Mechanisms of lymphocytotoxicity induced by extracorporeal photochemotherapy for cutaneous T cell lymphoma

Extracorporeal photopheresis as an immunomodulatory treatment modality for chronic GvHD and the importance of emerging biomarkers

Haematopoietic stem cell transplantation (HSCT) is the treatment of choice for malignant haematological diseases. Despite continuous improvements in pre- and post-transplantation procedures, the applicability of allo-HSCT is limited by life-threatening complications such as graft-versus-host disease (GvHD), engraftment failure, and opportunistic infections. Extracorporeal photopheresis (ECP) is used to treat steroid resistant GvHD with significant success. However, the molecular mechanisms driving its immunomodulatory action, whilst preserving immune function, require further understanding. As ECP is safe to administer with few significant adverse effects, it has the potential for earlier use in the post-HSCT treatment of GvHD. Thus, further understanding the immunomodulatory mechanisms of ECP action may justify more timely use in clinical practice, as well as identify biomarkers for using ECP as first line or pre-emptive GvHD therapy. This review aims to discuss technical aspects and response to ECP, review ECP as an immunomodulatory treatment modality for chronic GvHD including the effect on regulatory T cells and circulating vs. tissue-resident immune cells and consider the importance of emerging biomarkers for ECP response.

Efficacy of Extracorporeal Photopheresis in Patients With Bronchiolitis Obliterans Syndrome After Lung Transplantation

BACKGROUND

Lung transplantation (LT) is only therapeutic option for patients affected by chronic respiratory failure. Chronic rejection, also known as bronchiolitis obliterans syndrome (BOS), is still the main cause of death and the most important factor that influences post-transplantation quality of life. Currently available therapies have not been proven to result in significant benefit in the prevention or treatment of BOS. Extracorporeal photopheresis (ECP) seems to reduce the rate of lung function decline in transplant recipients with progressive BOS.

METHODS

From 1991 until now, 239 LTs were performed at our center. Fifty-four patients (22.5%) developed BOS; 15 of these (27.7%) were treated with ECP. At the beginning of the treatment, all patients showed a mean decline of forced expiratory volume in 1 second (FEV₁) from baseline values of 45.8% ± 17.2%; 2 patients were in long-term oxygen therapy.

RESULTS

Mean follow-up from November 2013 to June 2016 was 11.6 ± 7 months. Twelve patients (80%) showed lung function stabilization with an FEV₁ range after treatment between -6% to +8% from the pre-treatment values. We did not report any adverse effects or increase of infections incidence.

DISCUSSION

ECP seems to be an effective and well-tolerated therapeutic option for LT patients with BOS in terms of stabilization of lung function and increased survival.

Treatment of Pediatric Acute Graft-versus-Host Disease-Lessons from Primary Immunodeficiency?

Allogeneic hematopoietic stem cell transplant (HSCT) is used to treat increasing numbers of malignant and non-malignant disorders. Despite significant advances in improved human leukocyte antigens-typing techniques, less toxic conditioning regimens and better supportive care, resulting in improved clinical outcomes, acute graft-versus-host disease (aGvHD) continues to be a major obstacle and, although it principally involves the skin, gastrointestinal tract, and liver, the thymus is also a primary target. An important aim following HSCT is to achieve complete and durable immunoreconstitution with a diverse T-cell receptor (TCR) repertoire to recognize a broad range of pathogens providing adequate long-term adaptive T-lymphocyte immunity, essential to reduce the risk of infection, disease relapse, and secondary malignancies. Reconstitution of adaptive T-lymphocyte immunity is a lengthy and complex process which requires a functioning and structurally intact thymus responsible for the production of new naïve T-lymphocytes with a broad TCR repertoire. Damage to the thymic microenvironment, secondary to aGvHD and the effect of corticosteroid treatment, disturbs normal signaling required for thymocyte development, resulting in impaired T-lymphopoiesis and reduced thymic export. Primary immunodeficiencies, in which failure of central or peripheral tolerance is a major feature, because of intrinsic defects in hematopoietic stem cells leading to abnormal T-lymphocyte development, or defects in thymic stroma, can give insights into critical processes important for recovery from aGvHD. Extracorporeal photopheresis is a potential alternative therapy for aGvHD, which acts in an immunomodulatory fashion, through the generation of regulatory T-lymphocytes (Tregs), alteration of cytokine patterns and modulation of dendritic cells. Promoting normal central and peripheral immune tolerance, with selective downregulation of immune stimulation, could reduce aGvHD, and enable a reduction in other immunosuppression, facilitating thymic recovery, restoration of normal T-lymphocyte ontogeny, and complete immunoreconstitution with improved clinical outcome as the ability to fight infections improves and risk of secondary malignancy or relapse diminishes.

