Extracorporeal photopheresis after heart transplantation

Extracorporeal Photopheresis Enhances the Frequency and Function of Highly Suppressive FoxP3 + Treg Subsets in Heart Transplanted Individuals

BACKGROUND

Extracorporeal photopheresis (ECP) has emerged as a prophylactic and therapeutic immunomodulatory option for managing acute rejection in heart transplants (HTx). The underlying mechanisms through which ECP exerts its immunomodulatory effects remain under investigation. Regulatory T cells (Treg) are a heterogeneous subset of immune lymphocytes that ensure the maintenance of tissue homeostasis, avoiding graft rejection. The transcription factor forkhead box protein 3 (FoxP3) is an essential molecular marker of Treg, acting as a "master regulator" of their genesis, stability, and functions. No study has investigated whether ECP impacts FoxP3 expression and its highly suppressive variants containing the exon 2 (FoxP3-E2), particularly in HTx.

METHODS

In the current study, we recruited 14 HTx participants who had undergone ECP therapy. We explored the effect of in vivo ECP on CD4 + FoxP3 + Treg frequency and in vitro suppressive function in 8 HTx participants before (T0) and after 3 (T1), 6 (T2), and 12 (T3) mo of treatment. As a control group, we included 4 HTx individuals who had not undergone ECP therapy.

RESULTS

We found that ECP increases the frequency of CD4 + FoxP3 + Treg subset with highly suppressive phenotype, including CD4 + FoxP3-E2 + Treg. At functional levels, we observed that ECP treatment in HTx individuals effectively improves Treg suppressive ability in controlling the proliferation of autologous conventional CD4 + T lymphocytes.

CONCLUSIONS

Our findings collectively suggest that ECP exerts its immunomodulatory effects in HTx individuals by positively impacting the frequency and regulatory function of the FoxP3 + Treg compartment.

Extracorporeal photopheresis induces the release of anti-inflammatory fatty acids and oxylipins and suppresses pro-inflammatory sphingosine-1-phosphate

AIMS

Extracorporeal photopheresis (ECP) is a UVA-based phototherapy of whole blood and well established as a first line or combination therapy for the treatment of cutaneous T-cell lymphoma, systemic sclerosis, graft-versus-host disease and is used to control organ transplant rejection. While the proapoptotic activity on activated T-cells is evident, the clinical efficacy of this treatment also appears to be based on other yet unknown mechanisms. In this study, we aimed to identify novel mechanisms of ECP regardless of the patient's background situation.

MAIN METHODS

To better understand the immediate consequences of ECP, we analyzed blood plasma of patients with different ECP indications immediately before and after treatment with regard to proteins and lipid mediators.

KEY FINDINGS

While proteome profiling identified substantial inter-individual differences in the protein composition, no significant alteration was detectable upon treatment. In contrast, several fatty acids and lipid mediators were found to be significantly altered by ECP. Remarkably, upregulated lipid mediators including polyunsaturated fatty acids, 12-HEPE and 13-OxoODE have been described to be anti-inflammatory, while the downregulated molecules sphingosine-1-phosphate (S1P) and stearic acid are potent pro-inflammatory mediators. A selective sphingosine-1-phosphate-1 receptor (S1P1) modulator AUY954, which decreases S1P1 and experimentally reduces transplant rejection in vivo, showed greater anti-proliferative activity in human lung fibroblasts from COPD patients compared to normal lung fibroblasts, confirming that this pathway may be important in ECP and its mode of action.

SIGNIFICANCE AND OUTLOOK

In conclusion, we suggest that the ECP-induced changes in lipid mediators may contribute to the remarkable anti-inflammatory effects of the treatment. Depending on their lipid status, patients may benefit from novel treatment regimens combining ECP with lipid modulators. This could be used for the prevention of transplant organ rejection, the treatment of acute or chronic GvHD or transplant organ rejection and the long-term treatment of various skin diseases. This study uncovers novel mechanisms of ECP, that can be used to establish clinically relevant lipid profiles of patients to support patient stratification, predictive or prognostic purposes and thus personalized medical care in the framework of PPPM practice. A combination with S1P modulators may therefore have beneficial effects.

