Photoactivated 8-methoxypsoralen treatment causes a peptide-dependent increase in antigen display by transformed lymphocytes

Multidisciplinary Approach to the Diagnosis and Therapy of Mycosis Fungoides

Mycosis fungoides is the most common primary cutaneous T-cell lymphoma, characterized by skin-homing CD4+ T cells derivation, indolent course, and low-grade of malignancy. Mycosis fungoides's classic type typically onsets with cutaneous erythematous patches, plaque, and tumor. In WHO-EORTC classification, folliculotropic mycosis fungoides, pagetoid reticulosis, and granulomatous slack skin are recognized as distinct variants of mycosis fungoides, because of their clinical and histological features, behavior, and /or prognosis. Mycosis fungoides often shows diagnostic difficulties, due to its absence of specific features and lesional polymorphism. A patient's treatment requires staging. In about 10% of cases, mycosis fungoides can progress to lymph nodes and internal organs. Prognosis is poor at advanced stage and management needs a multidisciplinary team approach. Advanced stage disease including tumors, erythroderma, and nodal, visceral, or blood involvement needs skin directed therapy associated with systemic drugs. Skin directed therapy includes steroids, nitrogen mustard, bexarotene gel, phototherapy UVB, and photochemiotherapy, i.e., total skin electron radiotherapy. Systemic therapies include retinoids, bexarotene, interferon, histone deacetylase inhibitors, photopheresis, targeted immunotherapy, and cytotoxic chemotherapy. Complexity of mycosis fungoides associated with long-term chronic evolution and multiple therapy based on disease stage need a multidisciplinary team approach to be treated.

Extracorporeal Photopheresis: A Case of Immunotherapy Ahead of Its Time

Extracorporeal photopheresis (ECP) is a cell-based immunotherapy that involves the reinfusion of autologous leukocytes after exposure to psoralen and UVA. The treatment has been used for over 30 years, at first on patients with cutaneous T-cell lymphoma (CTCL) and later for the management of patients with graft-versus-host disease (GvHD), sclerosing disorders, atopic dermatitis, and other diseases that may share the common driving factor of a pathogenic T-cell clone or clones in blood circulation. Patients with clinical improvement mount an antigen-specific immune response that may have tolerance traits in the case of GvHD or anticlonal cytotoxic characteristics in the case of CTCL. The exact mechanisms that dictate one response or the other are not fully understood, but the evidence accumulated so far indicates that multiple events occur simultaneously and consequentially contribute to the end result. These include contact of cells with the outside (plastics and tubing of the ECP apparatus), exposure to psoralen and UVA that activates platelets, monocytes, and other myeloid cells, the release of damage-associated molecular patterns, differentiation of monocytes into dendritic cells, and generation and successive presentation of numerous antigens after the phagocytosis of apoptotic cells. Once reintroduced, the ECP product increases the frequency and activity of regulatory T cells (Tregs), shifts the systemic cytokine balance, and promotes extravasation of immune cells that together shape the effects of this treatment. In this review, we summarize the seminal work and most recent literature of the therapeutic mechanisms and reflect on future avenues of improvements and applications of ECP.

Beta-2 microglobulin knockout K562 cell-based artificial antigen presenting cells for ex vivo expansion of T lymphocytes

Aim: The human K562 leukemia cell line as a scaffold of artificial antigen presenting cells (aAPCs) for ex vivo lymphocyte expansion does not usually express major histocompatibility complex (MHC) molecules. However, when stimulated by supernatants from human T lymphocyte cultures, K562 cells upregulate β-2 microglobulin (B2M) and MHC class I expression, which would induce allo-specific T cells. Methods: We disrupted the B2M locus in K562 cells by CRISPR/Cas9 and achieved MHC class I-negative K562 cells. Results: We further generated K562-based MHC class I-negative aAPC line by zinc-finger nuclease mediated insertion of costimulatory molecules into the AAVS1 locus. This aAPC line could attenuate allogeneic immune responses but support robust antigen-independent and CD19 antigen-specific chimeric antigen receptor-T cell expansion in vitro. Conclusion: B2M-knockout K562 cells provide a new scaffold for aAPC construction and broader application in adoptive immunotherapies.

