative course was uncomplicated. Two episodes of clinical rejection occurred on days 28 and 64. The second episode was associated with cytomegalovirus infection. Both episodes resolved favourably, with no further clinical signs of rejection, making the reduction of immunosuppressive treatment possible. A year after surgery, the functional outcome was very good, with successful sensory and motor reinnervation in the transplanted territory. Psychological recovery was excellent, with complete social reintegration.

INTERPRETATION

This case demonstrates the feasibility of surgically removing a large part of the face and replacing it with a composite tissue allograft. This facial repair procedure, which seems to have a satisfactory risk to benefit ratio, could be offered in rare and selected cases.

Extracorporeal photopheresis: Lighting the way to immunomodulation

Photopheresis, initially established as an effective treatment of cutaneous T-cell lymphoma, has in recent years also been used to treat chronic graft vs. host disease, heart transplant rejection, and several other conditions requiring immunosuppression. Despite reported beneficial results of this procedure in treatment of various conditions, randomized controlled clinical trials are lacking for the majority of suggested indications. Furthermore, the mechanisms of action of this procedure are still unclear. Deeper understanding of the molecular basis of photopheresis-based immunomodulation will allow better selection of patients to be treated and will facilitate development of novel, minimally toxic immunomodulatory treatments.

The first year post-heart transplantation: use of immunosuppressive drugs and early complications

A large number of heart transplants are performed annually in different transplant centers in the United States. This is partly because of the improved survival of patients who undergo cardiac transplantation, thus making it a more viable option in the management of end-stage heart failure. The survival benefit after heart transplantation is a result of newer immunosuppressive drug regimens and a better understanding of their effects and interactions. Several studies, mostly involving a small number of patients, describe use and comparison of the many distinct immunosuppressive drugs available to date. Interestingly, many transplant centers perform in-house typical induction treatment regimens because of their own experience and intra-institutional preference. This review summarizes current practices of immunosuppressive drug therapy in the first year post-heart transplant based on the available clinical evidence and discusses future options of heart transplant immunosuppressive drug therapies.

Extracorporeal Photochemotherapy as a Challenging Treatment for Cutaneous T-Cell Lymphoma, Acute and Chronic Graft-versus-Host Disease, Organ Rejection and T-Lymphocyte-Mediated Autoimmune Diseases

SUMMARY: 20 years ago, in 1987, Edelson and co-workers published their first report on the effectiveness of a new procedure, called extracorporeal photochemotherapy (ECP), in patients with advanced stage cutaneous T-cell lymphoma (CTCL). The positive response (>70% overall) achieved in those patients encouraged several groups to try out this new technology in other T-lymphocyte-mediated autoimmune diseases and a number of dermatological diseases, which sometimes gave conflicting results. In the following years, ECP obtained FDA approval as first line treatment in CTCL. In the 1990s ECP was applied to acute and chronic graft-versus-host disease (GvHD) refractory to conventional immunosuppressive therapy and proved to be effective in >60% of cases of this larger patient population. Today, although the effectiveness of ECP in GvHD is generally acknowledged, this is mainly based on retrospective or observational studies, as data from large, randomized multicenter trials, has yet to be published. Moreover, ECP's real mechanism of action and optimal treatment schedule are still under investigation. The aim of this review is to summarize knowledge acquired to date about ECP.

Outcomes 18 months after the first human partial face transplantation

BACKGROUND

We performed the first human partial face allograft on November 27, 2005. Here we report outcomes up to 18 months after transplantation.

METHODS

The postsurgical induction immunosuppression protocol included thymoglobulins combined with tacrolimus, mycophenolate mofetil, and prednisone. Donor hematopoietic stem cells were infused on postoperative days 4 and 11. Sequential biopsy specimens were taken from a sentinel skin graft, the facial skin, and the oral mucosa. Functional progress was assessed by tests of sensory and motor function performed monthly. Psychological support was provided before and after transplantation.

RESULTS

Sensitivity to light touch, as assessed with the use of static monofilaments, and sensitivity to heat and cold had returned to normal at 6 months after transplantation. Motor recovery was slower, and labial contact allowing complete mouth closure was achieved at 10 months. Psychological acceptance of the graft progressed as function improved. Rejection episodes occurred on days 18 and 214 after transplantation and were reversed. A decrease in inulin clearance led to a change in immunosuppressive regimen from tacrolimus to sirolimus at 14 months. Extracorporeal photochemotherapy was introduced at 10 months to prevent recurrence of rejection. There have been no subsequent rejection episodes. At 18 months, the patient is satisfied with the aesthetic result.

