Treatment of T lymphocytes with 8-methoxypsoralen plus ultraviolet A induces transient but biologically active Th1-skewing cytokine production

Chemoirradiated neutrophils and T cells differentially affect immune functions of APCs

Extracorporeal photopheresis (ECP) is known as an immunomodulatory therapy with few side effects, which is mainly used in the treatment of cutaneous T cell lymphoma, graft-versus-host disease, and allograft rejection. During ECP, leukocytes are separated from whole blood by leukapheresis, subsequently chemoirradiated with 8-methoxypsoralen and UVA light, and re-infused into the patient. Although clinically effective, its mode of action has not been fully elucidated. In the present study, we analyzed the interaction of chemoirradiated neutrophils and CD3+ lymphocytes with APC in an in vitro model. We report that chemoirradiated CD3+ T cells induced increased expression of activation markers on dendritic cells (DC), macrophages, and monocytes. Coculture of chemoirradiated CD3+ T cells with these APC also led to significantly increased secretion of TNF-α. Although less pronounced, additional activation of APC took place when APC were stimulated with LPS or IFN-γ. In contrast, chemoirradiated neutrophils did not show activating effects on APC. The presence of chemoirradiated neutrophils during LPS and IFN-γ stimulation of DC rather diminished DC and macrophage activation. In line with these findings DC cocultured with chemoirradiated CD3+ T cells, but not neutrophils, showed significantly increased activation of CD3+ responder lymphocytes in a mixed lymphocyte reaction. With this study, we demonstrate that chemoirradiated leukocytes have differential indirect immunomodulatory effects. Whereas chemoirradiated CD3+ T cells activate APC, chemoirradiated neutrophils suppress activation of APC in the presence of other activating factors, suggesting that the composition of the ECP-treated buffy coat might be of importance for its immunomodulatory effects.

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.

A new device to study ex-vivo the effects of extracorporeal photochemotherapy on the immune system

Extracorporeal photochemotherapy (ECP) is a medical procedure effective in the treatment of several different T-cell mediated diseases such as cutaneous T-cell lymphoma and Graft-versus-Host Disease. During ECP treatment the patient's blood is processed by means of a cell separator to collect leukocytes (leukapheresis), mostly lymphocytes and monocytes, which are then incubated with the photoactive drug 8-methoxypsoralen (8-MOP), exposed to ultraviolet-A light (UV-A) and reinfused to the patient. It has been suggested that during ECP not only UV-A irradiation but also changes in the environmental condition may be relevant. Although ECP has been shown to have an in-vivo immunomodulatory effect, the mechanisms through which ECP exerts its effect remain elusive. One of the reasons for this incomplete knowledge is the absence of a reliable model for ECP. In order to investigate the effect of ECP on the peripheral immune system, we developed a new device which mimics the complete ECP cycle including blood transit through the cell separator. Peripheral blood samples (50ml) were obtained from volunteers and processed using a peristaltic pump. Peripheral blood mononuclear cells (PBMC) were then collected and treated with 8-MOP and UV-A under the same conditions used for the patients' therapy. Using this strategy we investigated 8-MOP, UV-A and their combined effect on the production of the pro-inflammatory cytokines interferon-gamma (IFN-gamma), interleukine-2 (IL-2) and tumor necrosis factor-alpha (TNF-alpha) in PBMC with and without polyclonal stimulation. We firstly demonstrated that our device does not affect total red and white blood cell counts. After 8-MOP and UV-A irradiation a significant decrease was observed in both activated CD4(+) and CD8(+) T lymphocytes producing IFN-gamma, IL-2 and TNF-alpha. Our findings are in line with those previously obtained in humans after complete ECP treatment, thus suggesting that our newly developed device is suitable for investigating the mechanism of action of ECP ex-vivo.

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.