Extracorporeal photopheresis in the treatment of graft-versus-host disease: evidence and opinion

Despite significant advances in prevention and treatment strategies, graft-versus-host disease remains the most significant cause of morbidity and nonrelapse mortality after allogeneic hematopoietic cellular transplantation. Corticosteroids remain the standard frontline therapy for graft-versus-host disease; however, a considerable number of patients will not respond adequately and others will be significantly affected by adverse effects. Extracorporeal photopheresis is one of several secondary therapies which have shown promise in the clinical setting. While the procedure itself has been around for over 20 years, our understanding of the mechanisms from which therapeutic benefits are seen, and the population they are seen in, remains limited. In this article, we review the use of extracorporeal photopheresis for the treatment of graft-versus-host disease including details covering the procedure's mechanism of action, safety profile and clinical efficacy data.

A prospective interventional study on the use of extracorporeal photopheresis in patients with bronchiolitis obliterans syndrome after lung transplantation

BACKGROUND

The aim of this prospective study was to evaluate the efficacy and safety of extracorporeal photopheresis (ECP) in patients with bronchiolitis obliterans syndrome (BOS) after lung transplantation and to identify factors predicting treatment response.

METHODS

The study was performed at a single center and consisted of a cohort of 1,012 lung transplant recipients (November 1989-June 2010). A total of 194 patients developed BOS after a mean of 1,293 ± 1,008 days (range, 99-4,949 days) and received established treatment, and 51 patients received additional ECP.

RESULTS

Thirty-one (61%) of the ECP-treated patients responded to the therapy and showed sustained stabilization (forced expiratory volume in 1 second range, -5% to 5% vs baseline at start of ECP) of lung function over 6 months. Responders to ECP showed significantly greater survival and less need for retransplantation (p = 0.001) than non-responders. Factors associated with an inferior treatment response were cystic fibrosis as underlying lung disease and a longer time between transplantation and development of BOS. No side effects were observed after ECP. Compared with BOS patients not treated with ECP, the ECP responders showed an improved graft survival (p = 0.05).

CONCLUSIONS

These results confirm and suggest that early use of ECP could be an effective adjunct treatment for patients who develop BOS after lung transplantation.

Extracorporeal photopheresis as a curative treatment strategy in non epidermotropic T-cell lymphoma and large granular lymphocyte leukemia

BACKGROUND

To evaluate the efficacy of extracorporeal photopheresis (ECP) in noncutaneous T-cell lymphoma and large granular lymphocytes leukemia (LGL).

PATIENTS AND METHODS

We have treated 12 refractory/relapsed patients. Six peripheral T-cell lymphoma (PTCL), one T-lymphoblastic lymphoma and five LGL with blood involvement received six biweekly leukapheresis as induction phase, followed by one course a week for 4 weeks as consolidation and one course of maintenance per month for responders until progression/relapse or disappearance of the peripheral clone.

RESULTS

Six patients responded to phototherapy. Two PTCL and two LGL achieved a complete response (CR) and two other PTCL a partial response. The median duration of CR was 117 months (45-150 months) for these four patients. The peripheral clone followed by flow cytometry decreased in all six responders. Two patients with a complete disappearance of the peripheral clone have not relapsed.

CONCLUSIONS

As for cutaneous T-cell lymphoma, ECP therefore to be efficient for PTCL and LGL. Early decrease and disappearance of the peripheral clone were the indicators of clinical response and nonrelapse, respectively.

Follow-up of the T-cell clonality in Sezary patients treated by extracorporeal photopheresis using a new assay: the immunoscope technique

Sezary syndrome is a leukemic form of epidermotropic cutaneous T-cell lymphoma related to the malignant proliferation of clonal CD4+ T-cells. Extracorporeal photochemotherapy (ECP) may induce a transient improvement of the clinical signs but it's efficiency is discussed. In order to investigate the T-cell clonality in the peripheral blood of patients with Sezary syndrome and to monitor its evolution in 8 patients treated by ECP, we used the Immunoscope technique. In one patient, we observed a decrease of the T-cell clonality from 15.6% to 0%, paralleling a complete remission of the clinical disease with a disappearance of the circulating Sezary cells. In the other cases, the evolution of the relative frequency paralleled the clinical status of the patient. In 3 cases, we observed a quick-acting direct cytotoxicity of the association 8MOP + UVA on the T-cell clone present in the cellular product. Immunoscope technique appears to be an efficient assay to appreciate the amount of tumoral cells and monitor the evolution of the clonal component in Sezary syndrome.

