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

The challenge of rejection and cardiac allograft vasculopathy

Since the first human heart transplantation was performed in 1967, the field of heart transplantation has advanced to the point where survival and acceptable quality of life are commonplace. Despite remarkable progress in the clinical management of rejection, rejection continues to limit survival and quality of life in the heart transplant population. This review will discuss the biologic processes involved in hyperacute rejection, acute rejection, and humoral (vascular) rejection. The development of endomyocardial biopsy techniques represented a significant advancement in the diagnosis of cardiac rejection, and endomyocardial biopsy remains the 'gold standard' in the diagnosis of cellular rejection. To date, no noninvasive parameters will diagnose rejection with adequate sensitivity and specificity. Biopsy frequency and immunosuppressive therapies may be tailored to the risk of rejection. Immunosuppression for cardiac transplantation can be divided into three major phases: 1) perioperative immunosuppression; 2) maintenance immunosuppression, and; 3) treatment of rejection. The strategy for treating transplant rejection should be influenced by several variables: 1) Histologic grade of rejection; 2) Evidence of hemodynamic compromise by ejection fraction or right heart catheterization; 3) Severity of previous rejection episodes and types of immunosuppressives used; and 4) Risk factors for rejection, including time after transplantation. Future rejection therapy will involve more sophisticated attempts to alter host responses toward the donor organ in a more specific and selective way. Despite considerable advances in the care of the heart transplant recipient, long-term survival is limited by cardiac allograft vasculopathy. The final section of this chapter will review the pathology, immunopathology, nonimmunologic risk factors, diagnosis, prevention and treatment of allograft vasculopathy.

Extracorporeal photochemotherapy in patients with steroid-dependent Crohn's disease: a prospective pilot study

BACKGROUND

Extracorporeal photochemotherapy has been proven effective in selected T-cell mediated diseases.

AIM

To evaluate the safety and efficacy of extracorporeal photochemotherapy in patients with steroid-dependent Crohn's disease by an open, monocentric trial in three phases of 24 weeks each.

METHODS

In phase 1 standardized steroid tapering was initiated in patients with a history of steroid-dependent Crohn's disease. Those with a prospectively evaluated maintenance dose of at least 10 mg/day prednisolone continued steroid-withdrawal under the application of extracorporeal photochemotherapy in phase 2. The duration of remission or response was followed during phase 3. Colonic tissue bioptically obtained before and after extracorporeal photochemotherapy was studied by immunofluorescence microscopy for the presence of photoadduct positive cells.

RESULTS

Out of 24 patients included in phase 1, 10 entered phase 2 for extracorporeal photochemotherapy. Four subjects achieved remission and four others response. Significant reductions in serum C-reactive protein levels and intestinal permeability were measured, as well as increases in quality of life and plasma adrenocorticotropic hormone levels. No major side-effects were observed. Remission remained stable in three out of four patients during phase 3. In three patients, positive nuclear stainings of photoadducts were detected in colonic mononuclear cells after extracorporeal photochemotherapy.

CONCLUSIONS

Extracorporeal photochemotherapy represents a safe steroid-sparing approach in patients with Crohn's disease and is associated with intestinal homing of photopheresed cells.

Photopheresis at onset of type 1 diabetes: a randomised, double blind, placebo controlled trial

BACKGROUND

In recent years photopheresis, an extracorporeal form of photochemotherapy using psoralen and ultraviolet A irradiation of leucocytes, has been claimed to be an effective form of immunomodulation.

AIM

To evaluate its effect in type 1 diabetes we performed a double blind, controlled study using placebo tablets and sham pheresis in the control group.

METHODS

A total of 49 children, aged 10-18 years of age at diagnosis of type 1 diabetes were included; 40 fulfilled the study and were followed for three years (19 received active treatment with photopheresis and 21 placebo treatment).

RESULTS

The actively treated children secreted significantly more C peptide in urine during follow up than control children. C peptide values in serum showed corresponding differences between the two groups. The insulin dose/kg body weight needed to achieve satisfactory HbA1c values was always lower in the photopheresis group; there was no difference between the groups regarding HbA1c values during follow up. The treatment was well accepted except for nausea (n = 3) and urticaria (n = 1) in the actively treated group. There were no differences regarding weight or height, or episodes of infection between the two groups during follow up.