Lymphocytes treated by extracorporeal photopheresis can down-regulate cytokine production in untreated monocytes

BACKGROUND

Pro-inflammatory cytokines are actively involved in graft-versus host-disease (GvHD) aetiology. Treatment of GvHD, using extracorporeal photopheresis (ECP), has demonstrated clinical efficacy. ECP rapidly reduces the number of T cells that produce tumour necrosis factor alpha (TNFalpha), interferon gamma (IFNgamma) and interleukin (IL)2. ECP-treated cells are re-infused immediately after completion of treatment. This study attempted to determine the influence that ECP-treated cells would have on untreated cells following re-infusion.

METHODS

Heparinized samples were taken from 10 chronic GvHD patients, pre-ECP and immediately prior to re-infusion (post-ECP). Lymphocytes and monocytes were isolated using magnetic separation. The post-ECP lymphocytes were mixed with pre-ECP monocytes, while the post-ECP monocytes and pre-ECP lymphocytes were combined. After suitable stimulation, the T cells were tested for intracellular TNFalpha, IFNgamma and IL2, while the monocytes were evaluated for TNFalpha, IL1alpha, IL1beta, IL6 and IL8.

RESULTS

Although cytokine secretion is decreased in T cells exposed to ECP, pre-ECP T cells were unaffected by post-ECP monocytes. Post-ECP monocytes demonstrated a reduction in cytokine secretion. Furthermore, untreated monocytes down-regulated cytokine production following exposure to ECP-treated lymphocytes.

CONCLUSION

ECP has both a direct and indirect immunosuppressive action, both of which may be beneficial in the treatment of GvHD.

Evidence-based practice of photopheresis 1987-2001: a report of a workshop of the British Photodermatology Group and the U.K. Skin Lymphoma Group

Photopheresis or extracorporeal photochemotherapy (ECP) is a novel immunomodulatory therapy which involves separation of the patient's leucocyte-rich plasma, followed by ex vivo administration of a photosensitizer and ultraviolet A radiation, before reinfusion. ECP has been used successfully for the treatment of cutaneous T-cell lymphoma (CTCL: Sézary syndrome), graft-versus-host disease (GVHD) and cardiac transplant rejection. ECP has a dose-sparing effect on concurrent immunosuppressive therapy. The procedure induces apoptosis of the irradiated lymphocytes, but the exact mechanism by which ECP exerts its therapeutic effect in these different conditions is uncertain. The treatment has very few adverse effects and in particular is not associated with an increased incidence of opportunistic infections. The evidence for the efficacy of ECP has been appraised by a combined British Photodermatology Group and U.K. Skin Lymphoma Group workshop on the basis of evidence published up to the end of 2001 and on the consensus of best practice. There is fair evidence for the use of ECP in erythrodermic CTCL and steroid-refractory GVHD, but randomized controlled studies are needed. There is good evidence supporting the use of ECP in preventing cardiac rejection following transplantation. Randomized controlled trials have also shown a therapeutic benefit in type 1 diabetes mellitus, but the inconvenience associated with the procedure outweighed the clinical benefit. There is fair evidence not to use ECP for the treatment of systemic sclerosis and multiple sclerosis, and good evidence not to use ECP for other forms of CTCL.

Bicentre experience in the treatment of severe generalised atopic dermatitis with extracorporeal photochemotherapy

Pilot studies have shown an improvement of atopic dermatitis in approximately 65% of patients during extracorporeal photopheresis (ExP) therapy. The purpose of the present clinical trial was to investigate the response to ExP by controlling clinical and laboratory parameters during short term ExP therapy in patients with severe generalised atopic dermatitis. Thirty-five patients with severe, therapy-resistant atopic dermatitis were treated with ExP in an open clinical trial at two week intervals over a period of 6 to 10 cycles. Disease activity was measured before each cycle by SCORAD index together with a standardized protocol for blood samples. ExP led to a significant decrease (p < 0.05) in SCORAD from 74.4 +/- 15.5 before to 36.8 +/- 16.8 after ExP therapy (mean 10 cycles). Approximately 70% (24/33 patients = responder) of patients had a favourable response to ExP requiring at least 6 cycles. The decrease in SCORAD was accompanied by a significant decrease of eosinophil cationic protein (27%), sE-selectin (37%) and sIL-2R (53%) levels in serum (p < 0.05). No significant correlation between a decrease in these levels and values of blood eosinophils or lymphocytes was found (p > 0.05). In comparison to responders, most non-responders were characterised by very high levels of total IgE before and during therapy (p < 0.05). The present clinical trial confirms that short term ExP is an effective treatment for certain patients with severe atopic dermatitis based on anti-inflammatory mechanisms. Total IgE could be a predictor of outcome in ExP treatment.