Extracorporeal photopheresis for the prevention of rejection after lung transplantation: a prospective randomised controlled trial

BACKGROUND

Lung transplant recipients have the worst long-term outcomes of all solid organs due to acute rejection and chronic lung allograft dysfunction (CLAD). Our objective was to investigate the efficacy of extracorporeal photopheresis (ECP) as a prophylactic treatment to prevent acute cellular rejection (ACR), cytomegalovirus (CMV) infections and reduce the risk of CLAD.

METHODS

This was a single-centre prospective randomised controlled trial conducted at the Medical University of Vienna (Vienna, Austria) between 2018 and 2020. It included 31 COPD recipients per group. The treatment group underwent ECP in addition to a standard triple-drug immunosuppression protocol after lung transplantation. The control group received standard triple-drug immunosuppressive therapy. The primary outcome was a composite outcome defined as incidence of high-grade ACR, CMV infection or CLAD within 24 months after lung transplantation.

RESULTS

In the control group, 19 patients (61.3%) achieved the primary combined end-point compared with only six patients (19.4%) in the treatment group (p<0.001). Freedom from high-grade ACR was significantly greater in the ECP group (p=0.045). Cumulative A scores were significantly lower in the ECP group than in the control group at 3 months (0.18±0.44 versus 0.56±0.94; p<0.05) and at 12 months (0.25±0.48 versus 1.0±1.45; p=0.002). The rate of infections was lower in the ECP group with five cases and 67 cumulative hospital days compared with 22 cases and 309 days in the control group (p=0.002). Freedom from CLAD at 3 years was significantly greater in the ECP group (p=0.015).

CONCLUSION

Adding ECP to standard triple immunosuppression resulted in a significant reduction of the number of ACR episodes and significantly lower incidence of CLAD.

The use of extracorporeal photopheresis in solid organ transplantation-current status and future directions

Prevention and management of allograft rejection urgently require more effective therapeutic solutions. Current immunosuppressive therapies used in solid organ transplantation, while effective in reducing the risk of acute rejection, are associated with substantial adverse effects. There is, therefore, a need for agents that can provide immunomodulation, supporting graft tolerance, while minimizing the need for immunosuppression. Extracorporeal photopheresis (ECP) is an immunomodulatory therapy currently recommended in international guidelines as an adjunctive treatment for the prevention and management of organ rejection in heart and lung transplantations. This article reviews clinical experience and ongoing research with ECP for organ rejection in heart and lung transplantations, as well as emerging findings in kidney and liver transplantation. ECP, due to its immunomodulatory and immunosuppressive-sparing effects, offers a potential therapeutic option in these settings, particularly in high-risk patients with comorbidities, infectious complications, or malignancies.

The value of extracorporeal photopheresis as an immunosuppression-modifying approach in solid organ transplantation: a potential solution to an unmet medical need

Allograft rejection is a critical issue following solid organ transplantation (SOT). Immunosuppressive therapies are crucial in reducing risk of rejection yet are accompanied by several significant side effects, including infection, malignancy, cardiovascular diseases, and nephrotoxicity. There is a current unmet medical need with a lack of effective minimization strategies for these side effects. Extracorporeal photopheresis (ECP) has shown potential as an immunosuppression (IS)-modifying technique in several SOT types, with improvements seen in acute and recurrent rejection, allograft survival, and associated side effects, and could fulfil this unmet need. Through a review of the available literature detailing key areas in which ECP may benefit patients, this review highlights the IS-modifying potential of ECP in the four most common SOT procedures (heart, lung, kidney, and liver transplantation) and highlights existing gaps in data. Current evidence supports the use of ECP for IS modification following SOT, however there is a need for further high-quality research, in particular randomized control trials, in this area.