Adhesion of MNC to extracellular matrix proteins following in vitro photochemotherapy

BACKGROUND

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

METHODS

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

RESULTS

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

DISCUSSION

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

Apoptosis in leukocytes induced by UVA in the presence of 8-methoxypsoralen, chlorpromazine or 4,6,4'-trimethylangelicin

Although 8-methoxypsoralen (8-MOP) has been successfully used in extracorporeal photochemotherapy (ECP) of several T cell-mediated diseases, the exact mechanism of the drug therapeutic action has not been established. We have studied in vitro apoptotic activity of 8-MOP, and for comparison of 4,6,4'-trimethylangelicin (TMA) and chlorpromazine (CPZ) as alternative photosensitizers for potential use in photopheresis. However, while 8-MOP and CPZ are known for their immune suppressive activity, TMA does not exhibit such an activity in an animal model for ECP. Apoptosis and necrosis were measured in both Jurkat cells and primary rat leukocytes under conditions comparable to those used in the animal model to suppress contact hypersensitivity (CHS). Cells were irradiated with UVA (200 kJ/m(2)) after treatment with 8-MOP, CPZ or TMA (300 ng/ml). Flow cytometric analysis (annexin-V-FLUOS/propidium iodide) and fluorescence microscopy examinations, using acridine orange/propidium iodide, indicated that the number of cells undergoing apoptosis or necrosis increased significantly after 24 h following treatment. Similar results were observed irrespective of the cell type and photosensitizer used. The results of the present study, combined with previous observations with the animal model for ECP, suggest that apoptosis is not likely to be a critical step in the cascade of events leading to immunosuppression.

A prospective study on the evolution of the T-cell repertoire in patients with Sézary syndrome treated by extracorporeal photopheresis

Sézary syndrome is a leukemic form of epidermotropic cutaneous T-cell lymphoma related to the malignant proliferation of clonal CD4+ T cells. Extracorporeal photochemotherapy may induce a transient improvement of the clinical signs, but its efficiency is discussed. To investigate the frequency of the T-cell clone in the peripheral blood of patients with Sézary syndrome and to monitor its evolution in patients treated using extracorporeal photopheresis or chemotherapy, we used the immunoscope technique. In one patient, we observed a decrease of the relative frequency of the clone from 15.6% to 0%, paralleling a complete remission of the clinical disease and a disappearance of the circulating Sézary cells. In the other cases, the evolution of the relative frequency paralleled the initial improvement of the clinical status and the absence of long-term efficiency in patients treated with extracorporeal photopheresis or chemotherapy. We observed a quick-acting direct cytotoxicity of the association 8MOP + UVA on the T-cell clone. The immunoscope technique appears to be an efficient tool to appreciate the amount of tumoral cells and to monitor the evolution of the clonal component in the Sézary syndrome.

A prospective study on the evolution of the T-cell repertoire in patients with Sézary syndrome treated by extracorporeal photopheresis

Sézary syndrome is a leukemic form of epidermotropic cutaneous T-cell lymphoma related to the malignant proliferation of clonal CD4+ T cells. Extracorporeal photochemotherapy may induce a transient improvement of the clinical signs, but its efficiency is discussed. To investigate the frequency of the T-cell clone in the peripheral blood of patients with Sézary syndrome and to monitor its evolution in patients treated using extracorporeal photopheresis or chemotherapy, we used the immunoscope technique. In one patient, we observed a decrease of the relative frequency of the clone from 15.6% to 0%, paralleling a complete remission of the clinical disease and a disappearance of the circulating Sézary cells. In the other cases, the evolution of the relative frequency paralleled the initial improvement of the clinical status and the absence of long-term efficiency in patients treated with extracorporeal photopheresis or chemotherapy. We observed a quick-acting direct cytotoxicity of the association 8MOP + UVA on the T-cell clone. The immunoscope technique appears to be an efficient tool to appreciate the amount of tumoral cells and to monitor the evolution of the clonal component in the Sézary syndrome.