Pruritus in cutaneous T-cell lymphoma: a review

BACKGROUND

Pruritus can be a distressing and even debilitating symptom for patients with cutaneous T-cell lymphoma (CTCL). To date, few studies have evaluated the pathophysiology of this symptom. Because of this, therapy for pruritus in CTCL has mainly relied on those therapies that target and treat the lymphoma. For patients living with CTCL that relapses or becomes refractory to treatment, and who continue to experience severe itch, this lymphoma-targeted treatment may not be enough to combat their pruritus. Therefore, other itch-targeted therapies are needed for use in this disease.

OBJECTIVE

We sought to evaluate the current evidence regarding the mechanism of action and treatments for pruritus associated with CTCL.

METHODS

An explicit and thorough search was restricted to all peer-reviewed literature available through MEDLINE (1950 to September 2011) and PubMed. Search terms used were "pruritus," "cutaneous T-cell lymphoma," "CTCL," "mycosis fungoides," "MF," and "Sézary syndrome." All studies that involved pruritus in CTCL, mycosis fungoides, or Sézary syndrome were evaluated by all 3 authors.

RESULTS

The current literature helps to identify therapies and possible mechanisms for treating patients with CTCL-associated pruritus.

LIMITATION

Most studies were preclinical. Only studies involving mechanisms of action or treatment were included.

CONCLUSION

A guideline is necessary to assist in the treatment of pruritus in CTCL and additional studies are necessary to uncover the exact mechanism or mechanisms of action.

Update on the mechanism of action and on clinical efficacy of extracorporeal photopheresis in the treatment of acute and chronic graft versus host disease in children

Extracorporeal photopheresis (ECP) has been used for treatment of steroid-refractory graft versus host disease (GVHD) with encouraging results. Although its exact mechanism of action is not fully understood, photoapheresed cells seem to induce a selective immune response directed against alloreactive T cell populations without causing generalized immunosuppression. Current pediatric experience with ECP for GVHD is available in the form of a few retrospective small studies concerning children with steroid refractory GVHD. Reviewing these data we conclude that ECP is a safe procedure, well tolerated even in low-weight pediatric patients, which warrants further evaluation in well-designed, prospective, controlled studies.

The role of extracorporeal photopheresis in the treatment of cutaneous T-cell lymphomas

Extracorporeal photochemotherapy (ECP) is an effective treatment modality for patients with erythrodermic myocosis fungoides (MF) and Sezary syndrome (SS). During ECP, a fraction of peripheral blood mononuclear cells is collected, incubated ex-vivo with methoxypsoralen, UVA irradiated, and finally reinfused to the patient. Although the mechanism of action of ECP is not well established, clinical and laboratory observations support the hypothesis of a vaccination-like effect. ECP induces apoptosis of normal and neoplastic lymphocytes, while enhancing differentiation of monocytes towards immature dendritic cells (imDCs), followed by engulfment of apoptotic bodies. After reinfusion, imDCs undergo maturation and antigenic peptides from the neoplastic cells are expressed on the surface of DCs. Mature DCs travel to lymph nodes and activate cytotoxic T-cell clones with specificity against tumor antigens. Disease control is mediated through cytotoxic T-lymphocytes with tumor specificity. The efficacy and excellent safety profile of ECP has been shown in a large number of retrospective trials. Previous studies showed that monotherapy with ECP produces an overall response rate of approximately 60%, while clinical data support that ECP is much more effective when combined with other immune modulating agents such as interferons or retinoids, or when used as consolidation treatment after total skin electron beam irradiation. However, only a proportion of patients actually respond to ECP and parameters predictive of response need to be discovered. A patient with a high probability of response to ECP must fulfill all of the following criteria: (1) SS or erythrodermic MF, (2) presence of neoplastic cells in peripheral blood, and (3) early disease onset. Despite the fact that ECP has been established as a standard treatment modality, no prospective randomized study has been conducted so far, to the authors' knowledge. Considering the high cost of the procedure, the role of ECP in the treatment of SS/MF needs to be clarified via well designed multicenter prospective randomized trials.

