Primate cardiac allo-and xenotransplantation: modulation of the immune response with photochemotherapy

CD11c+ dendritic cells mediate antigen-specific suppression in extracorporeal photopheresis

Extracorporeal photopheresis (ECP) represents one of the most widespread and effective cell therapies for graft‐versus‐host disease and other T cell‐mediated disorders. However, the key factors affecting the therapeutic efficacy of ECP remain unclear. We hypothesized that therapeutic effects are mediated by ECP‐treated antigen‐presenting dendritic cells (DC). To test this hypothesis, we used the experimental model of contact hypersensitivity (CHS). The ECP’s therapeutic activity improved when the total cell dose of the ECP‐treated cells was increased. We used different haptens during sensitization to demonstrate that the anti‐inflammatory activity of ECP is antigen‐specific. This confirmed the hypothesis that professional antigen‐presenting cells are involved in the mode of action. Also, the ECP’s therapeutic activity was abrogated by the depletion of CD11c⁺ DC, which represents fewer than 1% of all the ECP‐exposed cells. Finally, we confirm the critical importance of CD11c⁺ DC for ECP activity by showing that only a few purified CD11c⁺ DC are sufficient to mediate its therapeutic effect. The finding that ECP‐treated, physiological antigen‐presenting DC alone mediate antigen‐specific modulation of a pathological immune response may result in better‐targeted interventions when treating patients.

Extracorporeal Photochemotherapy after Cardiac Transplantation: A New Therapeutic Approach to Allograft Rejection

Photopheresis (ECP) is a new immunomodulatory therapy in which recipient lymphocytes are treated extracorporeally with 8-methoxypsoralen and ultraviolet light. The treatment seems to induce an inhibition of both humoral and cellular rejection after transplantation.

Objective

Since recurrent rejection (RR) continues to be a severe complication after heart transplantation (HTx) and the immunosuppressive regimes used for the treatment are often associated with increased morbidity and mortality, we investigated whether ECP could have a beneficial effect on the number and severity of rejection episodes.

Methods

Eleven HTX recipients (5 M and 6 F, mean age 48.5 yrs) with RR were enrolled in the study. ECP was performed at weekly intervals during the 1st month, at 2 week intervals during the 2nd and 3rd month, and then monthly for another 3 months.

Results

The fraction of biopsies (EMB) with a grade 0/1A rejection increased during ECP from 46% to 72% while the EMB showing a 3A/3B rejection decreased from 42% to 18%. It is also noteworthy that out of the 78 EMB performed during ECP only one showed a 3B rejection in comparison with 13 out of 110 EMB in the pre-ECP period. Six rejection relapses were observed in a total follow-up of 60 months, two of them occurring during the tapering of oral steroid. Four relapses were reversed by ECP, one by IV steroids and the last by methotrexate after the failure of both IV steroids and ECP. The mean doses of immunosuppressive drugs resulted lower after 6 months of ECP: steroids were reduced from 13 to 8.25 mg/day, cyclosporine from 375 to 285 mg/day, azathioprine from 55 to 35 mg/day.

Conclusions

ECP is a well tolerated treatment. Its administration allows better RR control and significant reduction in immunosuppressive therapy. (Int J Artif Organs 2000; 23: 49–54)

Extracorporeal photopheresis: technique, established and novel indications

Extracorporeal photopheresis (ECP) has had a major impact in the treatment of various conditions in the past 25 years. Although it was initially developed for the treatment of patients with resistant cutaneous T cell lymphoma (CTCL), this therapy was later used to treat recipients of solid organs and stem cell transplants with rejection or graft-versus-host disease (GVHD), respectively. A significant number of patients with CTCL can achieve long term remission with ECP therapy. Those patients with heart or lung transplants may experience fewer or shorter rejection episodes following ECP. Furthermore, patients that respond to ECP can generally reduce the dose of immunosuppression medication, thus minimizing the morbidity caused by drugs such as corticosteroids and calcineurin inhibitors. While the exact mechanism of action of ECP is not well-understood, evidence suggests that reinfusion of the patient's apoptotic white blood cells, the ultimate product of ECP, promotes immunomodulatory events that are beneficial in patients with CTCL, transplant rejection, GVHD, and possibly other inflammatory conditions.