Extracorporeal photopheresis in the treatment of cardiac allograft rejection: A single-centre experience

Despite novel immunosuppressive (IS) protocols, adverse effects of IS drugs continue to have notable negative impact on patient and cardiac allograft survival after heart transplantation (HTx). Therefore, IS regimens with less toxic side effects are sorely needed. We aimed to evaluate the efficacy of extracorporeal photopheresis (ECP) in combination with tacrolimus-based maintenance IS therapy in the treatment of allograft rejection in adult HTx recipients. Indications for ECP included acute moderate-to-severe or persistent mild cellular rejection, or mixed rejection. Twenty-two patients underwent a median of 22(2-44) ECP treatments after HTx. Median duration of ECP course was 173.5(2-466) days. No relevant adverse effects of ECP were noted. Reduction of methylprednisolone doses was safe throughout the ECP course. ECP, used in conjunction with pharmacological anti-rejection therapy, had a successful reversal of cardiac allograft rejection, decreased the rates of subsequential rejection episodes and normalized the allograft function in patients completing the ECP course. Short- and long-term survivals were excellent (91% at 1 and 5 years post-ECP) and comparable to International Society for Heart and Lung Transplantation registry data on HTx recipient overall survival. In conclusion, ECP can be safely used for the treatment and prevention of cardiac allograft rejection in conjunction with traditional IS regimen.

European multicenter study on the real-world use and clinical impact of extracorporeal photopheresis after heart transplantation

BACKGROUND

Aim of this study was to describe the real-world use of extracorporeal photopheresis (ECP) and assess its impact on clinical outcomes in the modern era of heart transplantation.

METHODS

Seven transplant centers from 5 European countries participated in this retrospective, observational, single-arm chart review study. All patients received ECP after heart transplantation in 2015 or later. Data were extracted from medical records between November 2020 and December 2021.

RESULTS

Overall, 105 patients were enrolled and followed for an average of 2 years after initiation of ECP. Reasons to start ECP were acute cellular rejection (35.2%), rejection prevention (32.4%), mixed rejection (18.1%), and antibody-mediated rejection (14.3%). Rejection ISHLT grades improved from start to end of ECP treatment in 92% of patients treated with ECP for rejection. Of patients who started ECP to prevent rejection, 88% remained free from any rejection despite a reduction of calcineurin inhibitors. Overall survival was 95%, and no deaths were related to ECP. Safety events occurred in 18 patients, of which 13 experienced complications with venous access.

CONCLUSIONS

This study, the largest European ECP study in heart transplantation, demonstrates that ECP can effectively be used to treat different rejection types and to prevent rejection in the modern era of immunosuppression. Patients with rejections who have received ECP have shown high response as measured by histological improvements in ISHLT classification. A high percentage of patients in the prevention group remained free from rejection despite reduction in immunosuppression, in particular calcineurin inhibitors.

Pre-transplant infusion of donor leukocytes treated with extracorporeal photochemotherapy induces immune hypo-responsiveness and long-term allograft survival in murine models

Recipients of solid organ transplantation (SOT) rely on life-long immunosuppression (IS), which is associated with significant side effects. Extracorporeal photochemotherapy (ECP) is a safe, existing cellular therapy used to treat transplant rejection by modulating the recipient’s own blood cells. We sought to induce donor-specific hypo-responsiveness of SOT recipients by infusing ECP-treated donor leukocytes prior to transplant. To this end, we utilized major histocompatibility complex mismatched rodent models of allogeneic cardiac, liver, and kidney transplantation to test this novel strategy. Leukocytes isolated from donor-matched spleens for ECP treatment (ECP-DL) were infused into transplant recipients seven days prior to SOT. Pre-transplant infusion of ECP-DL without additional IS was associated with prolonged graft survival in all models. This innovative approach promoted the production of tolerogenic dendritic cells and regulatory T-cells with subsequent inhibition of T-cell priming and differentiation, along with a significant reduction of donor-specific T-cells in the spleen and grafts of treated animals. This new application of donor-type ECP-treated leukocytes provides insight into the mechanisms behind ECP-induced immunoregulation and holds significant promise in the prevention of graft rejection and reduction in need of global immune suppressive therapy in patients following SOT.

UK national survey of anticoagulation in extra-corporeal photopheresis-Is it time for a UK consensus statement?