Understanding loss of donor white blood cell immunogenicity after pathogen reduction: mechanisms of action in ultraviolet illumination and riboflavin treatment

BACKGROUND

Donor white blood cells (WBCs) present in transfusion products can lead to immune sequelae such as production of HLA antibodies or graft-versus-host disease in susceptible transfusion recipients. Eliminating the immunogenicity of blood products may prove to be of clinical benefit, particularly in patients requiring multiple transfusions in whom allosensitization is common. This study examines a method of pathogen reduction based on ultraviolet light illumination in the presence of riboflavin. In addition to pathogens, WBCs treated with this system are affected and fail to stimulate proliferation of allogeneic peripheral blood mononuclear cells (PBMNCs) in vitro.

STUDY DESIGN AND METHODS

This study sought to determine the mechanisms regulating this loss of immunogenicity. Treated cells were examined for surface expression of a number of molecules involved in activation and adhesion, viability, cell-cell conjugation, and ability to stimulate immune responses in allogeneic PBMNCs.

RESULTS

Compared with untreated controls, ultraviolet (UV)-irradiated antigen-presenting cells showed slightly reduced surface expression of HLA Class II and costimulatory molecules and had more significant reductions in surface expression of a number of adhesion molecules. Furthermore, treated cells had a severe defect in cell-cell conjugation. The observed loss of immunogenicity was nearly complete, with UV-irradiated cells stimulating barely measurable interferon-gamma production and no detectable STAT-3, STAT-5, or CD3-epsilon phosphorylation in allospecific primed T cells.

CONCLUSION

These results suggest that defective cell-cell adhesion prevents UV-irradiated cells from inducing T-cell activation.

Extracorporeal photopheresis: A focus on apoptosis and cytokines

Induction of apoptosis and changes to cytokine secretion patterns have been implicated in the mechanism of action of extracorporeal photopheresis (ECP). Lymphocyte apoptosis is initially detected in significant numbers prior to re-infusion and by 48 h post-ECP the majority of treated lymphocytes are apoptotic. The early apoptosis involves changes to mitochondrial function, reversal of the Bcl-2/Bax ratio and externalisation of phosphatidylserine. Apoptotic lymphocytes, observed from 20 h post-ECP, are associated with enhanced levels of CD95 and Fas-ligand. For cutaneous T cell lymphoma (CTCL), processing of the apoptotic lymphocytes, by suitable antigen presenting cells (APCs), is suggested to induce a clonal cytotoxic response which targets the malignant T cell population. Increased levels of TNFalpha and IFNgamma, observed post-ECP in monocytes and lymphocytes, respectively, are thought to further contribute to the proposed anti-tumour reaction seen in CTCL. However, down-regulation of pro-inflammatory cytokines and enhanced anti-inflammatory responses have been reported following ECP treatment. These immune responses may contribute to the tempering of the inflammatory conditions, such as graft versus host disease, which respond to ECP. Furthermore, untreated monocytes exposed to ECP-treated lymphocytes have also demonstrated a shift in monocyte cytokine-secretory pattern, toward one associated with immune tolerance. Recently, a mechanism of ECP-induced immune tolerance has been linked to the stimulation of the anti-inflammatory cytokines IL10 and TGFbeta by T regulatory cells, following the infusion of ECP-treated CD11c(+) APCs. Ultimately, the multifaceted responses, induced by ECP, may explain the diversity of clinical conditions that benefit.

