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

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. This elaborate process had been undertaken every 7 years resulting in three prior publications in 1986, 1993, and 2000 of "The ASFA Special Issues." This article is the integral part of the Fourth ASFA Special Issue. The Fourth ASFA Special Issue is significantly modified in comparison to the previous editions. A new concept of a fact sheet has been introduced. The fact sheet succinctly summarizes the evidence for the use of therapeutic apheresis. A detailed description of the fact sheet is provided. The article consists of 53 fact sheets devoted to each disease entity currently categorized by the ASFA. Categories I, II, and III are defined as previously in the Third Special Issue. However, a few new therapeutic apheresis modalities, not yet approved in the United States or are currently in clinical trials, have been assigned category P (pending) by the ASFA Clinical Categories Subcommittee. The diseases assigned to category IV are discussed in a separate article in this issue.

Avoiding calcineurin inhibitors in the early post-operative course in high-risk liver transplant recipients: The role of extracorporeal photopheresis

The aim of this work is to report on the results of a single-center, prospective study on the feasibility of calcineurin-inhibitor (CNI)-staggered immunosuppression by use of extracorporeal photopheresis (ECP) in liver transplant (LT) recipients at risk of renal and neurological complications. Patients were matched on a 1:1 basis with historical controls on standard CNI immunosuppression. ECP patients were treated with ECP plus antimetabolites and/or steroids, while CNIs were withheld until clinically indicated. Thirty-six patients were evaluated: 18 ECP patients and 18 controls. ECP was tolerated in 100% of cases. CNI were introduced at a median of 8 days (4-55) in 17 ECP patients, while one patient was on a fully CNI-sparing regimen 22 months after LT. Acute rejection occurred in 27.7% patients in ECP (5/18) versus 16.7% in controls (3/18) (P = ns) with a shorter time to rejection in ECP (36 +/- 31.3 days vs. 83.6 +/- 65.6 days; P = ns). All rejection episodes were amenable to medical treatment. Neurological and renal complications occurred in 22.2% (4/18) of patients in either group, but led to in-hospital mortality in 3 patients among controls versus 1 in ECP (P = ns). One-, 6-, and 12-month survival rates were 94.4, 88.1, and 88.1% in ECP versus 94.4, 77.7, and 72.2% among controls (P < 0.0001). ECP seems to allow for management of high-risk LT recipients in the early post-transplant course and reduction of CNI-related mortality. Continued data validation is favored to assess the impact of ECP on long-term graft and patient survival.

Technology insight: ECP for the treatment of GvHD--can we offer selective immune control without generalized immunosuppression?

Hematopoietic stem-cell transplantation remains an important curative therapy for many conditions and its use is increasing annually. Graft-versus-host disease (GvHD) is the major cause of mortality and suffering following allogeneic hematopoietic stem-cell transplantation. Conventional treatments are associated with multiple side effects and are often ineffective. New therapeutic approaches for the control of GvHD are desperately required. Extracorporeal photochemotherapy (ECP) was developed in the 1970s for the treatment of cutaneous T-cell lymphoma and was approved by the FDA as the first selective immunotherapy for a cancer. ECP has also proved an effective therapy for immune-related conditions, particularly GvHD, even in patients refractory to conventional therapies. The treatment involves the mechanical separation of circulating white cells, which are exposed to psoralen and UVA light and then returned to the patient. ECP is extremely well tolerated with minimal side effects and is not associated with the increased rates of infection or relapse of malignant disease typical of conventional immunosuppressive agents. Thus, ECP appears to offer selective immune modulation without generalized immunosuppression, but its mechanism of action remains poorly understood. This review discusses the development of ECP, its use in the treatment of GvHD, as well as current theories of its mechanism of action.

Refractory acute renal allograft rejection successfully treated with photopheresis

INTRODUCTION

Acute rejection episodes still occur in spite of modern immunosuppressive protocols. We present seven patients with biopsy-proven acute rejections after kidney transplantation refractory to repeated pulses of high-dose steroids and antithymocyte globulin (ATG) or OKT-3, but responsive to photopheresis therapy.

METHODS

Photopheresis is a nontoxic immunomodulatory, apheresis-based treatment with no general immunosuppressive action. Rather, it suppresses specific pathogenic T-cell clones. During photopheresis mononuclear leukocytes are collected from the patient using centrifugation technique, treated with a photosensitizing agent, irradiated, and subsequently retransfused.

RESULTS

All patients tolerated the treatment well, with no notable side effects. At the 12-month follow-up the median creatinine had decreased to 161 mumol/L compared to 282 mumol/L at the start of photopheresis and at the last follow-up 12 to 43 months after transplantation all patients still had functioning grafts. In five of the seven cases there had been a significant improvement in renal function, whereas in two of the patients the renal function remained stable but without a decrease in creatinine.

CONCLUSIONS

It is our experience that the prognosis for renal allografts with acute rejection unresponsive to conventional antirejection treatment (ie, repeated pulses of methylprednisolone and ATG or OKT-3) is very poor. Therefore, we conclude that the photopheresis treatment contributed to the favorable outcome in this small group of patients. We are presently designing a prospective randomized study to further evaluate the effect of photopheresis after renal transplantation.

Rejection With Hemodynamic Compromise: Objective Evidence for Efficacy of Photopheresis

BACKGROUND

Photopheresis therapy (photo) has been advocated as a therapy to improve outcome after recalcitrant or severe rejection, but objective evidence of a beneficial effect has been elusive. This study examined the hypothesis that photo provides protection against rejection, rejection with hemodynamic compromise (HC), and death from rejection after cardiac transplantation.

METHODS

Between 1990 and 2003, 36 adult patients (from 343 adult transplant recipients) received at least 3 months of photo (2-day treatment every 3 to 6 weeks for a target of 18 months) after HC rejection (n = 12), recurrent/recalcitrant rejection (n = 20), or as prophylaxis in the presence of anti-donor antibodies (n = 4). Survival and risk factors were examined by analysis using multivariate hazard function modulated renewal function.

RESULTS

Patients selected for photo were at greater risk for rejection (p < 0.0001) and HC rejection (p < 0.0001) than non-photo patients. After 3 months of photo therapy, rejection risk was decreased (p = 0.04). More importantly, the hazard for subsequent HC rejection or rejection death was significantly reduced toward the risk-adjusted level of lower-risk non-photo patients (p = 0.006).

CONCLUSIONS

This study provides objective evidence that photo reduces the risk of subsequent HC rejection and/or death from rejection when initiated for patients with high rejection risk. Photopheresis is recommended as an important therapeutic modality after rejection with hemodynamic compromise, although further studies are needed to define the precise mechanism of the effect and the potential for benefit in other patient sub-sets.

The immune regulatory effect of apoptotic cells and exosomes on dendritic cells: its impact on transplantation

Dendritic cells (DC) are professional antigen (Ag) presenting cells (APC) that trigger the anti-donor T-cell response that causes allograft rejection. During the past decade several laboratories have employed in vitro generated DC with tolerogenic potential for prolongation of allograft survival. This minireview describes the development of a second-generation of DC-based strategies for transplantation tolerance based on the delivery in situ of donor allogeneic (allo)-Ag to quiescent DC of graft recipients by means of donor-derived apoptotic cells or exosomes. Donor leukocytes in early apoptosis are rich in allo-Ag, are internalized efficiently by recipient DC in vivo and deliver immunosuppressive signals to DC. Administration (i.v.) of donor apoptotic leukocytes prolongs bone marrow engraftment and cardiac allografts survival in mice by exerting a profound down-regulatory effect on the anti-donor T-cell response. Exosomes are nanovesicles (<100 nm) produced by different cell types, including APC. DC-derived exosomes are rich in major histocompatibility complex (MHC) molecules that can be employed to target DC in situ. Once i.v. injected, exosomes carrying donor MHC molecules are captured by recipient's DC and prolong allograft survival in rodents. The use of the regulatory functions of apoptotic cells and exosomes may be useful tools to develop new strategies for transplantation tolerance.