CONCLUSIONS

In this patient who underwent the first partial face transplantation, the functional and aesthetic results 18 months after transplantation are satisfactory.

Photopheresis in pediatric graft-versus-host disease after allogeneic marrow transplantation: clinical practice guidelines based on field experience and review of the literature

BACKGROUND

Extracorporeal photochemotherapy (ECP) gives positive results in the management of graft-versus-host disease (GVHD), but in children, specific difficulties can outweigh this benefit. These difficulties must be taken into consideration when establishing a standardized reproducible procedure for implementation under a quality management plan.

STUDY DESIGN AND METHODS

Twenty-seven children underwent ECP for severe acute GVHD (aGVHD) or chronic GVHD (cGVHD) after allogeneic marrow transplantation. Data were collected prospectively, with particular emphasis placed on technical, biologic, immunologic, clinical, and long-term follow-up issues.

RESULTS

The 27 children underwent a total of 750 sessions. Mononuclear cells were collected on a commercially available apheresis system (COBE Spectra, Gambro BCT). Overall survival was 73 percent, and ECP led to significant improvement in 21 of the 27 patients (11 with complete response and 10 with partial response, i.e., >50% of organ involvement). Tolerance was good overall, the main limiting factors being vascular access and the psychological impact of repeated apheresis procedures. Children weighing less than 25 kg were not more susceptible to side effects.

CONCLUSION

A specifically pediatric-dedicated and -experienced team faces only limited difficulties when treating children with GVHD by ECP. Overall, ECP is efficient and well tolerated. Our experience was therefore pooled together with available pediatric data to establish clinical practice guidelines. These guidelines consider ECP as a first-line therapy in Grade IV aGVHD (in association with conventional pharmacologic approaches) and limited cGVHD and as a second-line therapy in steroid-resistant Grades II to III aGVHD and extensive cGVHD.

Induction of gamma-globin mRNA, erythroid differentiation and apoptosis in UVA-irradiated human erythroid cells in the presence of furocumarin derivatives

Psoralens, also known as furocoumarins, are a class of photosensitizers largely used in the therapy of various skin diseases. In this study we have evaluated the combined effects of UVA irradiation and furocoumarins derivatives on (a) erythroid differentiation and apoptosis of human leukemia K562 cells and (b) globin gene expression in cultures of human erythroid progenitors derived from the peripheral blood. To prove the activity of a series of linear and angular furocoumarins derivatives, we employed the human leukemia K562 cell line and the two-phase liquid culture procedure for growing erythroid progenitors. Quantitative real-time reverse transcription polymerase-chain assay (Q-RT-PCR) was employed for quantification of the accumulation of globin mRNAs. The results obtained demonstrate that both linear and angular furocoumarins are strong inducers of erythroid differentiation of K562 cells. From a preliminary screening, we have selected two derivatives, 5-methoxypsoralen (5-MOP) and trimethylangelicin (TMA), for which we have investigated their mechanism of action. The cell cycle analysis showed that these derivatives induce, after irradiation, a cell cycle arrest in the G2/M phase, followed by apoptosis. Mitochondrial depolarisation and caspases activation seem to be involved in the mechanism of cell death. In erythroid precursor cells, psoralens in combination with UVA irradiation, stimulate at very low concentrations a preferential increase of gamma-globin mRNA. Altogether, these data suggest that psoralen derivatives warrant further evaluation as potential therapeutic drugs in beta-thalassemia and sickle cell anemia.

Extracorporeal photophoresis increases sensitivity of monocytes from patients with graft-versus-host disease to HLA-DR-mediated cell death

BACKGROUND

Graft-versus-host disease (GVHD) remains a cause of long-term morbidity after allogeneic hematopoietic stem cell transplantation, and recent studies indicate that extracorporeal photophoresis (ECP) is useful for treatment of steroid-refractory GVHD although the mechanisms are unclear. Antigen-presenting cells (APCs) such as dendritic cells have a central role in GVHD, and apoptosis of APCs by HLA-DR monoclonal antibody (MoAb) has been documented in vitro and in vivo. Monocytes have been identified as precursors of dendritic cells in vivo and particularly under conditions of inflammation.