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.

The effect of extracorporeal photopheresis on intracellular cytokine expression in chronic cutaneous graft-versus-host disease

BACKGROUND

Cytokines derived from T helper (Th)1 lymphocytes are thought to be involved in the pathogenesis of graft-versus-host disease (GVHD) and extracorporeal photopheresis (ECP) has been reported to affect Th1/Th2 lymphocyte ratios. It may also influence the balance of cytotoxic Tcells (Tc1/Tc2).

OBJECTIVES

This study was formulated to assess the effect of ECP on the cytokine profiles of peripheral blood (PB) lymphocytes from patients with chronic GVHD.

PATIENTS AND METHODS

Nine patients were studied. Peripheral blood was sampled at baseline and between 3 and 4 months of therapy when clinical effects are demonstrable. Intracellular cytokine production was assessed in vitro by stimulating PB lymphocytes with phorbol-12-myristate 13-acetate (PMA), inhibiting cytokine release and staining with fluorescein-labelled monoclonal antibodies to interleukin (IL)-2, interferon gamma (IFN-gamma) and IL-4. Flow cytometry analysis gave the absolute number and the percentage of cells expressing a particular cytokine within each lymphocyte subset.

RESULTS

Absolute counts of CD3, CD4, CD8, CD19 and CD16+ cells per microlitre were recorded before and after ECP. There was a small but non-significant reduction in all subsets after 3 months of ECP. The percentage of cells expressing IL-2 and IFN-gamma rose following ECP in both the CD4 and CD8 subsets. However, only the percentage of CD4 cells expressing IFN-gamma reached statistical significance (P = 0.02; 95% confidence interval, CI 0.6-15.6). There were no significant changes in the percentage of CD4 cells expressing IL-4.

CONCLUSIONS

Our findings appear to be inconsistent with current theories regarding the pathogenesis of GVHD as increased production of Th1 or Tc1 cytokines might be expected to exacerbate GVHD. However, chronic GVHD is characterized by a relative deficiency of IL-2 and IFN-gamma producing cells compared with other patients post-bone marrow transplantation (BMT). This indicates that Th1 and Tc1 cytokines are depleted in chronic GVHD. Thus, by reducing disease activity, ECP could allow cytokine production by these cells to recover. This indicates that the therapeutic effect of ECP is mediated by a different mechanism, and that the changes observed in this study are epiphenomena.

The treatment of cutaneous T-cell lymphoma with photopheresis

Photopheresis or extracorporeal photochemotherapy (ECP) is an immunomodulating procedure that has been available for the treatment of cutaneous T-cell lymphoma (CTCL) since 1987. A concentrated white blood cell (WBC) sample spiked with 8-methoxypsoralen (methoxsalen) is exposed to an ultraviolet A light source, then all blood components are returned to the patient. Treatment of mycosis fungoides (MF) and Sézary syndrome (SS) with ECP has been reported in over 400 patients. The combined overall response rate for all stages of CTCL is 55.7% (244 out of 438) with 17.6% (77 out of 438) achieving a complete response. Efficacy in treating certain clinical stages (IB, IIA, III and IVA) and skin stages (T2 and T4) of MF and SS is favorable, although randomized trials comparing ECP to other standard therapies are needed. The use of ECP to treat early stage patients remains controversial. Efforts to establish the effectiveness of combining ECP with other newer immunoadjuvant therapies and modifications of the procedure to enhance immunomodulation are exciting prospects for patients with CTCL.