Updating ECP action mechanisms

Extracorporeal Photochemotherapy (ECP) consists in illumination of the patient's leukocytes in the presence of 8-Methoxy Psoralen (8-MOP) and its reinjection to the same patient. ECP is responsible for many cellular events, the most important being the induction of cell apoptosis. Apoptosis appears first in lymphocytes and activated lymphocytes (allo or auto) which are more sensitive and undergo faster apoptosis rather than other cells. Monocytes develop apoptosis later. The injection of apoptotic cells induces tolerance in patients with graft versus host disease (GvHD) and acute heart or lung graft rejection. In these patients, phagocytosis of apoptotic cells by antigen-presenting cells (APCs) and in particular dendritic cells is responsible for a shift from Th1 to Th2 immune response, an increase in anti-inflammatory cytokines such as interleukine 10 (IL-10) and Tumor Growth Factor Beta (TGF-β), a decrease in pro-inflammatory cytokines and finally, for the proliferation of regulatory cells. Among CD4/CD25 positive cells, only CD4(+)CD25(hi) are T-regulatory cells (T-regs). One subpopulation of T-regs produces IL-10 and inhibits Th1 CD4 cells, whereas other populations act as suppressors and inhibit the cytotoxic T-cells responsible for organ rejection and GvHD in an antigen specific fashion. It is not clear why the injection of early apoptotic cells induces tolerance in GvHD and organ graft rejection, but in Sézary syndrome, it induces up-regulation of anti-tumor immune response. Immune response modulation (up- or down-regulation) after ECP depends on many factors: early apoptotic cell injection; anti-inflammatory environment; impaired function of dendritic cells; dendritic type 2 cell dominance, lead to immune tolerance, whereas late apoptotic or necrotic cell injection and pro-inflammatory cytokines enhance immune response. Therefore, immune response to ECP depends on various factors responsible for the diversity of its mode of action in different diseases and further investigations are required.

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

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

The molecular and clinical rationale of extracorporeal photochemotherapy in autoimmune diseases, malignancies and transplantation

Extracorporeal photochemotherapy, or photopheresis is a low-risk therapeutical intervention, which has been introduced in a variety of hematological malignancies, autoimmune conditions and transplantation. The mode of action of photopheresis encompasses apoptosis-induction and modifications of immunoregulatory processes, leading to the elimination of malignant cells, as well as the down-modulation of harmful immune responses. Although the beneficial effects of the therapy have been depicted in numerous studies, little is known about the exact benefits and the molecular mechanisms behind. The aim of the present review was to portray some aspects of the molecular and clinical rationale of extracorporeal photochemotherapy in autoimmune diseases, malignancies and transplantation, and to provide an overview of the treatment in the modern clinical management of these diseases.

Extracorporeal photopheresis: Lighting the way to immunomodulation

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

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.

Mechanisms of action of extracorporeal photochemotherapy in the control of GVHD: involvement of dendritic cells

Despite the fact that extracorporal photochemotherapy (ECP) is now broadly used for the treatment of graft versus host disease or T-cell lymphomas, the mechanisms of its action remain enigmatic. This work provides a synthesis of the main results suggesting the initiation by ECP of an immune reaction responsible for the down modulation of pathogenic T-cell functions, with a special focus on the role of dendritic cells in this phenomenon.

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.

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.

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, 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.

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.

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

BACKGROUND

Photopheresis is an immunoregulatory technique in which lymphocytes are reinfused after exposure to a photoactive compound (methoxsalen) and ultraviolet A light. We performed a preliminary study to assess the safety and efficacy of photopheresis in the prevention of acute rejection of cardiac allografts.

METHODS

A total of 60 consecutive eligible recipients of primary cardiac transplants were randomly assigned to standard triple-drug immunosuppressive therapy (cyclosporine, azathioprine, and prednisone) alone or in conjunction with photopheresis. The photopheresis group received a total of 24 photopheresis treatments, each pair of treatments given on two consecutive days, during the first six months after transplantation. The regimen for maintenance immunosuppression, the definition and treatment of rejection episodes, the use of prophylactic antibiotics, and the schedule for cardiac biopsies were standardized among all 12 study centers. All the cardiac-biopsy samples were graded in a blinded manner at a central pathology laboratory. Plasma from the subgroup of 34 patients (57 percent) who were enrolled at the nine U.S. centers was analyzed by polymerase-chain-reaction amplification for cytomegalovirus DNA.

