PUVA therapy decreases HLA-DR+ CDIa+ Langerhans cells and epidermal cell antigen-presenting capacity in human skin, but flow cytometrically-sorted residual HLA-DR+ CDIa+ Langerhans cells exhibit normal alloantigen-presenting function

Narrow-band ultraviolet B phototherapy versus broad-band ultraviolet B or psoralen-ultraviolet A photochemotherapy for psoriasis

BACKGROUND

The most commonly used types of phototherapy for treating psoriasis are narrow-band ultraviolet B (NB-UVB); broad-band ultraviolet B (BB-UVB), which includes selective (delivering radiation with a wavelength range of 305 to 325 nm) and conventional BB-UVB (280 to 320 nm); and psoralen ultraviolet A photochemotherapy (oral or bath PUVA). There is substantial controversy regarding their efficacy when compared with each other.

OBJECTIVES

To assess the effects of narrow-band ultraviolet B phototherapy versus broad-band ultraviolet B or psoralen ultraviolet A photochemotherapy for psoriasis.

SEARCH METHODS

We searched the following databases up to August 2013: the Cochrane Skin Group Specialised Register, CENTRAL in The Cochrane Library (2013, Issue 7), MEDLINE (from 1946), and EMBASE (from 1974). We searched the following databases up to November 2012: CNKI (from 1974) and CBM (from 1978). We also searched trials registers and the OpenGrey database.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) that compared NB-UVB phototherapy with BB-UVB or PUVA for treating psoriasis, which included chronic plaque psoriasis (CPP), guttate psoriasis (GP), and palmoplantar psoriasis (PPP).

DATA COLLECTION AND ANALYSIS

Two review authors independently conducted the study selection, 'Risk of bias' assessment, and data extraction.

MAIN RESULTS

We included 13 RCTs, with a total of 662 participants. We report the results of intention-to-treat analyses (ITT) here. Our primary outcomes of interest were as follows: Participant-rated global improvement, Percentage of participants reaching Psoriasis Area and Severity Index (PASI) 75 (which meant equal to or more than 75% reduction in PASI score), Withdrawal due to side-effects, and Clearance rate.In one RCT of NB-UVB compared with oral PUVA in participants with CPP, the difference in PASI 75 was not statistically significant (risk ratio (RR) 0.91, 95% confidence interval (CI) 0.63 to 1.32; N = 51; low quality). In three other RCTs of CPP, the clearance rates were inconsistent because in one, there was no difference between the groups (RR 1.01, 95% CI 0.91 to 1.12; N = 54), and in the other two, the clearance rates were statistically significantly in favour of oral PUVA: RR 0.66, 95% CI 0.47 to 0.93; N = 93 and RR 0.75, 95% CI 0.59 to 0.96; N = 100, respectively. Pooled data from these three studies indicated that withdrawals due to adverse events were not significantly different between either group (RR 0.71, 95% CI 0.20 to 2.54; N = 247; low quality).The evidence from the comparison of NB-UVB with bath PUVA in terms of clearance rate for CPP was also inconsistent: Pooled data from two left-right body comparison RCTs found no significant difference between the NB-UVB and bath PUVA groups (RR 1.79, 95% CI 0.46 to 6.91; N = 92; low quality), while a parallel RCT favoured bath PUVA (RR 0.18, 95% CI 0.05 to 0.71; N = 36; low quality).In participants with PPP, one RCT found there were no significant differences between NB-UVB treated sides and topical PUVA treated sides in terms of clearance rate (RR 0.09, 95% CI 0.01 to 1.56; N = 50; low quality).Two RCTs found NB-UVB plus retinoid (re-NB-UVB) and PUVA plus retinoid (re-PUVA) had similar effects for treating people with CPP or GP in terms of clearance rate (RR 0.93, 95% CI 0.79 to 1.10; N = 90; low quality).One RCT in people with CPP found no significant differences between NB-UVB and selective BB-UVB in terms of clearance rate (RR 1.40, 95% CI 0.92 to 2.13; N = 100; low quality) and withdrawals due to adverse events (RR 3.00, 95% CI 0.32 to 27.87; N = 100; low quality).No studies reported our primary outcomes for NB-UVB compared with conventional BB-UVB.

AUTHORS' CONCLUSIONS

Current evidence is very heterogeneous and needs to be interpreted with caution. The clearance rate between oral PUVA and NB-UVB is inconsistent among the included studies. Evidence regarding NB-UVB versus bath PUVA is also inconsistent. Re-NB-UVB and re-PUVA are similarly effective for treating people with CPP or GP. In practice, NB-UVB may be more convenient to use since exogenous photosensitiser is not required before phototherapy.NB-UVB is considered ineffective for PPP in clinical practice, and a small RCT did not detect a statistically significant difference between NB-UVB and topical PUVA for clearing PPP. NB-UVB seemed to be similar to selective BB-UVB for clearing CPP.Larger prospective studies are needed to confirm the long-term safety of NB-UVB.