CONCLUSION

Photopheresis does have an effect in addition to its possible placebo effect, shown as a weak but significant effect on the disease process at the onset of type 1 diabetes, an effect still noted after three years of follow up.

Extracorporeal photopheresis: a review

Extracorporeal phototherapy (ECP) is a therapeutic approach based on the biological effect of psoralen 8-methoxypsoralen (8-MOP) and ultraviolet light A (UVA) on mononuclear cells collected by apheresis, and reinfused into the patient. Photopheresis is widely used for the treatment of patients with advanced cutaneous T-cell lymphoma (CTLC). Evidence suggests that it prolongs life, and also induces 50-75% response rates. In addition, more and more reports indicate that photopheresis is a potent agent in the therapy of acute allograft rejection among cardiac, lung and renal transplant recipients. There are increasing amounts of data showing that patients with chronic graft versus host disease benefit from this therapy. Likewise, there are indications that there may be a potential role for ECP in the therapy of certain autoimmune diseases resistant to conventional therapy. The mechanism of this treatment is likely due to the induction of anticlonotypic immunity directed against pathogenic clones of T lymphocytes. Treatment induces apoptotic death of pathogenic T-cells, and it is postulated that activation of antigen-presenting cells has important effects in this process.

Induction of human tumor-loaded dendritic cells

A preferred anti-cancer vaccine would be tumor-specific, simple to rapidly construct and safe to administer. It would permit immunization against a spectrum of the tumor's distinctive antigens, without requiring their prior identification. Toward these goals, we describe a modification of standard extracorporeal photopheresis (ECP) which initiates, within a single day, both monocyte-to-dendritic cell (DC) differentiation and malignant cell apoptosis. The transition of monocytes to immature DCs was identified by the expression of cytoplasmic CD83 and membrane CD36 in the absence of membrane CD14 staining, as well as induction of membrane CD83 expression. Differentiating DCs were avidly phagocytic and engulfed apoptotic malignant T cells. Differentiating DCs were capable of stimulating significant proliferation of normal alloreactive lymphocyte responders, indicting increased expression of membrane MHC class II molecules. This approach provides a clinically practical means of developing tumor-loaded cells that have initiated the transition to DCs without the requirement of exogenous cytokines, excessive cellular manipulation or isolation. Construction of DC vaccines using this methodology can be generalized to other diseases and may offer a novel approach for improved cancer immunotherapy.

Transplant Coronary Vasculopathy

Because the transplanted heart is denervated, classic angina as a symptom of allograft coronary vasculopathy rarely is perceived. Any cardiac transplant patients who presents with decreased exercise capacity, shortness of breath, or syncope should be assessed thoroughly. Unfortunately, the initial presenting symptom of transplant vasculopathy may be acute myocardial infarction, heart failure, or even sudden death. Patients should be evaluated on an annual basis for the presence of transplant coronary vasculopathy in addition to when clinical suspicion warrants. Coronary angiography has been the main modality of invasive assessment, although it is insensitive. Recently, intracoronary ultrasound has been used in conjunction with angiography to detect the first evidence of transplant vasculopathy, manifested as thickening of the intimal layer of the vessel wall due to smooth muscle cell proliferation, which ultimately leads to luminal narrowing. Patients with evidence of vasculopathy should undergo functional evaluation with dobutamine echocardiography to document ischemic burden. Preventive measures include traditional coronary risk factor modification. Patients are started on statins early in the post-transplantation period and hypertension is treated aggressively using calcium channel blockers and angiotensin-converting enzyme (ACE) inhibitors. Because of their deleterious metabolic effects, steroids may be withdrawn under close surveillance for rejection. After transplant vasculopathy has developed, it is difficult to treat and options are limited. Patients with discrete luminal obstructions may undergo angioplasty, stenting, or coronary artery bypass. However, these procedures are palliative, and the only definitive therapy is retransplantation.