RESULTS

After six months of follow-up, the mean (+/-SD) number of episodes of acute rejection per patient was 1.44+/-1.0 in the standard-therapy group, as compared with 0.91+/-1.0 in the photopheresis group (P=0.04). Significantly more patients in the photopheresis group had one rejection episode or none (27 of 33) than in the standard-therapy group (14 of 27), and significantly fewer patients in the photopheresis group had two or more rejection episodes (6 of 33) than in the standard-therapy group (13 of 27, P=0.02). There was no significant difference in the time to a first episode of rejection, the incidence of rejection associated with hemodynamic compromise, or survival at 6 and 12 months. Although there were no significant differences in the rates or types of infection, cytomegalovirus DNA was detected significantly less frequently in the photopheresis group than in the standard-therapy group (P=0.04).

CONCLUSIONS

In this pilot study, the addition of photopheresis to triple-drug immunosuppressive therapy significantly decreased the risk of cardiac rejection without increasing the incidence of infection.

Clinical and mechanistic aspects of photopheresis

Photopheresis is an extracorporeal form of photochemotherapy with 8-methoxypsoralen (8-MOP) and ultraviolet A (UVA) radiation. Photopheresis is used for the management of T-cell-mediated diseases, and such treatment leads to the induction of antigen-specific immune suppression directed to the pathogenic clone of T cells. Photopheresis is used to treat a wide variety of diseases--such as cutaneous T-cell lymphoma, systemic sclerosis; rheumatoid arthritis, lupus erythematosus--and is also successfully applied in the suppression of graft rejection. In addition to the clinical achievements, attention will be paid to results from animal studies. An important outcome of these studies is that photopheresis can be used to treat airway hyperreactivity. Furthermore, it was shown that the therapeutic strategy can be changed drastically: the presence of plasma during irradiation should be avoided and the amount of blood that must be treated to obtain the desired antigen-specific immunosuppression can be greatly decreased. Also, results from cellular experiments are discussed. An example of this is the increase in the major histocompatibility complex expression on the surface of cells found after treatment. The mechanism that underlies photopheresis has not yet been elucidated, but progress has been made. The following related points will be reviewed: models for investigation; and mechanistic aspects, with the emphasis on cellular biomacromolecules and on photosensitizers (drugs) other than 8-MOP.

Extracorporeal photochemotherapy: a treatment for organ graft rejection

Extracorporeal photochemotherapy (ECPC) has been investigated experimentally and in clinical conditions in transplant rejection treatment and prevention. Repeated injections of photochemically modified syngeneic alloreactive T cells prior to transplant significantly delay rejection in a mouse skin graft model as well as in a heterotopic heart transplant model in rats. In the latter, we found this effect to be dependent on 3 main parameters, i.e., treatment intensity (number of injections), schedule (injections before and after transplant), and associated immunosuppression (because there is no detectable effect in animals without immunosuppression). In human beings, ECPC was first used for the treatment of acute rejection episode after heart transplantation. At least 2 studies provided evidence that ECPC is as effective as high dose corticosteroids in controlling moderate acute rejections, and several case reports showed that ECPC could be effective in recurrent and/or steroid resistant rejections. ECPC has also been investigated in an open trial to prevent rejection episodes after heart transplantation in patients at high risk of acute rejection because of human leukocyte antigen (HLA) immunization and/or a second or third transplant and found to be successful. In heart transplant recipients at standard risk of rejection episodes, a small scale randomized trial showed a reduction in both rejection episodes and infections in the ECPC treated vs. the standard group. Beyond these studies and other isolated case reports, several large scale randomized trials in heart, lung, and even kidney transplantations (some of them already ongoing), will enable us to define the role of ECPC in the management of transplant recipients.

Immunomodulation in transplantation with photopheresis

Photopheresis is a technique in which peripheral blood mononuclear cells, in the presence of a photoactivatable compound, are exposed extracorporeally to ultraviolet A light and reinfused, inducing a host autoregulatory immune response. Experimental work and ongoing clinical studies are helping to define the role of this novel, safe, and non-toxic immunomodulating technology in the field of transplantation.