Quo vadis haemapheresis. Current developments in haemapheresis

The techniques of haemapheresis originated in the development of centrifugal devices separating cells from plasma and later on plasma from cells. Subsequently membrane filtration was developed allowing for plasma-cell separation. The unspecificity of therapeutic plasma exchange led to the development of secondary plasma separation technologies being specific, semi-selective or selective such as adsorption, filtration or precipitation. In contrast on-line differential separation of cells is still under development. Whereas erythrocytapheresis, granulocytapheresis, lymphocytapheresis and stem cell apheresis are technically advanced, monocytapheresis may need further improvement. Also, indications such as erythrocytapheresis for the treatment of polycythaemia vera or photopheresis though being clinically effective and of considerable importance for an appropriate disease control are to some extent under debate as being either too costly or without sufficient understanding of the mechanism. Other forms of cell therapy are under development. Rheohaemapheresis as the most advanced technology of extracorporeal haemorheotherapy is a rapidly developing approach contributing to the treatment of microcirculatory diseases and tissue repair. Whereas the control of a considerable number of (auto-) antibody mediated diseases is beyond discussion, the indication of apheresis therapy for immune complex mediated diseases is quite often still under debate. Detoxification for artificial liver support advanced considerably during the last years, whereas conclusions on the efficacy of septicaemia treatment are debatable indeed. LDL-apheresis initiated in 1981 as immune apheresis is well established since 24 years, other semi-selective or unspecific procedures, allowing for the elimination of LDL-cholesterol among other plasma components are also being used. Correspondingly Lp(a) apheresis is available as a specific, highly efficient elimination procedure superior to techniques which also eliminate Lp(a). Quality control systems, more economical technologies as for instance by increasing automation, influencing the over-interpretation of evidence based medicine especially in patients with rare diseases without treatment alternative, more insight into the need of controlled clinical trials or alternatively improved diagnostic procedures are among others tools ways to expand the application of haemapheresis so far applied in cardiology, dermatology, haematology, immunology, nephrology, neurology, ophthalmology, otology, paediatrics, rheumatology, surgery and transfusion medicine.

Photopheresis in solid organ transplant rejection

Photopheresis has become a key component in the therapeutic armamentarium of cutaneous T-cell lymphoma, graft-versus-host disease following stem cell transplant, and allograft rejection of solid organs such as heart. Although it is considered a new treatment modality in its present form, the field of phototherapy dates back thousands of years. In this review, the reader will learn more about the history of photopheresis and how it became a therapeutic alternative for patients with solid organ transplants. An extensive literature search will highlight the evidence-based benefits of photopheresis (or lack thereof). A discussion of the mechanism of action of photopheresis and the technical aspects of the procedure will also be covered. Since photopheresis may be the best tolerated form of immunomodulation, current promising, albeit preliminary data on its efficacy warrant further investigation and understanding.

The immunological effect of photopheresis in children with newly diagnosed type 1 diabetes

Photopheresis has been claimed to have immune-modulating effects, but the mechanisms of action are unknown. This study investigated the immune effect of photopheresis in children with type 1 diabetes, with a focus on the balance of Th1- and Th2-like cytokines. Ten children with newly diagnosed type 1 diabetes (10-17 y) were treated with five double treatments of photopheresis and 10 children matched for disease, age, and gender were given placebo tablets and sham pheresis. Expression of IFN-gamma and IL-4 mRNA was determined by real-time reverse-transcriptase polymerase chain reaction (RT-PCR) and secretion of IFN-gamma, IL-10, and IL-13 in cell-culture supernatants by ELISA after stimulation with glutamic acid decarboxylase (GAD65) (a.a. 247-279), the ABBOS peptide (a.a. 152-169), insulin, phytohemagglutinin (PHA), and keyhole limpet hemocyanin (KLH). Photopheresis changed antigen-stimulated immune balance in line with a Th2-like shift. Thus, the ratio of IFN-gamma/IL-4 mRNA expression after in vitro stimulation with a peptide of the autoantigen GAD65 was reduced after treatment in the photopheresis group. The IFN-gamma/IL-4 mRNA expression ratio after in vitro stimulation with insulin was also lower in children treated with photopheresis compared with the placebo group. Photopheresis has an immune-modulating effect in children with type 1 diabetes, causing a Th2-like deviation.

Evidence-based practice of photopheresis 1987-2001: a report of a workshop of the British Photodermatology Group and the U.K. Skin Lymphoma Group

Photopheresis or extracorporeal photochemotherapy (ECP) is a novel immunomodulatory therapy which involves separation of the patient's leucocyte-rich plasma, followed by ex vivo administration of a photosensitizer and ultraviolet A radiation, before reinfusion. ECP has been used successfully for the treatment of cutaneous T-cell lymphoma (CTCL: Sézary syndrome), graft-versus-host disease (GVHD) and cardiac transplant rejection. ECP has a dose-sparing effect on concurrent immunosuppressive therapy. The procedure induces apoptosis of the irradiated lymphocytes, but the exact mechanism by which ECP exerts its therapeutic effect in these different conditions is uncertain. The treatment has very few adverse effects and in particular is not associated with an increased incidence of opportunistic infections. The evidence for the efficacy of ECP has been appraised by a combined British Photodermatology Group and U.K. Skin Lymphoma Group workshop on the basis of evidence published up to the end of 2001 and on the consensus of best practice. There is fair evidence for the use of ECP in erythrodermic CTCL and steroid-refractory GVHD, but randomized controlled studies are needed. There is good evidence supporting the use of ECP in preventing cardiac rejection following transplantation. Randomized controlled trials have also shown a therapeutic benefit in type 1 diabetes mellitus, but the inconvenience associated with the procedure outweighed the clinical benefit. There is fair evidence not to use ECP for the treatment of systemic sclerosis and multiple sclerosis, and good evidence not to use ECP for other forms of CTCL.

Intravenous Infusion of Syngeneic Apoptotic Cells by Photopheresis Induces Antigen-Specific Regulatory T Cells

The basis of extracorporeal photopheresis is the reinfusion of leukocytes previously exposed to 8-methoxypsoralen (8-MOP) and UVA radiation. It has been approved for the palliative treatment of cutaneous T cell lymphoma and has reported benefits in autoimmune diseases, transplant rejection, and graft-vs-host disease. However, the underlying mechanism of photopheresis remains unresolved. Because UVB radiation can cause immune tolerance via induction of regulatory T cells, we studied whether photopheresis exerts a similar effect extracorporeally. Therefore, we established a model of photopheresis using a murine model of contact hypersensitivity. Splenocytes and lymph node cells of mice that were sensitized with dinitrofluorobenzene were exposed to 8-MOP plus UVA in vitro. Intravenous injection of these cells into naive mice caused inhibition of a hapten immune response, which was lost upon depletion of CD11c(+) cells but not T cells. Mice that received untreated cells or cells exposed to UVA or 8-MOP alone were not affected. Inhibition was cell-mediated and Ag-specific as demonstrated by transfer of tolerance from the primary recipients into naive animals, which could, however, properly respond to the unrelated hapten oxazolone. Transfer activity was lost when cells were depleted of CD4(+) or CD25(+) subpopulations. These data suggest that photopheresis exerts its immunomodulatory effects via the induction of Ag-specific regulatory T cells.