STUDY DESIGN AND METHODS

This study examined whether ECP altered the survival of peripheral blood monocytes from patients with GVHD, monocyte apoptosis after engagement of HLA-DR antigens with MoAb, and monocyte apoptosis after allointeraction with primary CD4+ T lymphocytes. Samples from patients from two centers were studied.

RESULTS

It is reported here that ECP induced apoptosis of monocytes over a period of at least 48 hours. ECP also clearly increased cell death of monocytes after engagement of HLA-DR antigens with MoAb. In contrast, engagement of HLA-DR by allointeraction failed to induce significant cell death of monocytes, and this was unaltered by ECP treatment.

CONCLUSION

These data reveal that monocytes from patients with GVHD are sensitive to HLA-DR-mediated apoptosis and that ECP treatment increases sensitivity to both spontaneous and HLA-DR-mediated apoptosis. Therefore, ECP treatment in combination with HLA-DR MoAbs could rapidly deplete monocytes and thereby reduce the contribution of monocyte-derived dendritic cells to GVHD.

Extracorporeal photopheresis with permanent subcutaneous right atrial catheters

BACKGROUND

Adequate peripheral venous access is crucial for successful extracorporeal photopheresis (ECP). As this approach is not always feasible in older patients and patients with graft-versus-host disease, central venous catheters play an increasing role in providing long-term vascular access for ECP.However, not all catheters are able to deliver the minimum flow rate of 7 ml/min for ECP.

PATIENTS AND METHODS

Eight different permanent subcutaneous right atrial catheters were connected in vitro to the UVAR-XTS photopheresis system and median flow rates were determined. In addition, in vivo flow rates of patients who received ECP, using either peripheral or central venous access, were determined.

RESULTS

Hemodialysis catheters with an internal diameter of 2.0 or 1.5 x 3.5 mm and a length up to 48 cm provided in vitro flow rates of 27-28 ml/min, almost identical to a peripheral access needle. Central venous catheters with a length of over 90 cm reached flow rates below 7 ml/min and are impractical for ECP. The analysis of 308 ECP collection cycles with peripheral vascular access revealed an average flow rate of 31.5 +/- 6.4 ml/min. Only permanent subcutaneous right atrial catheters made for hemodialysis provided similar flow rates (Quinton PermCath Dual Lumen) (33.7 +/- 4.7 ml/min, n = 198).

CONCLUSIONS

Permanent subcutaneous hemodialysis catheters with a length of maximally 48 cm achieve optimal flow rates for ECP. They represent therefore the central venous access of choice in patients with inadequate peripheral vascular access.

Cell death recognition model for the immune system

It is essential for the immune system to recognize markers or understand rules required for discriminating antigens that should be actively responded to from those be tolerated. Although the classic self-nonself theory over the past five decades has been challenged by "danger" model and "infectious nonself" model, etc., no theories could fit for all. Cell death is important not only for its role in homeostasis, but also for its decisive effects on the immune responses. Different ways of cell death, apoptosis or necrosis, transmit fundamentally opposite driving forces for the immune system, inducing tolerance or initiating adaptive immune responses. The progress in understanding phagocytosis and process of apoptotic and necrotic cells leads the author to propose "cell death" recognition model for the immune system. Four principles are important in this model. First, only antigens shedding from apoptotic or necrotic cells rather than those from healthy cells, can be presented to naïve T cells. Second, either apoptotic cells or necrotic cells, but not healthy cells, can attract phagocytes, namely dendritic cells (DC) or macrophages that are also antigen presenting cells (APC), to scavenge dead cells. Third, macrophages or DC residing in non-lymphoid tissues phagocytose dying/dead cells, migrate to lymphoid tissues and present antigens to naïve T cells there. Fourth, tolerance or adaptive responses are not dependent on whether the antigens are self or nonself, but on the ways of cell death during antigen presentation. Importantly, tolerance and adaptive immunity are all dominant responses and the impact of cell death on immune responses is a dynamic balance between them. "Cell death" recognition model could more easily explain various immune phenomena, including infection, self tolerance and autoimmunity, tumor immunity as well as transplant rejection. Investigation into the roles and mechanisms of cell death mediated immune responses and finding out key modulators will prompt better understanding the ways of immune recognition and provide novel strategies for the management of autoimmunity, tumors, infections as well as transplantation.