DNA targeted UVA photosensitization: characterization of an extremely photopotent iodinated minor groove binding DNA ligand

Previous studies have described UVA-induced DNA strand breakage at the binding sites of iodinated DNA minor groove binding bisbenzimidazoles. The DNA breakage, presumably mediated by the carbon-centred ligand radical produced by photodehalogenation, was also shown to be cytotoxic. The earlier studies included a comparison of three ligand isomers, designated ortho-, meta- and para-iodoHoechst, and the efficiency of photo-induction of strand breaks in plasmid DNA proved to be much higher for the ortho-isomer. We have now extended the comparison of the three isomers with respect to photo-induced cytotoxicity in K562 cells. Although the relationship between the extent of nuclear uptake and the concentration of the ligand in the medium was similar for the three isomers, assay of in situ dehalogenation in drug-treated cells indicated that the apparent cross-section for dehalogenation of the ortho-isomer was greater than 5-fold higher than that for the meta- and para-isomers. Also, analysis of clonogenic survival data showed that the dehalogenation event associated with ortho-iodoHoechst was a more efficient mediator of UVA-induced cytotoxicity in K562 cells than that for meta- or para-iodoHoechst. The number of dehalogenation events associated with 50% cell-kill for ortho-iodoHoechst (1.23+/-0.04 x 10(4)) was less than that for the para- (3.92+/-0.29 x 10(4)) and meta- (11.6+/-0.90 x 10(4)) isomers. Thus it is concluded that the photopotency of ortho-iodoHoechst, which is an important feature in the context of its potential use in clinical phototherapy, is due not only to more efficient UVA-mediated dehalogenation of the ligand, but also to greater cytotoxic potency per dehalogenation event.

Extracorporeal Photopheresis Differentially Regulates the Expression of Phosphorylated STAT-1 and STAT-5 in Treated Monocytes and T cells, Respectively

BACKGROUND

Extracorporeal photopheresis (ECP) is effective in conditions with opposing immune etiology. ECP induces an immunomodulatory response through simultaneous monocyte activation and apoptosis induction of lymphocytes. However, ECP is also immunosuppressive, downregulating proinflammatory cytokines. Signal transducers and activators of transcription (STATs) are important mediators of cell-signaling systems, including cytokines. Ultraviolet (UV) immunosuppression is linked to reductions in cytokine-induced STAT phosphorylation.

OBJECTIVE

The aim of this study was to find whether ECP downregulates STAT phosphorylation.

METHODS

Pre- and post-ECP mononuclear cells from cutaneous T-cell lymphoma and chronic graft-versus-host disease patients were stimulated with either IFNbeta, IL2, or IL15. The percentage of IFNbeta-stimulated monocytes positive for phosphorylated STAT-1 (pSTAT-1) and the number of IL2- and IL15-stimulated T cells expressing phosphorylated STAT-5 (pSTAT-5) were determined at 0 and 24 h.

RESULTS

Post-ECP, pSTAT-1 levels in monocytes remained unchanged; however, at 24 h post-ECP the number of T cells expressing pSTAT-5 was reduced.

CONCLUSION

Following ECP, monocytes retain their ability to phosphorylate STAT-1, while pSTAT-5 expression is lost in lymphocytes. This differential effect of ECP may account for the diverse population of diseases that benefit.

Management of the primary cutaneous lymphomas

Cutaneous lymphomas are rare and, although some are a manifestation of systemic lymphoma, the majority arise primarily from the skin. These primary cutaneous lymphomas comprise both T- and B-cell subtypes and represent a wide spectrum of disorders, which at times can be difficult to diagnose and classify. Classical therapeutic strategies include topical corticosteroids, phototherapy, radiotherapy, retinoids, extracorporeal photopheresis, topical chemotherapy, systemic chemotherapy and biological response modifiers. Newer therapies include the synthetic retinoid bexarotene, the immunotoxin conjugate denileukin diftitox, interleukin-12 and monoclonal antibodies such as alemtuzumab and rituximab.