Prospective study of extracorporeal photopheresis in steroid-refractory or steroid-resistant extensive chronic graft-versus-host disease: analysis of response and survival incorporating prognostic factors

We enrolled 25 patients with extensive, steroid-refractory chronic graft-versus-host disease (cGVHD) in a prospective trial evaluating the efficacy of extracorporeal photophoresis (ECP) in both skin and visceral cGVHD. The median time from transplant to initiation of ECP was 790 days. ECP was administered for 2 consecutive days every 2 weeks in 17 patients and once a week in eight patients until best response or stable disease. The median duration of therapy was 9 months (range 3-24 months). In all, 20 patients had improvement in cutaneous GVHD and six had healing of oral ulcerations. Steroid sparing or discontinuation of immunosuppressive medications was possible in 80% of patients. Response rates were similar between patients receiving treatment weekly vs every 2 weeks and in patients commencing ECP less than vs greater than 18 months from transplant (70 vs 66%). When patients were stratified based on the Akpek prognostic score, there was no difference in overall response between the favorable (Akpek score<2.5) and unfavorable risk groups, but patients with progressive onset cGVHD tended to have a higher response than those with de novo onset. In summary, we report improvement in skin and/or visceral cGVHD in 71% overall and 61% of high-risk patients.

The Immunological Effects of Extracorporeal Photopheresis Unraveled: Induction of Tolerogenic Dendritic Cells In Vitro and Regulatory T Cells In Vivo

Extracorporeal photopheresis (ECP) may represent an alternative to immunosuppression, as a means of reducing rejection after thoracic organ transplantation. The mechanism by which ECP exerts its protective effects has, until now, remained elusive. We analyzed peripheral blood mononuclear cells of four children with chronic heart and lung transplant rejection, who received ECP in addition to conventional immunosuppressive treatment. The effects of ECP were evaluated at each cycle, comparing blood samples from the same patient collected before and after treatment. In vitro, peripheral blood mononuclear cells treated with ECP undergo apoptosis and are phagocytosed by immature dendritic cells, which, in turn, acquire a tolerogenic phenotype. The frequency of T cells, with a regulatory phenotype and strong suppressive activity, was significantly increased in the blood of ECP-treated patients. The immunomodulatory effects of ECP may be explained by its ability to increase the frequency of regulatory T cells with inhibitory action on transplant immune rejection.

Photopheresis for the treatment of refractory renal graft rejection

Acute rejection episodes still occur after kidney transplantation in spite of modern immunosuppressive protocols including combined tacrolimus, mycophenolate mofetil, and prednisolone. The authors present seven cases of biopsy-proven acute rejection after kidney transplantation refractory to conventional rejection therapy with repeated pulses of high-dose steroids followed by polyclonal or monoclonal antibodies that responded well to photopheresis treatment. Photopheresis is an atoxic immunomodulatory apheresis-based treatment with no generalized immunosuppressive action; rather, it is directed at suppressing donor-specific T-cell clones. At the last follow-up, 9 to 43 months after transplantation, all patients had functioning grafts, with serum creatinine levels ranging from 105 to 312 microM. The authors conclude that photopheresis treatment contributed to the favorable outcome. Therefore, the authors are presently designing a prospective, randomized trial to evaluate the effect of photopheresis as an adjuvant prophylactic treatment after renal transplantation.

Anti-inflammatory effects of UV-irradiated lymphocytes: induction of IL-1Ra upon phagocytosis by monocyte/macrophages

One of the mechanisms proposed to explain immunomodulatory actions of ultraviolet light (UV) is production of endogenous anti-inflammatory cytokines. The purpose of the present study is to evaluate how UV light affects the production of IL-10 and IL-1Ra and to provide insight as to the role of phagocytosis of apoptotic lymphocytes in this process. Cytokine production was evaluated in a coculture system consisting in UV-treated lymphocytes in the presence of autologous PBMC. The impact of phagocytosis was tested by two blocking agents cytochalasin E and anti-CD36 mAb. The apoptotic process affecting irradiated lymphocytes was progressive, culminating at 48 h. To achieve significant cytokine production, irradiated lymphocytes were incubated overnight at 37 degrees C. Coculture of apoptotic lymphocytes with autologous PBMC resulted in a significant increase of IL-1Ra mRNA (+340%; P = 0.001) and protein (+72%; P = 0.001) production. This synthesis was blocked by cytochalasin E but upregulated by CD36 receptor cross-linking. Our study shows that UV light induces lymphocyte apoptosis followed by its phagocytosis by monocyte/macrophages, a step that preferentially activates IL-1Ra.

Allograft tolerance induced by donor apoptotic lymphocytes requires phagocytosis in the recipient

Cell death through apoptosis plays a critical role in regulating cellular homeostasis. Whether the disposal of apoptotic cells through phagocytosis can actively induce immune tolerance in vivo, however, remains controversial. Here, we report in a rat model that without using immunosuppressants, transfusion of apoptotic splenocytes from the donor strain prior to transplant dramatically prolonged survival of heart allografts. Histological analysis verified that rejection signs were significantly ameliorated. Splenocytes from rats transfused with donor apoptotic cells showed a dramatically decreased response to donor lymphocyte stimulation. Most importantly, blockade of phagocytosis in vivo, either with gadolinium chloride to disrupt phagocyte function or with annexin V to block binding of exposed phosphotidylserine to its receptor on phagocytes, abolished the beneficial effect of transfused apoptotic cells on heart allograft survival. Our results demonstrate that donor apoptotic cells promote specific allograft acceptance and that phagocytosis of apoptotic cells in vivo plays a crucial role in maintaining immune tolerance.

Effect of photopheresis on lymphocyte population in children with newly diagnosed type 1 diabetes

In recent years photopheresis has been claimed to be an effective form of immunomodulation. It has also been shown to have an effect on the disease process at the onset of type 1 diabetes. In a double-blind, placebo-controlled randomized study, we analyzed if the effect of photopheresis in children with newly diagnosed diabetes is related to changes in the balance of lymhocyte populations. We also analyzed if lymphocyte subsets were related to recent infection, mild or aggressive disease manifestations, heredity, or gender. Nineteen children received active treatment with photopheresis, while 21 children received sham pheresis (placebo group). No influence of a history of previous infection, heredity, or certain clinical parameters on lymphocyte subsets was found. At the onset of type 1 diabetes, girls showed a higher proportion and a larger number of T cells (CD3+) and T-helper cells (CD4+) and a higher proportion of naïve CD4+ CD45RA+ cells. In the placebo group, an increase in the number of subsets with the activated phenotype in both the CD4(CD29+) and the CD8 (CD11a+) compartments was noted during the course of the study. These changes did not occur in the photopheresis group. No relation between lymphocyte subsets and clinical outcome was found 1 year after the treatment with photopheresis. In conclusion, we found no major effect of photopheresis on lymphocyte populations in a group of children with newly diagnosed type 1 diabetes. However, in the placebo group the proportions of activated CD4 and CD8 cells increased over time. Since these changes did not occur in the actively treated group, our findings suggest that photopheresis may have some suppressive effects.

[Cell therapy for cancer treatment in children]

The cure rate for cancer in children is currently almost 75%. This rate has remained fairly constant over the past few years, which suggests that the limits of today's curative treatment potential have been reached. The development of cell therapy techniques opens up new therapeutic possibilities in paediatric oncology. Here, we deal both with a number of cell therapy techniques, which have already proved their efficacy in children, and other more innovative approaches, which require validation. Examples of the use of autologous and allogeneic cells are described. Clinical studies and their results, while often preliminary, are reported. The importance of well run clinical research, a clear and progressive legal framework and the necessary substantial economic support for the development of cell therapy are underlined.

Ultraviolet light-induced regulatory (suppressor) T cells: an approach for promoting induction of operational allograft tolerance?