BACKGROUND

Extra-corporeal photopheresis (ECP) requires anticoagulation to prevent circuit clotting. Unfractionated heparin (UFH) is currently the only anticoagulant licensed for the ECP system in use in the United Kingdom (UK). Acid citrate dextrose-A (ACD-A) is the preferred anticoagulant for most other apheresis procedures. Anecdotal evidence suggested variability in ECP practice across the UK with some providers using off-label ACD-A.

AIMS

We developed a survey together with the UK Photopheresis Society to establish current practice.

MATERIALS & METHODS

This was distributed to all 17 ECP providers covering 34 UK sites.

RESULTS

Significant variability in practice was demonstrated with only 36% of responding providers (5/14) using UFH exclusively and 29% (4/14) using ACD-A as standard.

CONCLUSION

This survey highlights the need for a UK consensus.

Immune Monitoring Assay for Extracorporeal Photopheresis Treatment Optimization After Heart Transplantation

Background

Extracorporeal photopheresis (ECP) induces immunological changes that lead to a reduced risk of transplant rejection. The aim of the present study was to determine optimum conditions for ECP treatment by analyzing a variety of tolerance-inducing immune cells to optimize the treatment.

Methods

Ten ECP treatments were applied to each of 17 heart-transplant patients from month 3 to month 9 post-HTx. Blood samples were taken at baseline, three times during treatment, and four months after the last ECP treatment. The abundance of subsets of tolerance-inducing regulatory T cells (T_regs) and dendritic cells (DCs) in the samples was determined by flow cytometry. A multivariate statistical model describing the immunological status of rejection-free heart transplanted patients was used to visualize the patient-specific immunological improvement induced by ECP.

Results

All BDCA⁺ DC subsets (BDCA1⁺ DCs: p < 0.01, BDCA2⁺ DCs: p < 0.01, BDCA3⁺ DCs: p < 0.01, BDCA4⁺ DCs: p < 0.01) as well as total T_regs (p < 0.01) and CD39⁺ T_regs (p < 0.01) increased during ECP treatment, while CD62L⁺ T_regs decreased (p < 0.01). The cell surface expression level of BDCA1 (p < 0.01) and BDCA4 (p < 0.01) on DCs as well as of CD120b (p < 0.01) on T_regs increased during the study period, while CD62L expression on T_regs decreased significantly (p = 0.04). The cell surface expression level of BDCA2 (p = 0.47) and BDCA3 (p = 0.22) on DCs as well as of CD39 (p = 0.14) and CD147 (p = 0.08) on T_regs remained constant during the study period. A cluster analysis showed that ECP treatment led to a sustained immunological improvement.

Conclusions

We developed an immune monitoring assay for ECP treatment after heart transplantation by analyzing changes in tolerance-inducing immune cells. This assay allowed differentiation of patients who did and did not show immunological improvement. Based on these results, we propose classification criteria that may allow optimization of the duration of ECP treatment.

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.

Therapeutic apheresis in kidney transplantation: An updated review

Therapeutic apheresis is a cornerstone of therapy for several conditions in transplantation medicine and is available in different technical variants. In the setting of kidney transplantation, immunological barriers such as ABO blood group incompatibility and preformed donor-specific antibodies can complicate the outcome of deceased- or living- donor transplantation. Postoperatively, additional problems such as antibody-mediated rejection and a recurrence of primary focal segmental glomerulosclerosis can limit therapeutic success and decrease graft survival. Therapeutic apheresis techniques find application in these issues by separating and selectively removing exchanging or modifying pathogenic material from the patient by an extracorporeal aphaeresis system. The purpose of this review is to describe the available techniques of therapeutic aphaeresis with their specific advantages and disadvantages and examine the evidence supporting the application of therapeutic aphaeresis as an adjunctive therapeutic option to immunosuppressive agents in protocols before and after kidney transplantation.

Indication-specific immunomodulatory effects of extracorporeal photopheresis: A pilot study in heart transplanted patients

BACKGROUND

The clinical use of extracorporeal photopheresis (ECP) is based on its ability to induce cell-mediated immune tolerance towards foreign and self-antigens. Up-to-date, no clear consensus consists on how to use ECP after heart transplantation (HTx). In this pilot study, we evaluated the stimulatory effects of ECP on immune cells in HTx patients.