Selective immmunotherapy through extracorporeal photochemotherapy: yesterday, today, and tomorrow

ECP's extensive clinical record, as well as a considerable improvement in the understanding of the mechanism that underlies its efficacy, opens potential novel strategies for the treatment of cancer, GVHD, transplant rejection, and autoimmunity. The low side effect profile of this therapy has made it a more attractive treatment consideration than current conventional chemotherapeutic and immunosuppressive medications. As the mechanism of action of ECP is more fully elucidated and clinical studies are completed, the role of ECP in modern therapeutics of CTCL and other malignancies, as well as in the treatment of other T-cell mediated diseases, will be become clearer.

Extracorporeal photopheresis reduces the number of mononuclear cells that produce pro-inflammatory cytokines, when tested ex-vivo

Extracorporeal photopheresis (ECP) has been shown to be clinically effective in the treatment of many T cell-mediated conditions. ECP's mechanism of action includes the induction of apoptosis and the release of pro-inflammatory cytokines. Recently, we have observed early lymphoid apoptosis, detectable immediately post ECP. We were interested to determine what influence ECP has on pro-inflammatory cytokine secretion at this early pre-infusion stage. Samples from 6 cutaneous T cell lymphoma (CTCL) and 5 graft versus host disease (GvHD) patients were taken pre ECP and immediately post ECP, prior to re-infusion. Following separation, the PBMCs were added to a cell culture medium and stimulated with PMA, Ionomycin, and Brefeldin A for 6 hours. Using flow cytometry, intracellular cytokine expression of IFNgamma and TNFalpha was determined in the T cell population. The monocytes were evaluated for IL6, IFNgamma, IL12, and TNFalpha. For both patient groups, the number of IFNgamma-expressing T cells fell significantly at re-infusion, whilst both T cell- and monocyte-expressing TNFalpha levels were reduced at re-infusion. All other cytokines tested showed no significant change post ECP. For GvHD, pro-inflammatory cytokines have a pathological role. Their down-regulation may have a direct clinical benefit. However, the reduction in the number of IFNgamma- and TNFalpha-expressing mononuclear cells means, at this early stage, it is unlikely that these cytokines assist in the removal of the malignant Th2 cells present in CTCL.

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.

Extracorporeal photochemoimmunotherapy in cutaneous T-cell lymphoma

Extracorporeal photochemotherapy was originally conceived for the treatment of cutaneous T-cell lymphoma (CTCL) and as well as other T-cell mediated diseases. Evidence collected in the past 17 years has demonstrated that this treatment modality can have a very significant effect on the course of a subset of CTCL patients. The evidence available is positive but for a variety of reasons has been controversial within the medical community. A number of very well-designed multi-center trials which have been lacking since the first publication by Edelson et al. are being carried out so that hopefully a number of open questions will be resolved with greater clarity in the coming years. The fact remains that this innovative approach for the treatment of CTCL and T-cell mediated diseases has certainly opened new avenues of therapy and thought in photoimmunology and photomedicine. Clearly the very low side effect profile of this therapy has made it more attractive than the chemotherapeutic and immunosuppressive substances that are presently available or in experimental protocols. If and when the mechanisms of action are fully understood and appropriate studies investigating different treatment schedules and different combination therapies and modifications of its present form are performed the place of photopheresis in the therapeutics of CTCL as well as other T-cell mediated diseases and oncology will be better placed.