Ultraviolet (UV) light is known to induce skin cancers by causing DNA gene mutations and inducing immunosuppression. Taking advantage of these immunosuppressive capacities, UV light has been used, with different modalities, as an immunosuppressive therapy in a variety of diseases including allograft rejection and graft-versus-host disease. Phototherapy includes UVB irradiation, UVA irradiation, oral psoralen (+)UVA irradiation (PUVA), photodynamic therapy, and extracorporeal photopheresis, which consists of infusion of UVA-irradiated autologous leukocytes collected by apheresis and incubated with 8-methoxypsoralen. According to numerous experimental models and human data, there is increasing evidence that UVB irradiation and extracorporeal photopheresis can induce regulatory T cells and anticlonotypic activity. These therapies induce apoptosis of activated T cells or of extracorporally treated mononuclear cells, and up-regulate the expression of costimulary molecules and adhesion molecules on antigen presenting cells. UVB- or UVA-induced apoptotic cells could secrete immune suppressive cytokines (interleukin (IL)-4, IL-10). The processing and presentation of apoptotic T cell antigens from clones of pathogenic T cells by activated antigen presenting cells might explain the induction of systemic anticlonotypic activity by photopheresis. This induction of cell-mediated suppressive activity opens up future prospects with the aim of expanding regulatory T cells and/or anticlonotypic activity, especially by photopheresis in organ and cell transplantation.

Immunosuppression in Pediatric Heart Transplantation: 2003 and Beyond

Advances in immunosuppressive therapy have contributed to the improved long-term survival of pediatric heart transplant recipients over the past two decades. The introduction of cyclosporine in the early 1980s (the first oral agent to selectively target T-lymphocyte pathways) led to a dramatic reduction in acute rejection rates and improved graft and patient survival. A combination of cyclosporine, azathioprine, and corticosteroids ("triple therapy") became the standard of care for pediatric and adult heart transplantation. The introduction of several new agents in the past decade has resulted in an almost infinite number of potential immunosuppressive regimens, none of which have been (or are likely to be) tested in randomized clinical trials in children. Tacrolimus is replacing cyclosporine as the primary calcineurin inhibitor in many programs. Mycophenolate mofetil, despite its increased cost, is likely to replace azathioprine as the adjunctive antimetabolite of choice in heart transplantation. Furthermore, target of rapamycin inhibitors, such as sirolimus, will likely be used in lieu of antimetabolite agents if their known myointimal antiproliferative effects are demonstrated to reduce or prevent graft vasculopathy (chronic rejection) in humans. With the availability of more potent immunosuppressive agents, early steroid withdrawal or complete steroid avoidance will become the standard of care in most pediatric transplant programs. Complete avoidance of steroids can be facilitated by the use of induction therapy with polyclonal anti-T-cell antibodies (eg, rabbit antithymocyte globulin ) or with the use of nondepleting antibodies that block the interleukin-2 receptor (eg, basiliximab, daclizumab). All these agents appear to have a good safety profile and are likely to lead to a resurgence of interest in induction therapy as a strategy to avoid chronic use of corticosteroids in children. As the elucidation of immunosuppressive pathways continues to advance, many newer immunosuppressive agents will be developed that target specific critical pathways in the immune response to the allograft. These advances should lead to more focused immunosuppression, greater drug synergism, reduction in the doses of individual agents, steroid-sparing regimens, and reduction in end-organ toxicities. The ultimate goal will be to define a perioperative therapeutic regimen that will result in a state of " transplantation tolerance," in which the patient will indefinitely accept their allograft without the need for chronic immunosuppressive therapy.

Influence of extracorporeal photopheresis on clinical and laboratory parameters in chronic graft-versus-host disease and analysis of predictors of response

We report 28 patients with advanced chronic graft-versus-host disease (cGVHD) treated with extracorporeal photopheresis (ECP). All had failed conventional immunosuppressive therapy. Of the patients, 27 had extensive cGVHD and 20 had more than 50% cutaneous surface area involvement. ECP was initiated approximately 2 years after onset of cGVHD and 3 years following allogeneic stem cell transplantation and administered fortnightly for 4 months and then monthly. Response was assessed using quantifiable disease measures, including skin score, liver function tests (LFTs), blood counts, and lung function tests. Regression analysis allowed assessment of any pretreatment clinical or laboratory parameters that predicted response. There were 25 patients who completed 3 months and 21 who completed 6 months of treatment. Systemic immunosuppression was stable or reduced in 86% of patients. There were 3 patients who died from cGVHD. After 6 months, median skin scores were 53% lower (P =.003) in sclerodermoid and lichenoid disease. Of 6 patients with mucosal ulceration, 3 improved. A nonsignificant improvement of LFTs occurred. We infer that ECP is effective even in patients with extensive cutaneous cGVHD of 2 years duration that is resistant to conventional therapy. Furthermore, both sclerodermoid and lichenoid subtypes responded. However, no baseline parameters predicted a favorable response to ECP, so patient selection must continue to be made on clinical grounds.

Mechanisms of action of extracorporeal photochemotherapy

Extracorporeal photochemotherapy (ECP) has been shown to be effective in variety of pathologic diseases such as Sezary syndrome, autoimmune diseases, organ graft rejection and graft versus host disease. However, its mechanism of action has remained elusive. Understanding of its mechanisms may be useful to identify the best indications, treatment regimes and to optimize the ECP technique. The first step of the ECP procedure is collection of peripheral mononuclear cells. In this step, several cell environment changes occur. These conditions have been suggested to increase monocyte activation and possibly drive dendritic cell differentiation. The second step of ECP is the cell radiation by UVA in presence of 8-MOP which is presumed to induce cell membrane damage, DNA crosslinking and binding to a variety of cytosolic proteins leading to apoptosis, modification of membrane antigenicity and antigen presenting cell activation. The third step of ECP is the reinfusion of the treated cells to the patient. While it is unclear what exactly occurs in vivo, it is thought that DCs play a critical role by inducing an immunological response against pathogenic cells. The immature DC, activated by ECP, phagocytizes and internalizes the apoptotic cells; processes the antigens and increases the synthesis of class I and II Major Histocompatibility Complex (MHC) molecules. The peptides associated with class II MHC are presented to the CD4+ T helper cells. The final maturation of DC is completed in vivo with the help of these activated T helper cells using a variety of mechanisms including CD40 ligation. Finally, the mature DCs fully loaded with pathogenic T cell peptides migrate to secondary lymphoid organs stimulate the naive CD8+ T cells and induce a cytotoxic response (Th1 immune response) directed against pathogenic clones (tumoral cells of Sezary syndrome). Clinical and haematological improvement after ECP in Sezary syndrome is associated with a shift in Th1/Th2 balance and the increase of Th1 cytokines and IL12. ECP can also down regulate the allo or autoimmune response and induces tolerance by regulatory T cells. The clinical response to ECP in patients with chronic GvHD is associated with increase in NK cells and a shift from DC1 to DC2 and a shift from predominantly Th1 to Th2 immune response. Recruitment and involvement of other immune cells in the mechanism of ECP have been suggested and merit more studies. This immunostimulatory capacity of ECP is the most probable hypothesis of its mechanism but further investigations are necessary to determine the precise players important for this activity.