METHODS

HTx patients received ECP therapy as prophylaxis of rejection (PRX, n = 15), to treat acute cellular rejection (ACR, n = 13) or cardiac allograft vasculopathy (CAV, n = 5). Three ECP cycles with monthly frequency were performed. Blood samples were taken before every ECP cycle and 2 months after the last ECP cycle and were analyzed for cytokines and the tolerance-inducing cell subsets regulatory T cells (T_regs ), myeloid (mDCs), and plasmacytoid dendritic cells (pDCs).

RESULTS

While ECP treatment induced first an increase of pDCs in the CAV group (baseline: 22.0% ± 9.6%, prior third ECP cycle: 8.6% ± 3.2%, follow-up: 31.5% ± 8.4%, P = .009), no significant changes of DC subsets and T_regs were observed in the ACR- and in the PRX group. Furthermore, analysis of the immune balance showed different response profiles of pro- and anti-inflammatory cytokines among prophylactically ECP-treated patients and ECP-treated patients suffering from CAV or ACR.

CONCLUSIONS

In our pilot study, we showed different stimulatory effects of ECP on pDCs and cytokines among prophylactic and therapeutic ECP therapy after HTx. Immunological monitoring should be included in a larger clinical study of ECP treatment following HTx and to identify predictable parameters for ECP efficacy.

Extracorporeal Photopheresis-An Overview

Extracorporeal photopheresis (ECP) has been in clinical use for over three decades after receiving FDA approval for the palliative treatment of the Sézary Syndrome variant of cutaneous T-cell lymphoma (CTCL) in 1988. After the first positive experiences with CTCL, additional indications have been successfully explored including areas such as graft-vs.-host disease (GVHD), scleroderma, and solid organ transplantation. The mechanism of action is still not fully resolved, but important steps in understanding ECP in recent years have been very informative. Originally, the primary hypothesis stated that psoralen and ultraviolet A (UVA) in combination induce apoptosis in the treated immune cells. This view shifted in favor of dendritic cell initiation, modification of the cytokine profile and stimulation of several T-cell lineages, in particular regulatory T-cells. A number of ECP guidelines have been produced to optimize treatment regimens in the clinical context. In CTCL, enough evidence is available for the use of ECP as a first line treatment for Sézary Syndrome (SS), but also as a second line or rescue treatment in therapy-refractory forms of mycosis fungoides (MF). ECP in the treatment of acute and chronic GVHD has shown promising results as second line therapy in steroid-refractory presentations. In solid organ transplantation, ECP has been used to increase tissue tolerance and decrease infections with opportunistic pathogens, attributed to the use of high doses of immunosuppressive medication. Infection with cytomegalovirus (CMV) remains a limiting factor affecting survival in solid organ transplantation and the role of ECP will be discussed in this review. A trend toward prophylactic use of ECP can be observed and may further contribute to improve the outcome in many patients. To further deepen our knowledge of ECP and thus facilitate its use in patients that potentially benefit most from it, future prospective randomized trials are urgently needed in this rapidly growing field. The aim of this review is to (1) introduce the method, (2) give an overview where ECP has shown promising effects and has become an essential part of treatment protocols, and (3) to give recommendations on how to proceed in numerous indications.

Extracorporeal Photochemotherapy Drives Monocyte-to-Dendritic Cell Maturation to Induce Anticancer Immunity