Graft-versus-host disease: part II. Management of cutaneous graft-versus-host disease

Dermatologists are ideally suited to manage the various cutaneous sequelae of graft-versus-host disease (GVHD) outlined in part I of this review. However, the complexity of the patient with GVHD, including comorbidities, potential drug interactions related to polypharmacy, and the lack of evidence-based treatment guidelines, are significant challenges to optimizing patient care. In this section, we will provide an outline for the role of the dermatologist in a multispecialty approach to caring for patients with GVHD.

A case of acute cutaneous graft-versus-host disease mimicking psoriasis vulgaris

Graft-versus-host disease (GVHD) is a frequent complication occurring after allogenic hematopoietic stem cell transplantation and is divided into acute and chronic type. Cutaneous involvement is the most frequent manifestation of acute GVHD, with maculopapular exanthema and perifollicular papular lesions. We describe the first case to develop acute cutaneous GVHD mimicking psoriasis vulgaris shortly after allogenic peripheral blood stem cell transplantation. The patient's rash resembled psoriasis vulgaris and showed histologic features of both psoriasis and acute GVHD. Despite various immunosuppressant therapies, the skin lesion was drug-resistant. Therefore, we administered psoralen-UVA (PUVA) therapy and achieved the desired therapeutic effect. As far as we know, this is the first case of psoriasiform skin eruption as a manifestation of acute GVHD.

Immunosuppressive effects of photodynamic therapy by topical aminolevulinic acid

Photodynamic therapy (PDT) has been used for inflammatory skin disorders as well as superficial skin cancers such as solar keratosis and Bowen's disease. Whether PDT with topical application of aminolevulinic acid (ALA) and exposure to visible light has a similar immunosuppressive action to ultraviolet phototherapy was investigated using a murine contact hypersensitivity (CHS) model. The number of epidermal Langerhans cells (LC) was decreased with their morphological changes 1 day after PDT with the minimal level at 5 days and gradual recovery thereafter. Conversely, the number of CD11c(+) I-A(+) cells was significantly increased in the draining lymph nodes after PDT. This suggests that LC moved from PDT-treated skin, resulting in the decrement of epidermal LC and migration to lymph nodes. CHS response to DNFB applied on the PDT-treated skin with 20% ALA and 40 J/cm(2) visible light was significantly suppressed (local immunosuppression). When mice were treated with 80 J/cm(2) of PDT, CHS response to the antigen applied on untreated distant skin was also significantly suppressed (systemic immunosuppression). The locally or systemically immunosuppressed mice by PDT were attempted to sensitize again with DNFB on non-treated skin, but elicitation responses were significantly suppressed. However, these mice were able to be sensitized with another hapten, oxasolone. Thus, a hapten-specific immunological unresponsiveness (tolerance) was induced in mice by topical ALA-PDT. These findings suggest that PDT has a potential immunological contribution to clinical efficacy for inflammatory diseases identical to ultraviolet phototherapies.

A quantitative study of epidermal Langerhans cells in cutaneous leishmaniasis caused by Leishmania tropica

OBJECTIVE

The purpose of this study was to characterize the number and distribution of epidermal Langerhans cells in different clinical forms of dry-type cutaneous leishmaniasis (CL).

METHODS

Sixteen cases of dry-type cutaneous leishmaniasis caused by Leishmania tropica were studied. These cases were classified clinically as five cases of acute leishmaniasis with indurated papules, nodules and plaques with central crust formation and duration < 2 years, six cases of lupoid leishmaniasis with characteristic papules around previous scars of cutaneous leishmaniasis with duration > 2 years, and five cases of chronic nonlupoid type with nonhealing lesions of duration > 2 years. Paraffin-embedded blocks were stained with hematoxylin and eosin (H&E) and stained immunohistochemically for CD1a.

RESULTS

The number of Langerhans cells per millimeter length of epidermis was increased in acute cases compared to chronic and lupoid cases.

CONCLUSIONS

Lesions of acute leishmaniasis contain the greatest amounts of antigen for presentation, so Langerhans cells increase in number and in trafficking to present antigens derived from Leishman bodies to the cellular immune system. In chronic leishmaniasis, the Langerhans cell population is reduced, perhaps because of exhaustion of the source of Langerhans cells, or because of reduced response to modified antigen.

Oral PUVA and topical steroids for treatment of oral manifestations of chronic graft-vs.-host disease

BACKGROUND

Oral manifestations of chronic graft-vs.-host disease (cGVHD) can significantly affect the quality of life and severity often does not correlate with systemic manifestations. We evaluated the use of topical corticosteroids and the intraoral application of psoralen-UVA (PUVA) for treatment of oral manifestations of cGVHD.