Mononuclear cell collection in patients undergoing extra-corporeal photo-chemotherapy for acute and chronic graft-vs.-host-disease (GvHD): comparison between COBE Spectra version 4.7 and 6.0 (AutoPBSC)

A constant improvement in the performance of blood cell separators has been observed in recent years, allowing better yields in peripheral blood stem cell collection (PBSC) either from healthy donors or for autologous purposes. Nevertheless, to our knowledge, no reports on the efficiency of mononuclear cell (MNC) collection in patients undergoing extra-corporeal photochemotherapy (ECP) for graft-vs.-host-disease (GvHD) have been published. We retrospectively investigated the efficiency of 167 MNC collections performed consecutively in 12 patients between January 1999 and June 2001 by means of the COBE Spectra version 4.7 (V 4.7) or version 6.0 (V 6.0), for 109 and 58 procedures, respectively. MNC fractional extraction (FE) was higher in the V 6.0 group compared to the V 4.7 group : 0.59 +/- 0.21 vs. 0.51 +/- 0.22 (P < 0.05). However, platelet contamination was lower in the products obtained with V.6.0 compared to those obtained with V.4.7: 740 ( 630 x 10(3)/(L vs. 2,073 ( 1,429 x 10(3)/(L (P < 0.05). Only two patients with acute GvHD, both from V 4.7 group, required post-ECP platelet transfusion. The recently released version 6.0 allowed a satisfactory MNC yield with minimal platelet contamination in patients scheduled to undergo ECP for acute or chronic GvHD.

Extracorporeal photochemotherapy for paediatric patients with graft-versus-host disease after haematopoietic stem cell transplantation

This study aimed to ascertain whether extracorporeal photochemotherapy (ECP) is an effective treatment for paediatric patients with refractory graft-versus-host disease (GVHD). From January 1992 to December 2000, 77 children (median age 8.6 years) with either acute (n = 33) or chronic (n = 44) GVHD, resistant to conventional immunosuppressive therapy, were treated with ECP in four Italian paediatric hospitals. After ECP, acute GVHD involving skin, liver and gut responded completely in 76%, 60% and 75% of patients respectively. The 5-year overall survival was 69% for responding patients vs 12% for non-responders (P = 0.001). Among the 44 children with chronic GVHD, 15 (44%) showed a complete response and 10 (29%) a significant improvement after ECP. The 5-year overall survival was 96% for responders vs 58% for non-responders (P = 0.04). Our results suggest that ECP is an effective treatment that may be useful in paediatric patients with either acute or chronic GVHD who have failed to respond to standard immunosuppressive therapy.

The effect of exposing murine splenocytes to UVB light, psoralen plus UVA light, or gamma-irradiation on in vitro and in vivo immune responses

BACKGROUND

WBCs in blood components are a major factor contributing to immune responses such as GVHD and alloimmunization that follow transfusion. Irradiation of blood components has been used to regulate the contribution of donor WBCs to these immune responses. A systematic comparison of how the exposure of lymphoid cells to gamma-irradiation, UVB light, or psoralen + UVA light (PUVA) effects immune response was conducted to better define the best type of irradiation to be used in different clinical settings.

STUDY DESIGN AND METHODS

Murine spleen cells were irradiated with varying doses and tested for their in vitro ability to be activated, to proliferate in response to mitogen or allogeneic stimulator cells, or to serve as stimulator cells. Irradiated donor cells were also tested for in vivo generation of GVHD, induction of alloantibody production, induction of restricted cytolytic T lymphocytes, and persistence of irradiated cells.

RESULTS

In general, increasing amounts of irradiation resulted in increased inhibition of in vitro and in vivo responses, although the doses required for inhibition differed from assay to assay. In contrast, irradiation of donor cells did not always result in inhibition of recipient alloantibody responses but was dependent on the donor-recipient combination that was studied.

CONCLUSION

Control of the in vivo outcomes of transfusing allogeneic cells is regulated by the type and dose of irradiation used and by the genotype of the donor and/or recipient.

Prevention and treatment of severe hemodynamic compromise in pediatric heart transplant patients

Allograft rejection is a leading cause of severe hemodynamic compromise in pediatric heart transplant patients. A triple-drug immunosuppression regimen, which includes a calcineurin inhibitor, antiproliferative agent, and corticosteroid, suppresses the immune system at multiple different levels for optimal graft protection while minimizing the adverse effects of any one particular agent. Some pediatric centers also use induction therapy with anti-T cell antibodies immediately following transplantation as additional rejection prophylaxis. These antibodies augment immunosuppression by either depleting the T cell pool or blocking interleukin-2 receptors on activated T cells. Despite the aggressive preventive measures outlined above, some pediatric heart transplant patients will develop severe hemodynamic compromise, most commonly due to fulminant rejection. Such patients require attention to, and optimization of, the four determinants of cardiac output (heart rate, preload, contractility and afterload) to stabilize the circulation until the rejection can be reversed. Careful administration of volume, diuretics, inotropes, and afterload-reducing agents will meet this goal. Patients with allograft rejection require augmentation of immune suppression to facilitate myocardial recovery. Corticosteroids form the cornerstone of treatment for both cellular and vascular rejection. In patients with refractory cellular rejection, conversion to mycophenolate mofetil or tacrolimus may be appropriate if these agents are not already being used for maintenance immunosuppression. Critically ill patients may additionally benefit from muromonab-CD3 (OKT3) to augment lympholysis. Treatment employed specifically for humoral rejection is prescribed with the intention of suppressing new antibody formation, removing circulating antibody, and improving coronary blood flow. In addition to corticosteroids, cyclophosphamide and antithymocyte globulin or muromonab-CD3, along with plasmapheresis, may improve survival. Systemic heparinization should be considered to minimize coronary thrombosis in patients with humoral rejection. In the future, novel immunosuppressive agents may further assist in the prevention as well as treatment of severe hemodynamic compromise due to rejection in pediatric heart transplant recipients.

An approach to evidence-based therapeutic apheresis

This review is derived from a memorial lecture honoring Dr. Francis Morrison, a former President of the American Society For Apheresis (ASFA). The author had numerous professional contacts with Dr. Morrison through ASFA in the early 1990s, having served with him on the Board of Directors and followed him as President, and also came to know him well on a personal level. Professionally, Dr. Morrison stood out as a courtly gentleman with a marvelous baritone voice whose ability to facilitate organization contributed to a growing sense of dignity and purpose in the affairs of the society. On the personal side, however, there wasn't an ounce of pretension in him. He was accessible and down-to-earth; a genuine character with an active and appealing sense of humor. Not surprisingly, he seemed to have a wealth of insight and "common sense," and since the topic of this study is a kind of common sense approach to assessing the effectiveness of therapeutic apheresis, it seems a fitting way to honor his memory.

Extracorporeal photopheresis in the treatment of persistent rejection in a pediatric lung transplant recipient

Lung transplantation is an accepted therapy for children with end-stage lung disease. One-year lung transplant survival rates of 86% have been reported by the United Network for Organ Sharing. Allograft rejection is a common cause of death following transplantation. Extracorporeal photopheresis is a novel therapy used to treat solid-organ rejection; this therapy involves separating the leukocyte-rich fraction from whole blood, treating with psoralen and ultraviolet light A exposure. The objective of therapy is to reverse progressive and persistent rejection. Working collaboratively with an institution that offers extracorporeal photopheresis may provide an alternative or additional therapy in the management of ongoing rejection following solid-organ transplantation.

Rapamycin as rescue therapy in a patient supported by biventricular assist device to heart transplantation with consecutive ongoing rejection

Rapamycin is a new immunosuppressive agent that has been shown to be effective in acute heart allograft rejection. This case documents a patient suffering from cardiac sarcoidosis who was bridged to transplantation for 90 days with ongoing rejection after allograft implantation. Rejection did not abate despite treatment with antithymocyte globulin (ATG), FK506, a mycophenolate switch and courses of multiple apheresis. Initiation of rapamycin treatment resulted in a rapid resolution of cardiac rejection and reduction of concomitant immunosuppressive agents with few side-effects. Most notably was the reduction of panel reactive antibodies within a few weeks after the rapamycin initiation. This case illustrates that the utilization of rapamycin ceased ongoing rejection in a patient with a clear hyperimmune state despite prior extensive utilization of a variety of immunosuppressive strategies after heart transplantation.