Extracorporeal photochemotherapy (ECP) is a cancer immunotherapy for cutaneous T-cell lymphoma (CTCL) operative in more than 350 centers worldwide. Although its efficacy and favorable safety profile have driven its widespread use, elucidation of its underlying mechanism has been difficult. In this study, we identify the principal contributors to the anticancer immunotherapeutic effects of ECP, with the goal of enhancing potency and broadening applicability to additional malignancies. First, we scaled down the clinical ECP leukocyte-processing device to mouse size. Second, we used that miniaturized device to produce a cellular vaccine that regularly initiated therapeutic antimelanoma immunity. Third, we individually subtracted key factors from either the immunizing inoculum or the treated animal to ascertain their contribution to the in vivo antimelanoma response. Platelet-signaled monocyte-to-dendritic cell (DC) differentiation followed by sorting/processing/presentation of tumor antigens derived from internalized apoptotic tumor cells were absolute requirements. As in clinical ECP, immunogenic cell death of tumor cells was finely titrated by DNA cross-linkage mediated by photoactivated 8-methoxypsoralen (8-MOPA). ECP-induced tumor-loaded DC were effective immunotherapeutic agents only if they were spared exposure to 8-MOPA, indicating that healthy DC are required for ECP. Infusion of responder T cells into naïve tumor-challenged mice established the protective role of stimulated T-cell antitumor immunity. Collectively, these results reveal that selective antitumor effects of ECP are initiated by tumor antigen-loaded, ECP-induced DC, which promote potent collaboration between CD4 and CD8 tumor-specific T cells. These mechanistic insights suggest potential therapeutic applicability of ECP to solid tumors in addition to CTCL.Significance: These findings identify principal cellular contributors to the anticancer immunotherapeutic impact of ECP and suggest this treatment may be applicable to a broad spectrum of immunogenic malignancies. Cancer Res; 78(14); 4045-58. ©2018 AACR.

The clinical impact of donor-specific antibodies in heart transplantation

Donor-specific antibodies (DSA) are integral to the development of antibody-mediated rejection (AMR). Chronic AMR is associated with high mortality and an increased risk for cardiac allograft vasculopathy (CAV). Anti-donor HLA antibodies are present in 3-11% of patients at the time of heart transplantation (HTx), with de novo DSA (predominantly anti-HLA class II) developing post-transplant in 10-30% of patients. DSA are associated with lower graft and patient survival after HTx, with one study suggesting a three-fold increase in mortality in patients who develop de novo DSA (dnDSA). DSA against anti-HLA class II, notably DQ, are at particularly high risk for graft loss. Although detection of DSA is not a criterion for pathologic diagnosis of AMR, circulating DSA are found in almost all cases of AMR. MFI thresholds of ~5000 for DSA against class I antibodies, 2000 against class II antibodies, or an overall cut-off of 5-6000 for any DSA, have been suggested as being predictive for AMR. There is no firm consensus on pre-transplant strategies to treat HLA antibodies, or for the elimination of antibodies after diagnosis of AMR. Minimizing the risk of dnDSA is rational but data on risk factors in HTx are limited. The effect of different immunosuppressive regimens is largely unexplored in HTx, but studies in kidney transplantation emphasize the importance of adherence and maintaining adequate immunosuppression. One study has suggested a reduced risk for dnDSA with rabbit antithymocyte globulin induction. Management of DSA pre- and post-HTx varies but typically most centers rely on a plasmapheresis or immunoadsorption, with or without rituximab and/or intravenous immunoglobulin. Based on the literature and a multi-center survey, an algorithm for a suggested surveillance and therapeutic strategy is provided.

Infusion of Lymphocytes Treated With 8-Methoxypsoralen and Ultraviolet A Light Induces CD19+IL-10+ Regulatory B Cells and Promotes Skin Allograft Survival

Extracorporeal photopheresis (ECP) represents an alternative to immunosuppression as a means of reducing rejection after thoracic organ transplantation. The mechanism by which ECP exerts its protective effects, until now, has remained elusive. Infusion of ECP-treated splenic lymphocytes (PUVA-SP) can induce CD4⁺CD25^highFoxp3⁺ regulatory T cells. However, the regulatory effect of PUVA-SP on B cells remains poorly understood. In the present study, we measured IL-10 secretion from CD19⁺ B cells of peripheral blood mononuclear cells. Our results demonstrate that infusion of PUVA-SP (PUVA-BSP from BALB/c or PUVA-CSP from C57BL/6 mice), in the absence of an immunosuppressant, significantly promotes skin allograft survival. This effect was associated with upregulation of circulating regulatory B cells exhibiting preferential IL-10 secretion and a shift of cytokine profile from helper T cell type 1 to helper T cell type 2. Our results suggest that effective treatments involving infusion of PUVA-SP is likely related not only to the modulation of T cell and regulatory T cell functions but also to the function of B cell and regulatory B cells.