New immunosuppressive drugs in heart transplantation

Only a few randomized clinical trials have been performed so far in heart transplant recipients, mainly because of the relatively small number of heart transplants performed worldwide each year. The main focus of the few controlled trials that have been completed has been the prevention and treatment of heart allograft rejection. In the area of pharmacologic immunosuppression, both biological agents and drugs have been the subject of investigation. Among the biological agents, chimeric monoclonal antibodies directed against the interleukin (IL)-2 receptor, which have been found to be safe and effective in renal transplant recipients, are now undergoing the test of controlled trials in heart transplant recipients. Immunosuppressive drugs that have been studied in controlled trials include calcineurin inhibitors (such as the microemulsion formulation of cyclosporine and tacrolimus) and inhibitors of purine synthesis, such as mycophenolate mofetil. Non-pharmacologic prophylactic immunosuppression with photopheresis has also been tested in a prospective, multicenter, randomized trial. New immunosuppressive regimens, such as mycophenolate mofetil combined with a monoclonal antibody against the IL-2 receptor, are being tested with the aim to reduce or eliminate calcineurin inhibitors or corticosteroids. Although clinical approaches to the induction of tolerance have undergone preliminary clinical evaluation, the ability to induce tolerance to an allograft in humans remains an elusive goal.

The treatment of cutaneous T-cell lymphoma with a novel retinoid

The clinical experience with bexarotene for cutaneous T-cell lymphoma (CTCL) at our center is reviewed here. Disease activity assessment was monitored every 4 weeks in all patients. Five target lesions were monitored, an area score was performed, and a CTCL-specific health assessment questionnaire was administered. Four patients with refractory plaque CTCL were treated with bexarotene gel. All target lesions disappeared after 8 weeks of therapy, with recurrences observed in untreated areas. In the follow-up period, no recurrences of the original target lesions were observed. One patient withdrew from the study. Patients with refractory patch/plaque disease were randomized to a high-dose (300 mg/m(2)) or low-dose (6.5 mg/m(2)) daily oral regimen of bexarotene. After showing disease progression, the two patients on the low-dose arm were entered into the high-dose arm after 8 weeks. Marked clinical responses were seen in all patients treated. The target lesions showed either complete disappearance or a reduction in lesion size, duration, and scale. No new lesions were noted in patients on high-dose bexarotene. Self-assessments also confirmed the palliative properties of the observed responses. All patients had hypertriglyceridemia despite the concomitant administration of atorvastatin at 60 mg/day. Dose reductions were required to maintain safe lipid levels. Four patients with erythrodermic CTCL were treated with high-dose oral therapy, and all patients showed rapid (within 2 weeks) improvement of erythroderma and symptoms.

Extracorporeal photochemotherapy in the treatment of severe steroid-refractory acute graft-versus-host disease: a pilot study

Extracorporeal exposure of peripheral blood mononuclear cells to the photosensitizing agent 8-methoxypsoralen and UV-A radiation has been shown to be effective in the treatment of selected diseases mediated by T cells, rejection after solid organ transplantation, and chronic graft-versus-host disease (GVHD). We present 21 patients with a median age of 38 years who developed steroid-refractory acute GVHD grades II to IV after stem cell grafting from sibling or unrelated donors and were referred to extracorporeal photochemotherapy (ECP). Three months after initiation of ECP 60% of patients achieved a complete resolution of GVHD manifestations. Complete responses were obtained in 100% of patients with grade II, 67% of patients with grade III, and 12% of patients with grade IV acute GVHD. Three months after start of ECP complete responses were achieved in 60% of patients with cutaneous, 67% with liver, and none with gut involvement. Adverse events observed during ECP included a decrease in peripheral blood cell counts in the early phase after stem cell transplantation (SCT). Currently, 57% of patients are alive at a median observation time of 25 months after SCT. Probability of survival at 4 years after SCT is 91% in patients with complete response to ECP compared to 11% in patients not responding completely. Our findings suggest that ECP is an effective adjunct therapy for acute steroid-refractory GVHD with cutaneous and liver involvement. However, in patients with acute GVHD grade IV or gut involvement other therapeutic options are warranted.

Extracorporeal photochemotherapy in the treatment of severe steroid-refractory acute graft-versus-host disease: a pilot study

Extracorporeal exposure of peripheral blood mononuclear cells to the photosensitizing agent 8-methoxypsoralen and UV-A radiation has been shown to be effective in the treatment of selected diseases mediated by T cells, rejection after solid organ transplantation, and chronic graft-versus-host disease (GVHD). We present 21 patients with a median age of 38 years who developed steroid-refractory acute GVHD grades II to IV after stem cell grafting from sibling or unrelated donors and were referred to extracorporeal photochemotherapy (ECP). Three months after initiation of ECP 60% of patients achieved a complete resolution of GVHD manifestations. Complete responses were obtained in 100% of patients with grade II, 67% of patients with grade III, and 12% of patients with grade IV acute GVHD. Three months after start of ECP complete responses were achieved in 60% of patients with cutaneous, 67% with liver, and none with gut involvement. Adverse events observed during ECP included a decrease in peripheral blood cell counts in the early phase after stem cell transplantation (SCT). Currently, 57% of patients are alive at a median observation time of 25 months after SCT. Probability of survival at 4 years after SCT is 91% in patients with complete response to ECP compared to 11% in patients not responding completely. Our findings suggest that ECP is an effective adjunct therapy for acute steroid-refractory GVHD with cutaneous and liver involvement. However, in patients with acute GVHD grade IV or gut involvement other therapeutic options are warranted.