Sézary syndrome and seronegative polyarthritis: treatment with extracorporeal photochemotherapy

We describe a patient with therapy-resistant cutaneous T-cell lymphoma, Sézary syndrome variant, in association with concurrent polyarthritis and vitiligo, who was successfully treated with extracorporeal photochemotherapy (ECP). The combination of Sézary syndrome with seronegative rheumatoid arthritis is rare. In our patient the T-cell lymphoma was refractory to standard treatments that included psoralen-UVA, lymph node irradiation, and polychemotherapy. ECP has been shown to be effective in the treatment of selected cases of Sézary syndrome. There is a strong suggestion that ECP as a monotherapy can provide a significant benefit for other T-cell-mediated diseases including rheumatoid arthritis. In spite of a disease duration of 10 years, a very low CD8 cell count (2% of lymphocytes), a very high CD4 cell count (94%), and multiple unsuccessful chemotherapeutic trials before initiation of ECP, our patient achieved a long-lasting complete remission of both diseases with normalization of the CD4+ and CD8+ T-lymphocyte subsets. Concurrent developing vitiligo was unaffected by ECP.

Quality control for the validation of extracorporeal photopheresis process using the Vilbert-Lourmat UV-A irradiation's system

In agreement with good practices for therapeutic use of human cells, quality control has to be performed to valid the process of extracorporeal photopheresis (ECP) with the Vilbert-Lourmat system. Since no protocol exists, we evaluated a technique based on the measurement of the inhibition of mitogen (PHA, Con-A, OKT3)-induced proliferation, in 164 procedures from 16 patients. Whatever the pathology, we observed a high proliferation rate in most samples, and we obtained over 90% ECP-induced inhibition in as many as 94% of the cases. Since this approach proved to be relevant regarding our objective, a protocol for the ECP process validation is proposed.

Adhesion of MNC to extracellular matrix proteins following in vitro photochemotherapy

BACKGROUND

Photochemotherapy is a safe and effective treatment for patients with drug-resistant severe GvHD. The technique involves the exposure of MNC to psoralen and UVA light (PUVA). We have investigated the effect of in vitro PUVA on MNC adhesion to extracellular matrix (ECM) proteins.

METHODS

MNC were isolated from peripheral blood (PB) and umbilical cord blood (UCB), and treated with PUVA. After labeling by a chemiluminescent probe, MNC were plated on ECM proteins (collagen, fibronectin, vitronectin and laminin) and the number of adherent cells was measured.

RESULTS

Untreated MNC from both PB and UCB showed a similar adhesion to the substrates. As a consequence of exposure to PUVA, most of PB samples showed significantly enhanced adhesion to the ECM proteins; on the other hand, UCB-recovered MNC did not significantly modify their adhesion.

DISCUSSION

MNC adhesion to ECM components is mediated by integrins, a family of cell membrane receptors; the ligand-binding affinity of certain integrins may be modulated by different stimuli. PUVA treatment of PB-recovered MNC may induce the up-regulation of the ligand-binding affinity of the integrins involved in the adhesion to ECM proteins. The finding of unmodified UCB cell adhesion after PUVA, may be related to the functional immaturity of lymphocytes at birth.

Regional anticoagulation with acid citrate dextrose-A for extracorporeal photoimmunochemotherapy

BACKGROUND AND OBJECTIVES

During photopheresis, intravenous heparin is used to prevent clotting in the extracorporeal circuit. Regional citrate anticoagulation could lower the risks associated with heparin treatment.

MATERIALS AND METHODS

Four-hundred and six photophereses procedures that were anticoagulated by acid citrate dextrose-A (ACD-A) (of which 343 were performed in patients at risk for haemorrhage) were analysed together with 278 heparin-anticoagulated treatments.

RESULTS

Four-hundred and four of 406 citrate treatments were completed. Seven transient paresthesias (1.73%), five of which occurred in the first 50 treatments, were observed. Bleeding complications were noted during heparin anticoagulation (1.07%), but not during citrate anticoagulation. During photopheresis, haemoglobin values and platelet counts decreased by 11.4% and 14.6%, respectively (P < 0.0001). Twenty-four hours after treatment, haemoglobin values, and platelet and leucocyte counts were still lower than at baseline (P < 0.0001). The changes of haemoglobin, platelet and leucocyte values did not differ for citrate and heparin.

CONCLUSIONS

In patients with contraindications against heparin use, ACD-A citrate anticoagulation during photopheresis is a safe and efficient alternative. Photopheresis induces profound changes of the blood count, irrespective of the anticoagulation method.

Characteristics of photopheresis treatments for the management of rejection in heart and lung transplant recipients

Photopheresis has been used in the management of rejection of heart and/or lung transplants. Although its mechanism of action remains unknown, irradiated T-helper cell-induced immunosuppression is the main theory. Since transplant recipients are often lymphopenic and lymphocytes are the target cells in phototherapy, we performed this study to determine which factors affect the cellular yield to undergo irradiation. We reviewed the records of all photophereses performed in our institution between July 1998 and April 2000 using the UVAR (first generation) or XTS (second generation) instruments (Therakos, Exton, PA). Our data included patient's blood volume, absolute lymphocyte count and hematocrit, catheter type, flow rate of collection cycles and centrifuge bowl size, as well as volume, hematocrit, and lymphocyte count of the cell suspension. With a mixed model multivariate analysis we sought to determine which variables predicted the lymphocyte yield. A total of 406 procedures in 25 adult patients was analyzed. There was no significant difference between the lymphocyte yield among the procedures performed with the first- and the second-generation instruments. The patient's absolute lymphocyte count was the only parameter, which positively correlated with the total number of lymphocytes collected for irradiation (P < 0.0001). Indeed, based on the mixed model, the total number of lymphocytes for irradiation can be predicted from the pre-procedure lymphocyte count. Additional studies are necessary to correlate the number of treated cells with patient outcome.

Effects of extracorporeal photoimmunotherapy on soluble IL-2Ralpha, TNF-RI, and CD8 in patients with steroid-resistant acute graft-versus-host disease

Extracorporeal photoimmunotherapy (ECP) has been successfully used as adjunct treatment for steroid-resistant graft-versus-host disease (GvHD) after allogeneic stem cell transplantation. We serially investigated serum levels of soluble interleukin-2 receptor-alpha (sIL-2Ralpha), soluble tumor necrosis factor receptor I (sTNF-RI), and soluble CD8 (sCD8) in 19 patients with steroid-resistant acute GvHD before and after each ECP treatment. Highest levels of sIL-2Ralpha and sTNF-RI correlated with severe acute GvHD and infections. Despite an immediate sIL-2Ralpha and sTNF-RI decrease after each treatment cycle, a mean surge of sTNF-RI>sIL-2Ralpha during the first three ECP cycles was observed in infections. A delayed surge, i.e., after the third ECP cycle, of sIL-2Ralpha and elevated post-ECP sCD8 levels was observed in patients developing chronic GvHD. While levels of sIL-2Ralpha and sTNF-RI correlate with the severity of acute GvHD and infections during the early ECP treatment period, the recurring increase of post-ECP sCD8 possibly may serve as parameter for developing chronic GvHD.