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.

The relevance of peripheral blood T-helper 1 and 2 cytokine pattern in the evaluation of patients with mycosis fungoides and Sézary syndrome

BACKGROUND

There is evidence that a T-helper (Th) 2 cytokine pattern dominates in the peripheral blood as well as in tissue of patients with Sézary syndrome (SS), and that the malignant clone is of Th2 phenotype. However, there are conflicting studies on the cytokine pattern in the peripheral blood in different stages of cutaneous T-cell lymphoma (CTCL).

OBJECTIVES

To examine, by means of flow cytometry (FC), the Th1/Th2 cytokine profile [cytoplasmic interferon (IFN)-gamma/interleukin (IL)-4] in peripheral blood T cells from patients with mycosis fungoides (MF) and SS, the most common forms of CTCL, and to correlate their expression with clinical stage, clonality and T-cell immunophenotype changes in order to evaluate their relevance in CTCL progression.

METHODS

We investigated by FC the percentage of CD3+ T cells expressing cytoplasmic IFN-gamma and IL-4 after stimulation in blood specimens of 43 CTCL patients (32 stage I-II and 11 stage III-IV), eight of whom were erythrodermic. Next, we compared cytoplasmic IFN-gamma and IL-4 expression between patients of different stages and controls, and correlated our findings to T-cell receptor (TCR)-gamma gene rearrangement, used as a marker of clonality, and changes in T-cell immunophenotype (CD4+, CD8+, CD4+/CD7-, CD4+/CD25+) and natural killer cells. Polymerase chain reaction amplification of the TCR-gamma gene was performed in 41 blood and 26 skin specimens. We also examined the cytokine expression pattern in patients with erythrodermic MF and SS.

RESULTS

A significantly higher frequency of CD3+/IL-4+ T cells was found in late (III-IV) compared with early (I-II) CTCL patients (P = 0.002) or controls (P < 0.001). There were significant positive correlations between the percentages of CD3+/IL-4+ and the percentages of CD3+/CD4+ T cells (r = 0.385, P = 0.05), CD4+/CD7- T cells (r = 0.335, P < 0.05) and CD4+/CD25+ T cells (r = 0.433, P = 0.01); there was a negative correlation between the percentages of CD3+/IL-4+ and CD3+/CD8+ T cells (r = -0.463, P = 0.005) and a positive correlation between the percentages of CD3+/IFN-gamma+ and CD3+/CD8+ T cells (r = 0.368, P = 0.02). Increased percentages of CD3+/IL-4+, CD3+/CD4+ and CD4+/CD7- T lymphocytes were associated with the presence of clonality (P = 0.025, P < 0.001 and P = 0.0031, respectively). All independent variables showed a statistically significant difference between SS and erythrodermic MF patients, or controls, apart from cytoplasmic IL-4, which was high both in erythrodermic MF and SS patients compared with controls (P = 0.003 and P = 0.008, respectively). In multiple regression logistic analysis, the probability of belonging to advanced CTCL stages was associated only with increased cytoplasmic IL-4 (P = 0.007, odds ratio 1.13, 95% confidence interval 1.033-1.229).

CONCLUSIONS

Increased T-cell cytoplasmic IL-4 is more frequent in late CTCL stages, correlates with T-cell immunophenotype changes found in advanced disease and is associated with clonality. Increased cytoplasmic IL-4 is frequent both in erythrodermic MF and SS patients, in contrast to other variables found increased only in SS, suggesting that IL-4 may be an early indicator of disease progression. Moreover, our results show that increased cytoplasmic IL-4 is the sole predictor of advanced CTCL disease and confirm the relevance of FC determination of IL-4 in the routine evaluation of CTCL cases.

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.