Treatment of cutaneous T cell lymphoma with extracorporeal photopheresis induces Fas-ligand expression on treated T cells, but does not suppress the expression of co-stimulatory molecules on monocytes

Following extracorporeal photopheresis (ECP), lymphocytes become apoptotic and upregulate class I MHC antigenic peptides. Conversely, ECP treated monocytes demonstrate activation markers and have an increased avidity for the phagocytosis of apoptotic T cells. Processing of apoptotic T cells by monocytes, following ECP, is thought to induce an immunomodulatory response, which targets untreated, but clonal T cells. Recently we detected apoptotic lymphocytes immediately post ECP. Although enhanced CD95 (Fas) expression has been observed 24 h post ECP, CD95 and Fas-ligand (Fas-L) expression have not been determined at this very early apoptotic stage. Exposure of monocytes to UV has previously suppressed expression of the co-stimulatory molecules required for the presentation of processed antigens to T cells. Our data demonstrate no increase in CD95 or Fas-L expression on T cells tested immediately following ECP. However, the number of T cells expressing Fas-L significantly increased 24 h post ECP (P<0.005). The expression of the co-stimulatory molecules, CD54, CD80 and CD86, remained unaltered on monocytes treated by ECP. Although the mechanism responsible for early induction of lymphocyte apoptosis remains unclear, the later apoptosis involves Fas-L expression. The maintenance of co-stimulatory molecules, on treated monocytes, indicates that they retain the ability to induce an immunomodulatory response.

Photopheresis affects the course of experimental allergic encephalomyelitis in Lewis rat

BACKGROUND/PURPOSE

The mechanism responsible for the beneficial effects of extracorporeal photochemotherapy (ECP) remains unknown. In the rat model of experimental allergic encephalomyelitis (EAE), the transfer of encephalitogenic cells (EAE cells) induces transient passive EAE, followed by resistance to subsequent disease induction through immunization with central nervous system antigens (active EAE).

METHODS

We tested whether ECP exerts its therapeutic effect by inducing an immune response targeted on circulating pathogenic T-lymphocytes, which results from their increased immunogenicity. We compared the potential of untreated versus ECP-treated encephalitogenic cells to transfer passive EAE and protect against active induction of the disease. The UVA irradiation conditions were derived from intensive ECP protocols used in human clinical studies.

RESULTS

Animals receiving untreated cells showed clinical symptoms following cell transfer but not after subsequent immunisation, whereas those receiving ECP-treated cells remained healthy following cell transfer but experienced clinical symptoms after subsequent immunisation. However, these symptoms were less marked than in control naive rats.

CONCLUSION

Under these ECP protocol conditions, ECP-treated cells have no greater active stimulatory potential for the recipient immune system than untreated cells, since they are less effective at triggering the response that causes the resistant state to active EAE. We suggest that intensive ECP protocol may have deleterious effects with a risk of relapses after treatment discontinuation. The search for the irradiation threshold that would inhibit the T-cell pathogenic properties, but retain their ability to educate the immune system, remains a major research challenge.

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

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

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

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

Extracorporeal photochemoimmunotherapy in cutaneous T cell lymphomas

Extracorporeal photochemotherapy (ECP), or photopheresis, is a widely used treatment for cutaneous T cell lymphoma (CTCL) and other T cell-mediated disorders, having been administered in more than 150 centers worldwide more than 200,000 times. Consistent with the theme of this conference--that is, highlighting the potentially most productive investigative avenues for unraveling the mysteries of CTCL in the next decade--ECP has been futuristic since its inception in the early 1980s. In 1988, the treatment was the first FDA-approved selective immunotherapy for any type of cancer. Yet, the mechanism by which it could suppress a clone of CTCL cells or inactivate multiple autoreactive T cell clones in graft-versus-host disease (GVHD) or allograft rejection remained obscure until quite recently. In fact, the scientific principles necessary to begin to comprehend the basis of ECP's efficacy were not available when the treatment was first introduced in 1982. In the intervening years, necessary detailed knowledge of the structure and function of the clonotypic T cell receptors, of class I major histocompatibility complex (MHC) presentation of tumor antigens, of CTCL tumor-specific antigens, of dendritic antigen presenting cell (DC) biology, and of 8-methoxypsoralen immunopharmacology has been attained. Although much remains to be learned, we now appreciate that ECP simultaneously and efficiently induces both apoptosis of disease-causing T cells and conversion of monocytes to functional DCs. By processing and presenting the unique antigenic determinants of pathogenic T cell clones, the DCs can either initiate a clinically relevant anti-CTCL cytotoxic response or suppress the activity of autoreactive T cell clones. This paper will review clinical trials of ECP in CTCL and evolving scientific understanding of ECP's mechanism in the context of exciting future directions.