Extracorporeal photochemotherapy for the treatment of graft-versus-host disease

Photopheresis (extracorporeal photochemotherapy, ECP) is a new type of photochemotherapy used for the treatment of oncological and autoimmune diseases. Additionally, recent reports indicate that this therapy is promising in both pediatric and adult patients who develop graft versus host disease (GVHD) resistant to conventional protocols after bone marrow transplantation (BMT). In this paper, we review 31 studies where ECP was used in the treatment of acute and chronic GVHD. A total of 76 (32% female) acute GVHD patients have been considered in 11 series. Fifty-nine patients presented with skin involvement; 47 had liver involvement, and 28 had gastrointestinal manifestations. Treatment duration ranged from 1 to 24 months. A regression of skin manifestations was observed in 83% of the patients with a complete response in 67%. A complete regression of liver and gut manifestations was reported in 38% and 54% of the patients, respectively. The overall patient survival was 53%. Of the 43 patients alive, 8 developed chronic GVHD manifestations. The immunosuppressive therapy was discontinued in 28% of cases and reduced in 46%. A total of 204 (45% female) chronic GVHD patients treated with ECP 1 to 110 months from transplantation have been considered in 20 series. One hundred twenty-eight patients presented with skin involvement, 84 with liver, 31 with lung, and 59 with oral manifestations. Treatment duration ranged from 3 to 40 months. A regression of skin manifestations was observed in 76% of patients with a complete response in 38%. An improvement of liver and lung involvement was reported in 48% and 39% of the patients, respectively. Of the 59 patients with oral manifestations, an improvement was obtained in 63% of cases. The overall patient survival was 79%. ECP is a nonaggressive treatment that may benefit patients with both acute and chronic GVHD who do not respond to standard immunosuppressive therapy.

P-glycoprotein targeting: a unique strategy to selectively eliminate immunoreactive T cells

T lymphocytes have been found to harbor P-glycoprotein (Pgp) and to demonstrate modulation of its ion channel transporter function according to the state of activation of T lymphocytes. We hypothesized that cytotoxic chemicals that are extruded by Pgp could be used to specifically eliminate immunoreactive T-cell populations. In this study, we evaluated the capacity of 4,5-dibromorhodamine methyl ester (TH9402), a photosensitizer structurally similar to rhodamine, a dye transported by Pgp, and which becomes highly cytotoxic on activation with visible light to selectively deplete alloreactive T lymphocytes. Stimulation of T cells with mitogens or allogeneic major histocompatibility complex-mismatched cells resulted in the preferential retention of the TH9402 rhodamine-derivative in activated T cells, both CD4+ and CD8+. Photodynamic cell therapy of TH9402-exposed T cells led to the selective elimination of immunoreactive T-cell populations. In addition, this treatment preserved resting T cells and their capacity to respond to third-party cells. Inhibition of Pgp enhanced cellular trapping of the dye in nonactivated T cells and resulted in their depletion after exposure to light. Targeting of Pgp-deficient cells may therefore represent an appealing strategy for the prevention and treatment of graft-versus-host disease and other alloimmune or autoimmune disorders.

Psoralen and UVA light: an in vitro investigation of multiple immunological mechanisms underlying the immunosuppression induction in allograft rejection

Photopheresis (ECP) is a novel immunomodulatory therapy effectively used to treat several T-cell-mediated diseases and to reverse allograft rejection after organ transplantation. It consists of infusion of UVA-irradiated autologous leukocytes collected by apheresis and extracorporeally incubated with 8-methoxypsoralen (8-MOP). In this study we explored the potential immunological events for therapeutic efficacy of photopheresis in preventing allograft rejection by evaluating in vitro the combined effects of 8-MOP and UVA (PUVA) on multiple immunological parameters, such as induction of apoptosis, production of soluble mediators, and expression of cell antigens. Peripheral blood mononuclear cells (PBMCs) obtained from healthy subjects were treated with 8-MOP and UVA at the same doses as those clinically used in ECP. We demonstrate that PUVA treatment induced leukocyte hyporesponsiveness and a decrease in expression of co-stimulatory and adhesion molecules as well as of cytokine levels. Additionally, PUVA treatment induced apoptosis in both mononuclear cells (possibly through the Fas/FasL system and/or the CD38 pathway) and purified monocytes. In conclusion, our work focuses attention on the initial phase of immune response and identifies some new targets of therapy (e.g., costimulatory molecules) able to trigger final effects underlying therapeutic efficacy of photopheresis.

Drug treatment of clinical problems related to cardiac transplantation

In recent years, several new immunosuppressive agents have become available for the treatment of cardiac transplant recipients. Use of these agents and their potential side effects are reviewed.

Extracorporeal photochemotherapy: a new therapeutic approach for allograft rejection

Photopheresis (ECP) is a new immunomodulatory therapy in which recipient lymphocytes are treated extracorporeally with 8-methoxypsoralen (8-MOP) and ultraviolet light. The treatment seems to induce an inhibition of both umoral and cellular rejections after transplantation. More than 160 transplanted patients have been treated with ECP (107 heart, 30 kidney, 24 lung and I liver) in different studies. Indication for ECP included acute rejection, recurrent/refractory rejection, prophilaxis of rejection, need of reducing standard immunosuppression. Patient survival is satisfactory. Only one study where ECP was used as the last therapeutic resource in very compromised patients shows a high rate of mortality. On the contrary, when ECP was used earlier after the failure of a first immunosuppressive line the outcome was better with a very low mortality. An hystological resolution of acute rejection is reported in 89% of cardiac transplant patients. The rate of response is similar even in the other transplanted patients treated with ECP. A better control of alloreactivity has been also reported in both cardiac and renal transplant patients with recurrent rejection. In renal allograft the treatment induces a reduction of both lymphocytes and monocytes infiltrate and downregulates the expression of HLA-DR and integrins ICAM-1 and VCAM-1 on tubular cells. Markers of fibrogenesis such as TGFbeta1 and ASMA are only moderately reduced with a more focal pattern of distribution in the post-ECP specimens. The optimal schedule and the length of treatment are still unclear and probably a patient-tailored treatment is needed at least in responder patients. ECP is effective for patients resistant to conventional treatments, particularly when it is started early. This beneficial effect is obtained without the complications typically encountered with immunosuppressive regimens used to control rejection.

Transimmunization and the evolution of extracorporeal photochemotherapy

We are now aware that extracorporeal photopheresis (ECP) - in which a patient's leukocytes are isolated, passed through an ultrathin clear plastic plate, and exposed to 8-methoxypsoralen (8-MOP) and ultraviolet A light prior to reinfusion - is a simple and efficient dendritic cell (DC) therapy and the first FDA approved selective immunotherapy for cancer. DCs, as the most effective antigen presenting cells (APCs), are central to many ongoing efforts to stimulate immune responses to cancer cells. Moreover, ECP has not only demonstrated efficacy in the treatment of a T cell malignancy--namely cutaneous T-cell lymphoma (CTCL)--but also in treatment of oligoclonal T-cell-mediated diseases such as graft-versus-host-disease (GVHD) and organ transplant rejection. Recent advances in the understanding of DC/T-cell interactions provide insight into how ECP-induced DCs (EI-DCs) can be utilized to stimulate specific T-cell (i.e. anti-tumor) responses, or down-regulate a pre-existing potent T-cell response. The mechanism of this apparent paradox of EI-DC functionality is likely dependent on several fundamental principles: (1) the status of existing in vivo T-cell reactions, (2) the temporal stage of EI-DC differentiation, and (3) the affinity of the available repertoire of T-cell receptors (TCRs) for the antigen(s) in question. Further investigation into DC/T-cell interactions will help to shape the future of ECP and the ability to optimize this therapy for the desired immune effect. To this end, we are developing and testing Transimmunization to replace conventional ECP.