Effect of insulin-dependent diabetes mellitus on response to extracorporeal photopheresis in patients with Sézary syndrome

BACKGROUND

Extracorporeal photopheresis (ECP) has become a primary therapy for selected forms of cutaneous T-cell lymphoma, especially Sézary syndrome. Variability in response of patients with Sézary syndrome to ECP has been reported.

OBJECTIVE

Our purpose was to determine whether underlying medical conditions influence the efficacy of ECP in patients with Sézary syndrome.

METHODS

We retrospectively reviewed the medical records of 55 patients with Sézary syndrome who received ECP between 1987 and 2000. Efficacy criteria included decrease in Sézary cell count, erythroderma, lymphadenopathy, organomegaly, and pruritus.

RESULTS

Thirty-four patients responded well and 10 patients responded partially to ECP; 11 patients had no response. Nine patients with no response to ECP had insulin-dependent diabetes mellitus (IDDM). IDDM was documented in only 2 patients with a good response and in no patients with a partial response to ECP.

CONCLUSION

Patients with Sézary syndrome and IDDM typically respond poorly to the standard ECP treatment regimen.

Expression of apoptosis markers on peripheral blood lymphocytes from patients with cutaneous T-cell lymphoma during extracorporeal photochemotherapy

The mechanisms of extracorporeal photochemotherapy (ExP) therapeutic activity in cutaneous T-cell lymphomas (CTCLs) are not yet well understood, even though it has been suggested that a major mechanism may be induction of apoptosis. In vitro studies demonstrate that UVA-induced apoptosis is mediated by CD95-Fas expression and inhibited by Bcl-2 up-regulation and that UVA irradiation is able to down-regulate Bcl-2 expression. High-resolution multiparameter flow-cytometric analyses were used to evaluate Bcl-2/CD95-Fas expression on phenotypically identifiable circulating clonal T cells from 7 patients with CTCL (4 with Sézary syndrome and 3 with mycosis fungoides with peripheral involvement) before and during ExP, in an attempt to ascertain whether Bcl-2/CD95-Fas status can be related to the hematologic response. A Bcl-2 normal phenotype before ExP or a normalization in Bcl-2 expression during ExP were related to a better clinical response, whereas a persistent Bcl-2 high expression was a negative prognostic factor. On the other hand, no response was found in patients with a CD95-Fas-negative phenotype, whereas the expression of CD95-Fas was associated with hematologic remission. Although further studies are needed to confirm these preliminary results, this study suggests that Bcl-2 and CD95-Fas expression could be evaluated, together with the other known clinical and immunologic factors, as additional parameters related to clinical response in patients with CTCL undergoing ExP.

Treatment of cutaneous T-cell lymphomas

Primary cutaneous T-cell lymphomas (CTCL), representing a heterogeneous group of non-Hodgkin's lymphomas (NHL), can be defined as clonal proliferation of skin-infiltrating T lymphocytes primarily presenting in the cutaneous compartment. They show a considerable variation in clinical presentation, histology, immunophenotype, and prognosis, which is best reflected by the proposal of the Cutaneous Lymphoma Study Group of the European Organization for Research and Treatment of Cancer (EORTC). Due to the heterogeneity of CTCL and the lack of curative therapy regimens, multiple strategies have been proposed for the management of the different CTCL entities. This includes topical application of corticosteroids, nitrogen mustard or carmustine (BCNU), radiotherapy, including total skin electron beam irradiation, photo(chemo)therapy, biological response modifiers, cytostatic chemotherapy, and combined regimens. More recently, fusion proteins and peptide vaccines have been introduced in the management of CTCL. Classification, staging, and treatment modalities are discussed in detail and summarized in a stage-adapted therapy regimen for CTCL.

Durable loss of a malignant T-cell clone in a stage IV cutaneous T-cell lymphoma patient treated with high-dose interferon and photopheresis

Stage IV cutaneous T-cell lymphoma (CTCL) has a notoriously poor prognosis and many treatment options exist. We describe the successful treatment of a case of stage IV CTCL with combination photopheresis and high-dose interferon alfa (IFNalpha). The patient was treated with combination therapy of monthly photopheresis and daily doses of IFNalpha up to 36 MU. Response to therapy was followed by clinical observation and Southern blot analysis for the detection of a malignant clone. The findings of this case were compared with others using a computer-based literature review. A complete clinical response lasting 64 months was achieved. Clinical relapse was preceded by an increase in the CD4/CD8 ratio and by reappearance of the T-cell receptor gene rearrangement. Combined photopheresis and high-dose IFNalpha led to a durable and sustained complete response in stage IV CTCL. CD4/CD8 ratios and T-cell gene rearrangements may be helpful in patient management.