Extracorporeal photopheresis in Sézary syndrome: hematologic parameters as predictors of response

Data were analyzed from 23 patients with Sézary syndrome (defined by erythroderma, more than 10% circulating atypical mononuclear cells, and peripheral blood T-cell clone) undergoing monthly extracorporeal photopheresis as the sole therapy for up to 1 year. The cohort showed a significant reduction of skin scores during treatment (P =.001). Thirteen patients (57%) achieved a reduction in skin score greater than 25% from baseline at 3, 6, 9, or 12 months (responders). Reduction in skin score correlated with reduction in the Sézary cell count as a percentage of total white cell count (P =.03). Responders and nonresponders were compared. None of the measured parameters was significantly different between the 2 groups. It was assessed whether any of the baseline parameters predicted outcome. A higher baseline lymphocyte count was significantly associated with a decrease in skin score at 6 months (P <.05). A higher baseline Sézary cell count as a percentage of total white cell count predicted a subject was more likely to be a responder after 6 months of treatment (P =.021). No other parameters predicted responder status. These data show that the modest falls in CD4, CD8, and Sézary cell counts were seen in all patients and might have resulted from lymphocyte apoptosis. This mechanism could explain the more favorable response seen in patients with higher percentages of Sézary cells in the peripheral blood. Alternatively, minimum tumor burden might be required for the induction of a cytotoxic response. Analysis of tumor-specific cytotoxic T cells is needed to investigate these possibilities further.

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.

Treatment of stage II cutaneous T-cell lymphoma with interferon alfa-2a and extracorporeal photochemotherapy: a prospective controlled trial

BACKGROUND

Both interferon alpha and extracorporeal photochemotherapy have been shown to be effective in primary cutaneous T-cell lymphomas (CTCLs). However, no prospective trial has been published on the combination of both treatments, although retrospective investigations suggested a better efficacy than for either interferon or extracorporeal photochemotherapy.

OBJECTIVE

Our purpose was to evaluate the efficacy and toxicity of combined interferon alfa-2a with extracorporeal photochemotherapy in a prospective controlled trial.

METHODS

A prospective controlled study was performed. Fourteen patients (all male) aged 38 to 72 years with CTCL of the mycosis fungoides type, stage IIa/IIb, and a 72-year-old male patient with a Ki-1 lymphoma were treated twice a month for 6 months with extracorporeal photochemotherapy using oral 8-methoxypsoralen as photosensitizer in combination with interferon alfa-2a subcutaneously 3 times a week in the maximal tolerable dosage (ie, up to 18 x 10(6) U). The effects were investigated by a skin score, staging, histologic score (density of the T-cell infiltrate; from 0 = absent to 3 = heavy), immunohistology, and laboratory investigations including total peripheral T-cell count, CD4/CD8 ratio, and soluble interleukin 2 receptor (sIL-2R).

RESULTS

After 6 months, best response was a complete response (CR) in 4 patients, a partial response (PR) in 3, and a stable disease (SD) in 7 of 14 patients (overall response rate [CR + PR] 50%). In responders the time to best response was 4.3 +/- 1.4 months. The skin score decreased from 22.5 +/- 8.1 to 15.1 +/- 11.0 (P <.001), the histologic score decreased from 2.57 +/- 0.51 to 1.21 +/- 0.80 (P <.001). In the lesional skin the percentage of CD4 cells decreased from 75% to 51% (P =.038) and Ki-67-positive cells decreased from 6.7% to 2.4% (P =.001). The total T-cell count/microL decreased from 1018.9 +/- 557.1 to 667.9 +/- 417.9 (P =.012), and the CD4/CD8 ratio also decreased from 1.88 +/- 0.92 to 1.51 +/- 0.67 (P =.038). The sIL-2R levels did not change significantly during the first 4 months of treatment. Among patients of stage IIa the response rate was 60% in contrast to only 25% of those in stage IIb. Side effects were seen temporarily, ranging from grade 0 to grade 3. There was no need for additional therapy, but interferon dose was decreased because of side effects. After 1 year of follow-up the total response rate was 46.2% (6 of 13 patients): 5 of 9 with stage IIa(55.6%) and 1 of 4 with stage IIb (25.0%).