Sézary syndrome: diagnostic criteria and therapeutic options

Sézary syndrome (SS) is a rare form of erythrodermic cutaneous T-cell lymphoma with hematological involvement and a poor prognosis. Therapies include photopheresis, with or without interferon, chemotherapy, and total skin electron beam therapy. The lack of any randomized studies makes it difficult to assess the effect of current therapy on survival. In addition, the different response rates reported for individual treatments may depend as much on the criteria used to define SS as the therapy itself. This article reviews the diagnostic tests that are needed to reliably diagnose SS and offers a critical analysis of current treatment options.

Immunologic Aspects of Transplant Management: Pharmacotherapy and Rejection

The intensivist caring for the critically ill transplant patient must be knowledgeable in the management of immunosuppression or have expert help. Critical illness often has a major impact on the absorption and metabolism of immunosuppressive drugs, increasing or decreasing net immunosuppression. Too little immunosuppression brings the risk of graft loss, while too much increases the morbidity and mortality of serious infection. Optimum management often requires the skillful manipulation of dosage and/or routes of drug delivery. In many cases of life-threatening infection, immunosuppression must be discontinued altogether and restarted prior to significant graft injury. The cost of miscalculation is very high. Loss of a renal, pancreas, or small bowel transplant is tragic, while loss of a heart, lung, or liver is usually fatal. Unfortunately the management of immunosuppression is becoming more complex. As the field of transplantation matures, new immunosuppressants are being introduced. Also, more experience and growing numbers of clinical trials are making the required knowledge base ever larger. Each type of transplant has its own set of evolving immunosuppression strategies. This review presents the basic mechanisms of the most widely used drugs and the dangers of immunosuppression. The drugs are then discussed in the context of liver, small bowel, kidney, pancreas, heart, and lung transplantation. Finally, a brief section on the practical pharmacokinetics of the drugs is presented.

Prophylactic photopheresis and chronic rejection: effects on graft intimal hyperplasia in cardiac transplantation

BACKGROUND

Despite the decreased incidence of acute rejection episodes and improvements in short and intermediate term graft survival with current immunosuppressive agents, there has been little progress in decreasing the morbidity and mortality from chronic rejection. This phenomenon may, in part, be related to the development of a humoral immune response with increases in anti-HLA antibodies, which presents as accelerated graft arteriopathy with intimal hyperplasia.

METHODS

Based on prior experimental work, a pilot, prospective, randomized study was performed in 23 primary cardiac transplant recipients to determine whether the addition of prophylactic photopheresis to a cyclosporine, azathioprine and prednisone regimen was safe and resulted in decreased levels of panel reactive antibodies (PRA) and transplant arteriopathy.

RESULTS

There was no difference between the two groups in regard to infection or acute rejection incidence. The photopheresis group had a significant reduction in PRA levels at two time points within the first 6 postoperative months. Coronary artery intimal thickness was significantly reduced in the photopheresis group at 1-yr (0.23 vs. 0.49 mm, p < 0.04) and 2-yr (0.28 vs. 0.46 mm, p < 0.02) follow-up compared with the control group.

CONCLUSION

In this small pilot study, photopheresis is a safe, well-tolerated immunomodulatory technique that is capable of decreasing the severity of chronic rejection manifesting as post-transplant graft intimal hyperplasia.

Immunosuppressive therapies after heart transplantation: best, better, and beyond

Despite the significant advances in transplantation immunology and immunosuppressive therapies over the past 30 years, current immunosuppressive regimens are still inadequate in the majority of cardiac transplant recipients. Although short- and long-term survival rates have improved significantly, only 50% will survive 10 years and very few will survive 20 years. Complications of overimmunosuppression and underimmunosuppression account for the majority of these deaths. Only true "immunologic" tolerance can provide the outcome we pursue, namely, prolonged allograft function and otherwise normal immune function without chronic immunosuppressive therapy and its risks. Until a successful tolerance-inducing protocol is developed, we must use the current and upcoming immunosuppressive agents and techniques.