Extracorporeal photochemotherapy for cutaneous T-cell lymphoma: a 9.7-year experience

Cutaneous T-cell lymphoma (CTCL) is an indolent lymphoma usually of CD4+ T lymphocytes in which the aggressive treatment for the advanced stages does not increase survival. Photopheresis has been established as an alternative modality for the therapy of erythrodermic CTCL and reportedly improves survival in patients with advanced stages of the disease. The objective of this study is to review the experience of treating patients with erythrodermic CTCL with extracorporeal photochemotherapy (ECP) at the New York Veteran Affairs Medical Center/NYU Medical Center between September 1987 and April 1997. Forty-one patients with erythrodermic CTCL (stages III and IV) received photopheresis; 25 of them fulfilled the inclusion criterion, i.e., the completion of greater than or equal to 6 cycles of photopheresis. Skin score was defined as a product of severity and percentage of involved surface area. Complete clinical response was defined as disappearance of measurable disease for at least one month, and partial response was defined as greater than or equal to 50% clearance of measurable disease for at least one month. The profile of the patients was: 20 men, 5 women; average age: 64.2 years; 17 patients had stage III disease, and 8 had stage IV disease. Five of the 25 patients (20%) achieved complete clinical response, another 15 (60%) had partial response, and 5 (20%) had no response. The mean time (+/- SD) to achieve complete clinical clearance was 12.6 +/- 10 months (range: 4-30 months) and the mean time (+/- SD) to obtain partial clinical response, including complete response, was 9.7 +/- 5.3 months (range: 4-17 months). Remission duration ranged from 9 to 67 months. The median survival time from the time of initiation of photopheresis is estimated at 70 months. The complete responder group had a lower median CD4/CD8 ratio compared to the non-responders at baseline (3.8 vs 7.2, respectively), although the difference was not statistically significant (P = 0.40). At the time of maximal response, the CD4/CD8 ratio of the complete responder group decreased towards normal values (median = 1.2), whereas this ratio increased among the non-responders (median = 11.0; P = 0.04). Side effects were minimal. Extracorporeal photochemotherapy is an effective and safe treatment for erythrodermic CTCL. In some of these patients, it can induce a long-term and complete clinical remission.

Extracorporeal photochemotherapy (photopheresis) induces apoptosis in lymphocytes: a possible mechanism of action of PUVA therapy

The mechanism of action of psoralen plus UVA (PUVA) and photopheresis is not entirely understood. These therapies are assumed to be immunomodulating partly by gradually decreasing leukocyte viability. We investigated whether this delayed form of cell death was due to apoptosis. Untreated and treated (PUVA exposed) leukocytes obtained from six patients with systemic sclerosis and (untreated) leukocytes from healthy control individuals were studied. Qualitative gel electrophoresis and quantitative in situ nick translation analysis of DNA fragmentation was performed. Apoptosis of the treated cells did occur (gel electrophoresis) after 24 h. At t = 0 h, immediately after exposure to PUVA, there was no evidence of DNA fragmentation in the treated cells. The percentage of treated cells undergoing apoptosis was 20-55% at t = 24 h (in situ nick translation). The untreated leukocytes of the patients and the healthy individuals showed no distinctive rise in apoptotic cells. Apoptosis of the leukocytes after PUVA or photopheresis treatment might be a mechanism of action and might explain the therapeutic response.

Photopheresis therapy for cutaneous T-cell lymphoma

BACKGROUND

Cutaneous T-cell lymphoma is a chronic peripheral lymphoma in which aggressive combined therapy elicits high response rates but does not improve survival. Photopheresis therapy has reportedly induced remissions and prolonged survival in patients with advanced disease.

OBJECTIVE

We studied all patients who began photopheresis treatment between February 1988 and July 1994 to determine whether we could confirm the remission rates of previous studies, to evaluate variables that might predict a response, and to discover whether an accelerated delivery system would improve the remission rate or response time.

METHODS

After an oral dose of methoxsalen was administered, a leukocyte-enhanced quantity of blood was exposed to UVA radiation for 1.5 hours and returned to the patient. With our accelerated system, 6 x 10(9) cells were irradiated in nine cycles. Treatments were given on 2 consecutive days once a month.