Transimmunization, a novel approach for tumor immunotherapy

This review describes our experience with the development of a novel form of immunotherapy that may represent the first practical and effective means of performing tumor-loaded dendritic cell (DC) immunotherapy. We have modified the highly successful extracorporeal photopheresis (ECP) treatment that has been used in the therapy of cutaneous T cell lymphoma (CTCL). autoimmune disease, transplantation rejection episodes and graft-versus-host disease to enhance its efficacy by the addition of an overnight incubation period. This adaption of ECP is termed "transimmunization (TI)" since the new therapy permits transfer of tumor antigens that have been previously poorly recognized to potent antigen presenting cells where the tumor epitopes can be displayed in the full context of major histocompatibility, co-stimulatory and adhesion molecules. The TI modification of ECP is a practical and safe means of rapidly inducing DC differentiation from peripheral blood monocytes in the presence of apoptotic tumor cells. Uptake of the apoptotic CTCL cells by the immature DC, in the presence of inflammatory cytokines, further drives their maturation into potent antigen presenting cells. Reinfusion of these tumor-loaded DC, that have access to the full spectrum of tumor antigens, has the potential to invoke an anti-tumor immune response in the recipient. Standard ECP has been a very useful form of immunotherapy and a modification of this approach that can enhance its ellicacy and utility should broaden its application to a larger variety of disorders including potentially the treatment of solid tumors and the modulation of the immune response in graft-versus-leukemia and graft-versus-host transplantation regimens. An understanding of the mechanism of ECP and TI will provide the physician with the ability to more finely tune the desired immune response and thereby, provide an enhanced immunotherapy for malignancy and other disorders of immunocompetence.

Extracorporeal photopheresis in chronic graft-versus-host disease

Despite significant advances in stem cell manipulation and post-transplant immunosuppression, chronic graft-versus-host disease (cGVHD) remains a cause of major long-term morbidity in survivors of allogeneic stem cell transplantation. Extracorporeal photopheresis (ECP) is a novel therapeutic intervention which has demonstrated efficacy in patients with refractory acute and chronic GVHD. Clinical responses have been reported in skin and visceral GVHD. While the long-term immunomodulatory effects of ECP in cGVHD are unknown, recent studies of patients undergoing a 6- to 12-month course of ECP treatment demonstrated an attenuation of Th1-mediated cytokine secretion by activated T-helper cells, a shift in the DC1/DC2 ratio favoring plasmacytoid rather than monocytoid dendritic cell profiles, and a decrease in antigen responsiveness by dendritic cells. The implications of these immunomodulatory effects of ECP on pathogenesis and clinical outcome remains a fertile area for future research.

Efficient tumor antigen loading of dendritic antigen presenting cells by transimmunization

Extracorporeal photochemotherapy (ECP), or photopheresis, was originally introduced for the management of patients with cutaneous T cell lymphoma (CTCL). Today, ECP remains the only FDA approved tumor-targeting selective immunotherapy for the treatment of any cancer. The key cellular events permitting ECP-induced anti-tumor immunity against CTCL are the induction of apoptotis in the malignant T cells, and the induction of monocyte-to-dendritic cell (DC) differentiation. In standard ECP, leukocytes extracorporeally exposed to psoralen and ultraviolet A light (UVA) are circulated back to the patient. However, recent findings suggest that co-incubation of these cells prior to re-infusion allows for more efficient phagocytosis and processing of the apoptotic malignant T cells by the newly formed DCs. Moreover, such a co-incubation step permits the direct external manipulation of this system and the design of strategies to augment the production of tumor-loaded DCs. These considerations have led to the development of Transimmunization, so named because it causes transfer of tumor antigens to newly formed dendritic cells capable of initiating immunization against the tumor cells, as the replacement technology for ECP. We will review the scientific understanding of ECP and explain how this can lead a more efficient, potentially broadly applicable, immunotherapy for cancer.

Successful reversal of severe refractory cardiac allograft rejection by photopheresis

We treated 4 patients with refractory International Society of Heart and Lung Transplantation Grades IIIA to IV cardiac allograft rejection with extracorporeal photopheresis. Following treatment on 2 consecutive days, 3 patients demonstrated complete histologic reversal of rejection. The remaining patient improved more gradually, but manifested complete cessation of rejection following three 2-day treatments. We conclude that photopheresis is a safe and effective modality for the treatment of severe refractory cardiac allograft rejection and that these results support the use of photopheresis in this clinical setting.

Apoptosis: the quiet death silences the immune system

Apoptosis plays an essential role in maintaining cellular homeostasis during development, differentiation, and pathophysiological processes. In the immune system, recent investigations reveal that during the course of T-cell development in the thymus, negative selection of autoreactive immature T-cells is a typical apoptotic process. In addition, apoptosis is also involved in cytotoxic killing of target cells and the regulation of lymphocyte homeostasis during immune responses. Interestingly, recent evidence has suggested that cells dying by apoptosis are actively involved in immunosuppression in various circumstances. We have shown that apoptotic cells could inhibit the expression of CD69 during T-cell activation. Furthermore, apoptotic cells phagocytosed by macrophages and/or dendritic cells are immunosuppressive, a process likely mediated by the production of transforming growth factor-beta1. Since apoptosis is a common mechanism by which excessive cells in many tissues and organs are eliminated in various pathophysiological processes, we believe that further investigation into the mechanisms by which apoptotic cells affect the immune system will not only lead to a better understanding of the significance of apoptosis during immune responses, but will also provide novel strategies for the management of autoimmune diseases and transplantation.

Extracorporeal photochemotherapy for treatment of acute and chronic GVHD in childhood

BACKGROUND

Extracorporeal photochemotherapy (EPC) has recently been proposed for the treatment of adults with either acute or chronic GVHD. However, data on children given this therapy are scarce. A Phase I-II study was carried out on EPC in children experiencing GVHD after allogeneic transplantation of HPCs.

STUDY DESIGN AND METHODS

Nine patients with steroid-resistant, grade II-IV acute GVHD and 14 with chronic GVHD, all of whom had been refractory to at least one line of treatment, were enrolled in this study and analyzed. The median age was 10.3 years (range, 5.4-18.1), and the median body weight was 35 kg (range, 17-89).

RESULTS

Seven of the nine patients with acute GVHD showed a response to EPC, whereas the disease progressed in the remaining two children (both with skin, gastrointestinal, and liver GVHD), and they died of grade IV acute GVHD. Among the seven children who responded to EPC, it was possible to completely discontinue immunosuppressive treatment in three. In the 14 children with chronic GVHD, 4 and 5 patients experienced complete and partial response to EPC, respectively, whereas the remaining 5 patients, all with extensive chronic GVHD, had stable disease or disease that progressed during EPC. Among these latter 5 patients, 3 died. In 6 of the 9 patients with chronic GVHD responding to EPC, immunosuppressive therapy was discontinued.

CONCLUSION

EPC is safe, feasible, and effective in children with either acute or chronic GVHD occurring after an allograft.

Feasibility of photopheresis to reduce the occurrence of restenosis after percutaneous transluminal coronary angioplasty: a clinical pilot study

BACKGROUND

Photopheresis was evaluated as a means of preventing restenosis on the basis of immune modulation.

METHODS

This was a prospective, randomized, controlled clinical trial analyzing clinical restenosis at 6 months after percutaneous transluminal coronary angioplasty (PTCA). Seventy-eight patients with single-vessel angioplasty were randomly assigned to a control group of 41 patients and a treatment group of 37 patients. At 6 months, there were 72 evaluable patients: 39 control patients and 33 treated. Twenty-nine control patients received balloon PTCA only and 10 patients received stents. Twenty treated patients received PTCA only and 13 patients received stents. Baseline clinical characteristics of both groups were similar. The treatment group received photopheresis for a total of 5 treatments. Primary end points were death from any cause, myocardial infarction, ischemia, and repeat revascularization procedures.

RESULTS

By intention-to-treat analysis, clinical restenosis occurred in 27% of control patients versus 8% of treated patients (P =.040, relative risk = 0.30).

CONCLUSIONS

Photopheresis therapy in patients undergoing balloon PTCA with and without stent deployment has been shown to be effective in reducing restenosis. The use of photopheresis in such patients merits further investigation.