Apoptotic cells actively inhibit the expression of CD69 on Con A activated T lymphocytes

Although apoptosis is commonly viewed as a silent cell death without damage to adjacent tissues, the effect of apoptosis on immunity has been unclear. We have investigated the influence of apoptotic cells on T-cell activation. The K562 or HL-60 human leukemia cell lines that had been induced apoptosis by FTY720 or cycloheximide (CHX) were added into the culture of mouse spleen cells stimulated with Con A. Six to 20 h later, the expression of CD69, an early T-cell activation antigen, was detected using flowcytometry. Living cells and necrotic cells served as control groups. Apoptotic K562 or HL-60 cells induced by either FTY720 or CHX unanimously inhibited CD69 expression on the CD3+ mouse T cells while living and necrotic cells did not. The inhibition was proportional to the number of apoptotic cells and was different in the T-cell subsets, showing a rapid and transient inhibition on the CD3+CD8+ T-cell activation but with a slow and continuous inhibition on CD3+CD8- T-cell activation. In conclusion, the apoptotic cells actively inhibit a T-cell activation that is independent of the cell lines or the apoptotic inducers, indicating that the apoptotic cells dominantly regulate T-cell immunity.

Photopheresis and autoimmune diseases

Although several case reports and case series suggest efficacy for photopheresis in the treatment of autoimmune diseases, few controlled studies have been conducted to test this hypothesis. After a decade of interest, multiple case reports, open trials, and one controlled study, the role of photopheresis in autoimmune disease remains to be established. Controlled multi-center trials in rheumatoid arthritis, SLE, and scleroderma may be costly but are clearly necessary for proper evaluation of this therapy.

Extracorporeal photochemotherapy in the treatment of severe graft-versus-host disease

Advances in posttransplant immunosuppression have to the present not been able to prevent the development of graft-versus-host disease (GVHD) in patients given related or unrelated stem cell grafts for cure of hematologic diseases. Patients with GVHD not responding to first line therapy with corticosteroids remain at high risk of death due to severe infections or organ failure. Extracorporeal exposure of peripheral blood mononuclear cells to the photosensitizing agent 8-methoxypsoralen and ultraviolet A radiation has been shown to be effective in treatment of selected T-cell mediated diseases, including cutaneous T-cell lymphoma and rejection after organ transplantation. Extracorporeal photochemotherapy (ECP) is also a safe and efficacious adjunct therapy for both acute and chronic extensive GVHD with skin and visceral involvement and resistance to conventional immunosuppressive therapy. A multicenter randomized study should help define the impact of ECP in the treatment of GVHD and overall survival of these patients.

Management of graft-versus-host disease in paediatric bone marrow transplant recipients

We discuss clinical strategies for the prophylaxis and treatment of both acute and chronic graft-versus-host disease (GVHD) with particular attention to children. Grades II to IV acute GVHD occur in 10 to 50% of patients given an allogeneic transplantation of haemopoietic stem cells (HSCT) from a genotypically HLA-identical donor. A significantly higher incidence and severity of the disease is reported in patients receiving transplants from partially matched family donors or unrelated volunteers. Younger individuals or patients receiving HSCT from younger donors develop GVHD less frequently than do older recipients. Severe acute GVHD is characterised by a significant decrease in survival probability, even though the graft-versus-leukaemia activity associated with both acute and chronic GVHD may reduce the risk of leukaemia relapse. Prophylaxis of acute GVHD usually consists of in vivo post-grafting immunosuppression with cyclosporin alone or in combination with methotrexate; methotrexate alone can be considered in leukaemia patients with a high risk of relapse. In recent years, tacrolimus is increasingly being used instead of cyclosporin, alone or in combination with methotrexate. In vitro T cell depletion in paediatric patients is usually reserved for those with transplants from partially matched family donors or unrelated volunteers. The treatment of patients with grades II to IV acute GVHD should be immediate and aggressive, as the quality and duration of the response directly correlates with survival. The overall response rate to treatment is often unsatisfactory, ranging from 40 to 50% of cases. First-line treatment usually consists of corticosteroids. In patients not responding to corticosteroids, antilymphocyte globulin and monoclonal antibodies directed towards lymphocytes and/or cytokines produced during GVHD are employed, but with variable success. Patients experiencing acute GVHD are also prone to develop chronic GVHD. whose classical treatment is based on the use of cyclosporin and corticosteroids. More recently, encouraging results in the treatment of patients with chronic GVHD have been reported with the use of extracorporeal photochemotherapy. Other drugs, such as ursodeoxycholic acid, etretinate and clofazimine, are under evaluation.