RESULTS

Among 34 patients whose results could be evaluated, the overall response rate (complete and partial remissions) was 50%; most patients had mild side effects. All responders except one had erythroderma. Responders had a decrease of 75% in mean skin scores, whereas nonresponders had an increase of 21%.

CONCLUSION

Photopheresis appears to be effective for selected patients with erythrodermic cutaneous T-cell lymphoma, although we did not achieve as high a remission rate as previously reported by others.

Apoptosis induction of ultraviolet light A and photochemotherapy in cutaneous T-cell Lymphoma: relevance to mechanism of therapeutic action

The anti-tumor action of many chemotherapeutic agents has recently been attributed to the induction of apoptosis in the malignant cell population. In this study, we investigated the ability of extracorporeal photopheresis (ExP) and in vitro PUVA (8-methoxy-psoralen + ultraviolet A) therapy to induce apoptosis in peripheral blood mononuclear cells from Sezary syndrome patients and normal controls. Flow cytometric analysis of ExP- or PUVA-treated peripheral blood lymphocytes demonstrated two distinct cell populations within 24 h of treatment. One population was similar to untreated controls with the other exhibiting characteristics of apoptotic cell death, i.e., a loss of cell volume and an accompanying increase in cell density. This latter population was comprised of cells with DNA strand breaks as determined by the Tdt-mediated deoxyuridine triphosphate-biotin nick end labeling assay. Apoptosis was also confirmed morphologically by fluorescent and electron microscopy as well as by demonstration of characteristic DNA strand breaks (laddering) using gel electrophoresis. Apoptosis was not observed with 8-methoxypsoralen (< or = 300 ng per ml) alone; however, ultraviolet A alone at doses > or = 2 J per cm2 induced apoptosis in lymphocytes. Peripheral blood T-cell subpopulations of Sezary syndrome patients, including the malignant clone, were equally susceptible to apoptosis subsequent to either photopheresis or PUVA treatment. In contrast, monocytes (CD14+/CD45+) appear to be resistant to apoptosis induction by ExP or PUVA treatment. Moreover, ExP-treated and untreated monocytes phagocytized apoptotic, but not untreated, peripheral blood mononuclear cells. ExP and PUVA have been shown to be efficacious and well-tolerated therapies in the treatment of dermatologic diseases and transplant rejection. These data suggest that induction of apoptosis may be an important event for therapeutic efficacy.

Kinetic analysis of apoptosis induction in human cell lines by UVA and 8-MOP

Whereas previous studies have indicated that DNA damage as a result of 8-methoxypsoralen (8-MOP) and UVA treatment leads to cell death, this study establishes the minimum concentrations of 8-MOP and UVA necessary to induce apoptosis in human T-lymphocytic and monocytic cell lines. In order to asses apoptosis, we used fluorescent microscopy to examine changes in light scattering as well as internucleosomal DNA fragmentation. Generation of a dose response curve showed that the minimum combination of UVA and 8-MOP that was necessary to induce greater than background levels of apoptosis within 24 h of treatment was 0.5 J/cm2 UVA and 12.5 ng/mL of 8-MOP. A striking observation was that UVA alone at doses > or = 1.0 J/cm2, but not 8-MOP alone (0-300 ng/mL), induced significant apoptosis in the Sup-T1 cells induced by UVA alone was not as great as that of 8-MOP and UVA in combination, a highly significant correlation between the product of the concentration of 8-MOP (ng/mL) times the dose of UVA (J/cm2) and the percentage of apoptotic cells was observed. This correlation provides an important tool for studying the relationship of UVA-induced DNA damage to apoptosis induction. moreover, it will provide a means by which early events in the apoptotic pathway can be dissected.