Augmentation of monocyte interleukin-8 production by psoralen/UVA-treated CD4+ T cells

Treatment of cells with psoralen and ultraviolet A light (UVA) modulates their cytokine production. As extracorporeal photochemotherapy has been reported to induce cytokine production by monocytes, we quantified interleukin-8 (IL-8), a representative chemokine produced by monocytes, in culture supernatants from human peripheral blood mononuclear cells (PBMC) treated with 8-methoxypsoralen (8-MOP) and UVA. Lipopolysaccharide stimulated IL-8 production in 8-MOP-phototreated PBMC more efficiently than those untreated or treated with 8-MOP or UVA. More interestingly, when cultured with T-cell-stimulating anti-CD3 and anti-CD28 antibodies, 8-MOP/UVA-treated PBMC produced enhanced amounts of IL-8 with an increased level of IL-8 mRNA expression. Depletion of CD4 but not CD8 T cells from PBMC abrogated this augmented IL-8 elaboration, and CD4 T cells per se secreted no substantial amount of IL-8 even upon CD3/CD28 stimulation. Thus, 8-MOP/UVA-treated CD4 T cells stimulated monocytes to secrete IL-8. The IL-8 overproduction was induced by direct contact of monocytes with 8-MOP/UVA-treated CD4 T cells but not by cytokines from the treated CD4 T cells. These findings imply that in extracorporeal photochemotherapy, monocytes effectively produce IL-8 by cell-to-cell contact with 8-MOP/UVA-treated malignant CD4 T cells. The augmentation of monocyte cytokine/chemokine production by 8-MOP/UVA may be one of the mechanisms underlying the therapeutic efficacy of extracorporeal photochemotherapy.

p53 mutation in nonmelanoma skin cancers occurring in psoralen ultraviolet a-treated patients: evidence for heterogeneity and field cancerization

A combination of psoralens and ultraviolet A radiation is widely used to treat psoriasis. Long-term, high-dose exposure to psoralen + ultraviolet A is associated with an increased risk of nonmelanoma skin cancer, particularly squamous cell carcinoma. In this study, we used p53 mutations as a molecular marker to determine the separate contributions of psoralen + ultraviolet A and other ultraviolet exposures, such as ultraviolet B for skin cancer development in psoralen + ultraviolet A-treated psoriasis patients. The results indicated that of 69 tumors analyzed, 37 (54%) tumors had one or more p53 mutations. Of 37 tumors with mutations, 17 (46%) tumors had only ultraviolet-type mutations, two (5%) tumors had only psoralen + ultraviolet A-type mutations, and 18 (49%) tumors had both types of mutations. Interestingly, psoralen + ultraviolet A-type p53 mutations were more frequent than ultraviolet type in tumors arising in patients with high-dose exposure to psoralen + ultraviolet A. Field cancerization and tumor heterogeneity appeared to occur frequently in the same patient and even in the same tumor. This study's data suggest that psoralen + ultraviolet A-induced p53 mutations may play an important part in the development of nonmelanoma skin cancer in psoralen + ultraviolet A-treated patients, but these mutations are likely to act in concert with the effects of other carcinogenic exposures, particularly ultraviolet B, in the development of skin cancer.

Photoactivational cytokine-modulatory action of 8-methoxypsoralen plus ultraviolet A in lymphocytes, monocytes, and cutaneous T cell lymphoma cells