Review of immunomodulation by photopheresis: treatment of cutaneous T-cell lymphoma, autoimmune disease, and allograft rejection

Photopheresis is an apheresis-based therapy that is currently available at approximately 70 medical centers worldwide. Recent evidence indicates that extracorporeal photopheresis can significantly prolong life as well as induce a 60-75% response rate among individuals with advanced cutaneous T-cell lymphoma (CTCL). Moreover, a 10-15% cure rate, in response to photopheresis alone, or in combination with interferon-alpha, has been obtained at our institution. These complete responses have been characterized by the complete disappearance of morphologically atypical cells from the skin and blood. Southern blot analysis of peripheral blood specimens has also confirmed the indefinite disappearance of the malignant T-cell clone from the blood of patients with complete responses. Current immunological data obtained from in vitro human studies and from animal models suggest that the basis for the responses of CTCL patients are related to activation of treated macrophages resulting in release of cytokines, including substantial levels of tumor necrosis factor alpha (TNF-alpha), and perhaps, to the induction of anticlonotypic immunity directed against pathogenic clones of T lymphocytes. In addition to the treatment of CTCL, a potential role for photopheresis in the therapy of autoimmune disease has been suggested by recent pilot studies of pemphigus vulgaris, rheumatoid arthritis, and systemic lupus erythematosus. Furthermore, a randomized, single-blinded trial involving 79 patients with early onset, aggressive systemic sclerosis suggested that photopheresis could benefically affect the course of the cutaneous thickening in this form of the disease. Lastly, two independent pilot studies of cardiac transplantation have indicated that photopheresis can reverse acute cardiac allograft rejection and potentially suppress ongoing chronic rejection. Randomized, controlled trials for these new indications for photopheresis therapy are currently in the early stages of implementation.

Treatment of severe cardiac allograft rejection with extracorporeal photochemotherapy

Two patients were treated with photopheresis for marked cardiac allograft rejection with hemodynamic compromise that had become unresponsive to standard therapy. Multiple episodes of rejection had occurred, and initial response to standard therapy was favorable. However, progressive deterioration was documented by serial endomyocardial biopsies, fever, congestive heart failure, and abnormal cardiac catheterization findings. In the absence of retransplantation, death seemed imminent. Photopheresis was begun. Both patients received oral 8-methoxypsoralen and > or = 5 x 10(9) mononuclear cells were collected, treated with ultraviolet light A for 1.5 hours, and were reinfused. One procedure was performed weekly x4 and then monthly x5. Responses were striking with rapid loss of fever, improvement in exercise tolerance, normalization of cardiac hemodynamics, and improvement in endomyocardial biopsies. Although our experience with these two patients is anecdotal, photopheresis merits further study as treatment for severe cardiac allograft rejection.

Treatment of erythrodermic cutaneous T-cell lymphoma with extracorporeal photochemotherapy

BACKGROUND

This original cohort of patients with erythrodermic cutaneous T-cell lymphoma (CTCL) was reported to have clinical improvement with photopheresis during the 12 months of the original study. No long-term follow-up data have been available to examine the impact of this therapy on the disease.

OBJECTIVE

Our purpose was to provide long-term follow-up on the original 29 erythrodermic CTCL patients treated with photopheresis and to compare these results with historical controls.

METHODS

Files of patients from the original photopheresis study centers were reviewed and their current status was documented.

RESULTS

The median survival of the treated patients was 60.33 months from the date of diagnosis and 47.9 months from the date of the start of photopheresis therapy. A complete remission has been maintained in four of the six patients who achieved complete responses in the original study. The best responses were seen in patients with a lower CD4/CD8 ratio in the peripheral blood at the start of therapy.

CONCLUSION

Photopheresis can influence the natural history of erythrodermic CTCL by inducing remissions and prolonging survival with minimal toxicity.

Biochemical analysis of class I and class II MHC antigens in cynomolgus macaques by one-dimensional isoelectric focusing

To obtain a better estimate of major histocompatibility complex (MHC) polymorphism in the Old World macaque, Macaca fascicularis, class I and class II MHC proteins from 42 animals were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and one-dimensional isoelectric focusing (1D-IEF). The panel represented both related and unrelated animals with a total of at least 30 serologically distinct haplotypes. Cells were sequentially immunoprecipitated with monoclonal antibody (mAb) W6/32 for class I and with mAb L243 for class II molecules, followed by neuraminidase treatment. Both sets of immunoprecipitates yielded 5-7 major bands on IEF. All bands present in offspring were present in at least 1 parent. Siblings which were serologically identical for class I and which were non-stimulatory in mixed lymphocyte culture (MLC) yielded identical IEF patterns for both class I and class II; in other sibling pairs which were serologically identical for class I antigens (Ag), IEF produced convincing evidence that the siblings were indeed nonidentical, or helped to verify that recombination had occurred within the MHC. Specific bands were found which correlated with class I specificities A8, A24, and B25 previously defined by serology. Comparison of serological and biochemical data will broaden our understanding of the MHC in Macaca fascicularis and will increase the potential use of this species in transplantation research, as a model of disease, and for comparative studies.