Inhibition of cardiolipin biosynthesis in the hypoxic rat heart

Cardiolipin is the principal polyglycerophospholipid in the heart. The effect of hypoxia on cardiolipin biosynthesis was investigated in isolated rat hearts perfused in the Langendorff mode. Hearts were pulsed-labeled for 60 min with 0.1 mM [1,(3)-3H]glycerol in Krebs Henseleit buffer saturated with either 95% O2/5% CO2 (control) or 95% N2/5% CO2 (hypoxic). Radioactivity incorporated into phosphatidylglycerol and cardiolipin were reduced 88% (P < .05) and 79% (P < .05), respectively, in hypoxic hearts compared to controls. In other experiments, hearts were pulse-labeled for 15 min with 1.4 mM [32P]Pi in Krebs Henseleit buffer saturated with 95% O2/5% CO2 and subsequently perfused for 60 min under control or hypoxic conditions. The radioactivity incorporated into CDP-1,2-diacyl-sn-glycerol, phosphatidylglycerol, and cardiolipin were reduced 61% (P < .05), 71% (P < .05), and 70% (P < .05), respectively, in the hypoxic hearts compared to controls, indicating a decreased formation of CDP-1,2-diacyl-sn-glycerol in the hypoxic heart. The activities of the enzymes involved in cardiolipin biosynthesis and the cardiac pool sizes of cardiolipin, phosphatidylglycerol, and CDP-1,2-diacyl-1,2-diacyl-sn-glycerol were unaltered between hypoxic and control hearts. In contrast, cardiac adenosine-5'-triphosphate and CPT levels were decreased 94% (P < .05) and 92% (P < .05), respectively, in hypoxic hearts compared to controls. We postulate that the biosynthesis of the cardiac polyglycerophospholipid cardiolipin may be inhibited by a decreased adenosine-5'-triphosphate and cytidine-5'-triphosphate level in the heart.

Extracorporeal photopheresis--a new approach for the treatment of cutaneous T cell lymphomas

Extracorporeal photochemotherapy (extracorporeal photopheresis, ECP) is going to become a new alternative in the treatment of cutaneous T cell lymphomas (CTCL), autoimmune disorders, and transplant rejections. After the first promising results in the treatment of CTCL reported in 1987 by Edelson et al. increasing numbers of CTCL patients in a growing number of ECP centers throughout the United States, Europe, and Japan have been successfully treated. Today, it seems that in particular Sézary's syndrome and the erythrodermic variant of mycosis fungoides (MF) respond very well to ECP. Compared to historical controls of MF with lymph node involvement, the median survival of the ECP-treated patients increased from 30 months to up to 60 months. It is our experience that the tumor stage of MF, however, cannot be treated with ECP alone, but is successfully controlled by combination regimens, for example with recombinant interferon alpha. CTCL patients heavily pretreated by polychemotherapy and severe endogenous or iatrogenic immunsuppression do not respond sufficiently and are not good candidates for ECP. The adverse reactions under ECP are well controlled and very low in number. In particular, general immunosuppression by ECP has not been reported so far.

Relaxation of supercoiled DNA by aminomethyl trimethylpsoralen and UV photons: action spectrum

An action spectrum for the relaxation of supercoiled plasmid DNA (induction of the first single-strand break) by photoactivated 4'-aminomethyl-4,5',8-trimethylpsoralen (AMT) has been determined using monochromatic UV photons from 254 to 405 nm. The spectrum of AMT-induced plasmid DNA relaxation fits closely with the absorbance spectrum of AMT in the spectral region between 313 nm and 405 nm but deviates at wavelengths shorter than 313 nm. This assay also reveals that the psoralen photosensitization reaction with DNA also produces piperidine-labile sites. Addition of mannitol and azide partially quenches the supercoil relaxation reaction, evidence for a role of Type II photosensitization pathway.

Therapeutic alternatives in cutaneous T-cell lymphoma

Mycosis fungoides and Sézary syndrome, collectively referred to as cutaneous T-cell lymphoma, are non-Hodgkin's lymphomas that initially appear in the skin. Early-stage disease, limited to the skin, is best treated with sequential topical therapies such as topical nitrogen mustard, psoralen phototherapy (PUVA), or total-skin electron beam therapy. Photopheresis is the first line of therapy for the patient with erythroderma. Systemic therapy is generally reserved for patients with refractory disease and patients who initially present with extracutaneous involvement. Although there are several treatment options for cutaneous T-cell lymphoma, there have been few randomized comparative trials.