Extracorporeal photochemotherapy does not suppress T- or B-cell responses to novel or recall antigens

BACKGROUND

Extracorporeal photopheresis (ExP) is an effective therapy for several conditions including cutaneous T-cell lymphoma, scleroderma, and allograft rejection. Experimental animal models suggest that ExP may induce antigen-specific immunosuppression.

OBJECTIVE

Our purpose was to determine the effect of photopheresis on humoral and cell-mediated immunity in human subjects.

METHODS

Recall and primary immune responses of patients with scleroderma receiving monthly ExP treatments were assessed by delayed type hypersensitivity skin tests, T-cell proliferative responses after immunizations with tetanus toxoid and keyhole limpet hemocyanin, and serum antibody titers against common viral pathogens.

RESULTS

After 6 months of ExP, viral antibody titers and delayed type hypersensitivity responses were not significantly different from baseline values in all 7 patients tested. T-cell responses to tetanus toxoid remained normal in 3 of 3 patients tested for a minimum of 6 months after booster immunization. Immunization with the protein antigen keyhole limpet hemocyanin after initiation of ExP therapy resulted in sustained T-cell proliferative responses up to 6 months in 3 of 3 patients.

CONCLUSION

These results, along with the observation of no increased incidence of opportunistic infections or neoplasms, suggest that ExP is not broadly immunosuppressive and does not prevent primary responses to vaccination or other antigenic challenges.

Extracorporeal photochemotherapy for Epstein-Barr virus-associated lymphoma after lung transplantation

Posttransplantation lymphoproliferative disorder (PTLD) is a serious complication after transplantation of solid organs. Highest incidence rates have been reported for lung transplant recipients. With the current treatment strategy for early onset PTLD, a reduction of immunosuppressive drugs, mortality of lung transplant recipients with PTLD remains high, due to both, incomplete control of PTLD and transplant rejection. We present a lung transplant recipient with a history of acute rejection and Epstein Barr virus-associated posttransplantation malignant non-Hodgkin's lymphoma. Extracorporeal photochemotherapy, in combination with a moderate reduction of immunosuppressive therapy, resulted in complete disappearance of PTLD. After a first year of follow-up, no further rejection and no recurrence of PTLD have occurred. Treatment with ECP, with its beneficial effects on both, rejection after organ transplantation and malignant lymphoma, may be a particularly valuable approach for the treatment of PTLD in patients after lung transplantation, with its increased risk for transplant rejection.

Therapeutic plasma exchange and cytapheresis in pediatric patients

Pediatric therapeutic apheresis is reviewed including what it is, how it is performed and indications for its use. Pediatric patients are special, and the unique needs for replacement fluids and attention to access, anticoagulation, volume shifts and hypothermia are stressed. While all indications cannot be addressed, the procedures most commonly performed are reviewed. These include erythrocytapheresis, leukaphereses and plasma exchanges. A table details the strength of evidence supporting the use of apheresis procedures for many of these indications.

The North American experience with photopheresis

Photopheresis or extracorporeal photochemotherapy (ECP) is a novel immunomodulatory therapy based upon pheresis of light-sensitive cells. Whole blood is removed from patients who have previously ingested the photosensitizing agent 8-methoxypsoralen (8-MOP) followed by leukapheresis and exposure of the 8-MOP containing white blood cells (WBCs) extracorporeally to an ultraviolet A (UVA) light source prior to their return to the patient. In 1988, the Food and Drug Administration (FDA) approved photopheresis for the treatment of cutaneous T-cell lymphoma (CTCL). Treatment of CTCL with photopheresis has been reported in over 300 patients worldwide. Photopheresis has also demonstrated encouraging results in the treatment of solid organ transplant rejection, graft versus host disease, scleroderma, and other autoimmune diseases although fewer patients have been studied. This review will focus on the North American experience with photopheresis.