Induction of regulatory T cells after prophylactic treatment with photopheresis in renal transplant recipients

Extracorporeal photopheresis (ECP), originally used to treat cutaneous T-cell lymphoma, also has been applied to the therapy of transplant rejection. Our aim was to investigate the biologic response in two children who underwent kidney transplantation with ECP as prophylactic treatment. They received conventional immunosuppressive therapy and ECP immediately after transplantation: six applications over the course of 3 weeks. During a 12-month follow-up, the clinical course was favorable in both patients; renal histology was normal 6 months after transplantation. When compared with four transplanted controls, the ECP-treated patients showed lower tumor necrosis factor-alpha serum levels in the short-term and a marked increase of Foxp3-positive T-regulatory cells. T-regulatory cells were still higher than in the controls 1 year after transplantation. These preliminary results suggest that the addition of ECP to standard immunosuppressive therapy induces a tolerogenic shift in the immune system of kidney transplanted patients and may pave the way to preventing chronic rejection.

A new device to study ex-vivo the effects of extracorporeal photochemotherapy on the immune system

Extracorporeal photochemotherapy (ECP) is a medical procedure effective in the treatment of several different T-cell mediated diseases such as cutaneous T-cell lymphoma and Graft-versus-Host Disease. During ECP treatment the patient's blood is processed by means of a cell separator to collect leukocytes (leukapheresis), mostly lymphocytes and monocytes, which are then incubated with the photoactive drug 8-methoxypsoralen (8-MOP), exposed to ultraviolet-A light (UV-A) and reinfused to the patient. It has been suggested that during ECP not only UV-A irradiation but also changes in the environmental condition may be relevant. Although ECP has been shown to have an in-vivo immunomodulatory effect, the mechanisms through which ECP exerts its effect remain elusive. One of the reasons for this incomplete knowledge is the absence of a reliable model for ECP. In order to investigate the effect of ECP on the peripheral immune system, we developed a new device which mimics the complete ECP cycle including blood transit through the cell separator. Peripheral blood samples (50ml) were obtained from volunteers and processed using a peristaltic pump. Peripheral blood mononuclear cells (PBMC) were then collected and treated with 8-MOP and UV-A under the same conditions used for the patients' therapy. Using this strategy we investigated 8-MOP, UV-A and their combined effect on the production of the pro-inflammatory cytokines interferon-gamma (IFN-gamma), interleukine-2 (IL-2) and tumor necrosis factor-alpha (TNF-alpha) in PBMC with and without polyclonal stimulation. We firstly demonstrated that our device does not affect total red and white blood cell counts. After 8-MOP and UV-A irradiation a significant decrease was observed in both activated CD4(+) and CD8(+) T lymphocytes producing IFN-gamma, IL-2 and TNF-alpha. Our findings are in line with those previously obtained in humans after complete ECP treatment, thus suggesting that our newly developed device is suitable for investigating the mechanism of action of ECP ex-vivo.

Extracorporeal Photochemotherapy for the Treatment of Chronic Graft-Versus-Host Disease: Trend for a Possible Cell Dose-Related Effect?

Extracorporeal photochemotherapy (ECP) has been progressively introduced into the treatment of both acute and chronic graft-versus-host disease (cGvHD) over the last decade. Nevertheless, its mechanisms of action, as well as the optimal treatment schedule, have not yet been defined. We retrospectively analyzed 25 patients with cGvHD unresponsive to conventional treatments who underwent ECP from 1997 until 2005. The impact of various factors (such as treated and infused nucleated cells, time from transplantation and cGvHD onset, and time from cGvHD and ECP treatment) on the probability of no response to ECP was therefore investigated. A positive response to ECP was achieved in 80% of the patients, after a median of 19 ECP treatments (with a range of 8-38). Eighteen out of the 20 patients responsive to the treatment maintained their response for a median of 30 months. We mainly focused on clinical response and yield composition. The analysis on mononuclear cell (MNC) dose suggested that an increase of MNC dose/kg b.w. (body weight) induced a decrease in the odds of treatment failure, and that, if the MNC dose infused was at least 100 x 10(6)/kg b.w. per ECP treatment, a more positive and longer-lasting response was achieved. Moreover, the mean dose of treated and infused monocytes x 10(6)/kg b.w./ECP did not account for a clear dose-related effect. These findings may eventually result in a more patient-tailored approach to ECP. Prospective multicenter trials should be designed to investigate the real impact of MNC dose on ECP responsiveness.