Photopheresis: a clinically relevant immunobiologic response modifier

Photopheresis, the process by which peripheral blood is exposed in an extracorporeal flow system to photoactivated 8-methoxypsoralen (8-MOP), is an effective new treatment for certain disorders caused by aberrant T lymphocytes. It has become a standard therapy for advanced cutaneous T cell lymphoma and shows promise in the treatment of four autoimmune disorders (pemphigus vulgaris, the progressive systemic sclerosis form of scleroderma, rheumatoid arthritis, systemic lupus erythematosus) and in reversal of immunologic rejection of transplanted organs. Positive immunologic alterations observed in patients with AIDS-related complex merit further investigation, and preliminary trials in the management of patients with multiple sclerosis, myasthenia gravis and autoimmune insulin-dependent diabetes mellitus have recently been initiated. The inability of the treatment to meaningfully alter the course of the B cell malignancy, chronic lymphocytic leukemia, suggests that B cell proliferations, at least those involving malignant cells, may be more resistant to this treatment. The mechanism of action of photopheresis is likely to be multifaceted, but at least in experimental systems appears to involve an immunization against the pathogenic T cells, in a highly specific manner. Photoactivated 8-MOP initiates a cascade of cellular events by forming covalent photoadducts with nuclear DNA, with cell surface molecules and possibly with other cytoplasmic components of the ultraviolet exposed leukocytes. For reasons not yet clear, exposure of populations of T cells containing expanding a clone(s) of pathogenic T cells to photoactivated 8-MOP alters these cells so that their reinfusion induces a therapeutically significant immunologic reaction that targets unirradiated T cells of the same pathogenic clone(s). It is suggested that the specificity of the induced immunologic reaction may result, in sequence, from the exquisitely titratable damage that 8-MOP inflicts upon cells of the pathogenic clone(s), the return of these cells to an immunocompetent individual, the removal of the photo-damaged cells from the blood by the reticuloendothelial system and the preferential induction of an immune response against cells of the pathologically expanded clone(s).

DNA damage, poly (ADP-ribosyl)ation and apoptotic cell death as a potential common pathway of cytotoxic drug action

Although various anti-cancer drugs have widely differing primary modes of action, the mechanisms of cell death appear similar but are not well understood. To investigate this problem we exposed cultured human leukemic T-lymphoblasts to 1-hr pulse doses of an alkylating agent (mafosfamide) and a topoisomerase II inhibitor (etoposide) that cause delayed cell death. The effects of these drugs on nucleotide content, poly (ADP-ribosyl)ation and DNA strand breakage were assessed. Both drugs caused DNA strand breakage, and although the pattern differed, this seemed to be the major mechanism by which cells were killed. The degree and time course of the NAD and ATP depletion that mafosfamide and etoposide caused were similar. Both drugs caused a nadir in cellular nucleotide levels 2 hr after exposure but between 2 and 6 hr there was a partial recovery. This correlates with the time course of the DNA damage they caused and appeared to result from poly (ADP-ribosyl)ation. Both drugs were shown to cause apoptotic cell death associated with endonucleolytic DNA fragmentation. We suggest that DNA damage, as a primary or secondary effect, associated with poly (ADP-ribosyl)ation and apoptotic cell death may be a common pathway of cytotoxic drug action.

Prevention of cyclophosphamide-induced and spontaneous diabetes in NOD mice by syngeneic splenocytes treated with cytotoxic drugs

Infusions of syngeneic T-cells, lethally damaged with ultraviolet A light (UVA) and 8-methoxypsoralen (8-MOP), have been reported to prevent or ameliorate a number of autoimmune diseases in humans and in animal models of autoimmune disease. We previously demonstrated that the combination of UVA/8-MOP, or deoxycoformycin and deoxyadenosine (dCF/dAdo), damaged human lymphoid cells by inducing DNA strand breakage and stimulating poly (ADP-ribosyl)ation. These cells subsequently underwent programmed cell death ("apoptosis"). These findings suggested a common mechanism of lymphocyte damage, and that in vitro treatment of T-cells with cCF/dAdo might substitute for UVA/8-MOP. This hypothesis was tested in a model of autoimmune diabetes in the NOD mouse. Young adult female NOD/Wehi mice were given 350 mg/kg cyclophosphamide (CP) on day 1 to induce rapid-onset diabetes and divided into five treatment groups. Four groups received approximately 50 x 10(6) syngeneic mouse splenocytes that had been treated with various cytotoxic agents. 27/40 (68%) of the CP-only control group and 14/30 (48%) of the group given untreated splenocytes developed diabetes. By contrast, only 2/20 (10%) mice of UVA/8-MOP and 3/23 (14%) of dCF/dAdo-treated splenocyte groups developed diabetes (P < 0.01). Diabetes in high spontaneous-diabetes incidence NOD/Lt female mice was also greatly reduced (4/8 untreated vs 1/7 treated; (< 0.05). We postulate that cytotoxic damage to activated splenic T-cells allows their recognition by host T-cells and results in a protective response against autoreactive cells as a form of T-cell vaccination.(ABSTRACT TRUNCATED AT 250 WORDS)