Treatment with 8-methoxypsoralen (8-MOP) and ultraviolet A light (UVA) has been reported to modulate cytokine production in various cells. Our study was conducted to see the effects of 8-MOP/UVA on the expression/production of cytokines in peripheral blood lymphocytes and monocytes in relation to the therapeutic mechanisms of extracorporeal photochemotherapy. 8-MOP/UVA augmented the expression of mRNAs for interferon-gamma (IFN-gamma) and interleukin (IL)-2 and reduced those for IL-4 and IL-10 in peripheral blood mononuclear cells (PBMCs) from normal subjects and Sézary syndrome patients. This enhancement of Th1 cytokines was caused by increment of cytokine production by Th1 cells but not by conversion of Th2 cells to produce Th1 cytokines. The number of IFN-gamma-secreting lymphocytes was markedly increased in 8-MOP/UVA-treated PBMCs 20 h after treatment, and its amount was elevated in culture supernatants. However, this enhanced production of IFN-gamma was found only until three days after 8-MOP phototreatment, and its level was rapidly declined by five days after treatment. In addition to this Th1-polarized action, 8-MOP/UVA-treated PBMCs produced enhanced amounts of IL-8 upon stimulation with anti-CD3/CD28 antibodies. Phototreated CD4+ but not CD8+ cells provided excellent T cell help for monocytes to produce IL-8 via a direct cell-to-cell contact mechanism. These findings suggest that 8-MOP/UVA has a transient but biologically active Th1-skewing action in T cells, and the phototreated T cells simultaneously stimulate monocytes to produce IL-8. It is suggested that 8-MOP/UVA exerts a beneficial therapeutic effect on malignant Th2 neoplasms as a Th1-skewing cytokine modifier and that 8-MOP-phototreated CD4+ T cells allow monocytes to become effective tumor antigen-presenting cells for tumor-specific cytotoxic T cells.

What are the most promising strategies for the therapeutic immunomodulation of allergic diseases?

Specific immunotherapy and other immunomodulatory strategies have long been a stronghold in the management of allergic diseases. In particular, "immunodeviation-therapy" or "vaccination for allergies", i.e. the redirection of Th2-type immune responses towards a Th1-response pattern, has become an ever more popular concept. The present feature of CONTROVERSIES complements our previous discussion of atopy (Röcken et al., Exp Dermatol 7: 97--104, 1998), and is dedicated to a critical analysis of the general problems and limitations one faces with the main immunomodulatory strategies traditionally considered in this context. We also explore alternative approaches that appear promising in order to achieve both a more effective and/or a more specific immunotherapy of allergic diseases. Given that the mast cell remains a key protagonist in the pathogenesis of allergic diseases finally, this feature examines how innovative, more selectively mast cell-targeted strategies may be developed for the management of allergic diseases.

Treatment of peripheral blood mononuclear cells with 8-methoxypsoralen plus ultraviolet A radiation induces a shift in cytokine expression from a Th1 to a Th2 response

Treatment with 8-methoxypsoralen plus ultraviolet A radiation and extracorporeal photochemotherapy (photopheresis) are widely used for the treatment of psoriasis and other inflammatory skin diseases, graft-versus-host disease, and mycosis fungoides. As the ratio of Th1 and Th2 cells appears to be critical for pathogenesis and progression of these disorders the effect of psoralen plus ultraviolet A on Th1 and Th2 cytokine production by CD4+ lymphocytes was investigated. Human peripheral blood lymphocytes were incubated in the presence of anti-CD3, rh-IL2, and rh-IL4 for 48 h. After subsequent stimulation with rh-IL2 and rh-IL4 for 72 h cells were treated with 8-methoxypsoralen (100, 500, 1000 ng per ml) plus ultraviolet A (2 J per cm2) and incubated for a further period of 5 h in the presence of ionomycine, phorbol-12-myristate acetate and monensin. Fluorescence-activated cell sorter analysis revealed a significant reduction of interleukin-2- and interferon-gamma-producing CD4+ cells upon psoralen plus ultraviolet A treatment depending on the concentration of 8-methoxypsoralen. In contrast, interleukin-4-producing CD4+ cells were increased, indicating a shift from Th1 to a Th2 cell cytokine profile upon psoralen plus ultraviolet A treatment. These results indicate that 8-methoxypsoralen photochemotherapy of lymphocytes is able to modulate their Th1/Th2 distribution. Inhibition of Th1 cytokine expression by psoralen plus ultraviolet A might help to explain its beneficial effects in the treatment of Th1 dominated skin diseases.