CONCLUSION

These results indicate that patients with CTCL stage IIa can achieve a total response rate of 56% with combined interferon alfa-2a and extracorporeal photochemotherapy. Responders seem to experience their best response within the first 6 months of treatment. The treatment is well tolerated and does not cause severe side effects.

A sensitive gas chromatography-mass spectrometry assay reveals increased levels of monohydroxyeicosatetraenoic acid isomers in human plasma after extracorporeal photoimmunotherapy and under in vitro ultraviolet A exposure

Extracorporeal photoimmunotherapy (photopheresis) is a highly effective therapy in the treatment of various disorders. Although extracorporeal photoimmunotherapy has been successfully used for more than 10 y, its mechanism of action is still unclear. The formation of reactive oxygen species have been implicated in extracorporeal photoimmunotherapy, but malonyl dialdehyde as a marker of systemic lipid peroxidation did not increase significantly during treatment. To investigate further the involvement of reactive oxygen species in extracorporeal photoimmunotherapy, we have introduced a highly sensitive negative ion gas chromatography-mass spectrometry based method for quantitating oxygenated arachidonic acid isomers (hydroxyeicosatetraenoic acids) in plasma samples of patients treated with extracorporeal photoimmunotherapy. In the plasma of healthy volunteers pmole amounts of 2-, 3-, 5-, 8-12-, and 15-hydroxyeicosatetraenoic acid were detected and we observed a dose-dependent augmentation in these metabolites when the blood was irradiated with increasing doses of ultraviolet A in the presence of the photosensitizer 8-methoxypsoralen. Analysis of plasma samples obtained from patients before and after extracorporeal photoimmunotherapy revealed a characteristic increase in total hydroxyeicosatetraenoic acid levels, particularly of 5-hydroxyeicosatetraenoic acid which contributed 80% to the sum of all hydroxyeicosatetraenoic acid isomers. Chiral phase high-performance liquid chromatography indicated almost equal amounts of 5S- and 5R-hydroxyeicosatetraenoic acid suggesting that the majority of lipid peroxidation products are formed via nonenzymatic oxidation reactions.

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.

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.

Extracorporeal photopheresis in cutaneous T-cell lymphoma. Inconsistent data underline the need for randomized studies

Edelson et al.7 first reported the use of extracorporeal photopheresis (ECP) to treat cutaneous T-cell lymphoma (CTCL) in 1987, and since then several studies reporting response rates and survival data have appeared in the literature. Several modes of action have been proposed for ECP. In CTCL there is an accumulating body of evidence to show that 8-methoxypsoralen-treated cells display increased quantities of antigenic peptides at their cell surfaces, and this in turn leads to an enhanced cytotoxic response against the neoplastic T-cell population. This mechanism requires the presence of malignant cells in the peripheral circulation, and may account for the observation that ECP produces higher response rates in erythrodermic CTCL than at other stages of disease. However, patients with inflammatory skin diseases such as reactive erythroderma may also respond to ECP, and it is therefore crucial that a diagnosis of Sézary syndrome is confirmed by demonstrating a clonal population of T cells in the peripheral blood. Unfortunately, most studies have not employed T-cell receptor gene analysis routinely, and this may account for the different response rates and survival data reported with ECP in the literature. To date, ECP has not been tested in a randomized study against conventional forms of therapy.