METHODS

Overall, 18 patients with oral manifestations of cGVHD were treated with either intraoral PUVA (n=7) or with topical corticosteroids (n=16). Four patients received intraoral PUVA after failure of topical steroids and one patient was treated with topical corticosteroids after failing treatment with intraoral PUVA. A glass fiber extension of an UVA source was used for manual intraoral application. Treatment with topical corticosteroids consisted of 0.1 mg/ml dexamethasone mouth wash four times a day in combination with antifungal prophylaxis.

RESULTS

Four patients showed complete local response (CR) due to intraoral PUVA, two improved and one did not respond. Topical corticosteroids resulted in nine patients in CR, two improved and five did not respond.

CONCLUSION

Intraoral PUVA as well as topical corticosteroids are effective in treatment of oral manifestations of oral GVHD with few side-effects and improve quality of life in patients with cGVHD.

Psoralen plus ultraviolet-A-bath photochemotherapy as an adjunct treatment modality in cutaneous chronic graft versus host disease

BACKGROUND

Cutaneous chronic graft versus host disease (GVHD) is a severe complication following allogeneic stem cell (PBSCT) and bone marrow transplantation (BMT). Immunosuppressive therapy consists of prednisone, cyclosporine-A, azathioprine or mycophenolate mofetil (MMF). Treatment of patients refractory to immunosuppression represents a major problem.

METHODS

We report six patients suffering from severe chronic GVHD of the skin who did not respond to immunosuppressive therapy or relapsed after reduction of glucocorticosteroids. Patients were treated with psoralen plus ultraviolet (PUVA)-bath photochemotherapy three times weekly following a standardized treatment protocol under continued treatment with prednisone and/or MMF. One patient was additionally pretreated with ultraviolet-A1 (UV-Al).

RESULTS

After a median of 14, 5 treatment sessions, skin lesions improved. Out of six patients, three showed a complete remission. In all patients, systemic immunosuppressive therapy could be reduced. In sclerodermic lesions, skin thickness returned to the levels of normal skin after 25 treatments confirmed by 20 MHz ultrasound evaluation. In a follow-up ranging from 2 to 21 months (median 10, 3 months), skin conditions remained stable.

CONCLUSION

Psoralen plus ultraviolet-A-bath represents an effective adjunct treatment option for extensive chronic and sclerodermic cutaneous GVHD offered by dermatologists. This is of high interest in patients suffering from cutaneous GVHD resistant to conventional immunosuppressive therapy and should be included to the menu of topical treatment options for chronic cutaneous GVHD.

Psoriasis. Immunopathology and immunomodulation

Biologics in development for the treatment of moderate to severe plaque-type psoriasis are discussed in this article. Immunomodulators used as therapeutic, pathogenic probes will continue to identify targets that play primary roles in the pathogenesis of psoriasis.

Ultraviolet B irradiation: a new therapeutic concept for the management of oral manifestations of graft-versus-host disease

Ultraviolet irradiation inhibits the proliferative responses of lymphoid cells to mitogens and alloantigens by inactivation of T lymphocytes and antigen-presenting cells. Its immunosuppressive capacity led to the introduction of UV irradiation into clinical practice for the treatment of dermatologic manifestations of chronic graft-versus-host disease. The cumulative experience with psoralen-UV-A rays in the treatment of cutaneous and oral graft-versus-host disease was the incentive for the application of oral UV-B rays in 2 patients with oral graft-versus-host disease signs and symptoms after allogeneic marrow transplantation. Intraoral UV-B irradiation (0.02 mJ/cm(2)) was administered 2 or 3 times per week on an ambulatory basis; the dose was increased by 0. 02 mJ/cm(2) every fourth session. Both patients responded early and satisfactorily, displaying only minimal side effects at a relatively low cumulative dose. Intraoral UV-B proved a valuable modality in the treatment of resistant chronic oral graft-versus-host disease.

In situ action spectra suggest that DNA damage is involved in ultraviolet radiation-induced immunosuppression in humans

The mixed epidermal cell lymphocyte reaction (MECLR) is a commonly used method to study the immunomodulatory effects of UV radiation. The in vitro action spectrum for the MECLR showed that the UV-induced suppression of the MECLR responses is associated with UV-induced DNA damage. To investigate whether in vivo DNA damage also leads to the abrogation of the MECLR, in situ action spectra were made for the MECLR and the induction of thymine dimers (T < > T). Human skin, obtained from plastic surgery, was exposed to monochromatic light of 254, 297, 302 and 312 nm. After irradiation, epidermal cells were isolated and used as stimulator cells in the MECLR or processed for flow cytometric detection of T < > T. On the basis of dose-response curves for each wavelength, the action spectra for suppression of the MECLR and the induction of T < > T were calculated. These spectra showed close similarities, suggesting that, also in situ, UV-induced DNA damage is involved in the UV-induced suppression of the MECLR. Both action spectra showed a small decline from 254 nm to 302 nm, followed by a steep decline to 312 nm. These data show that, in situ, UVC can efficiently induce DNA damage and modulate cutaneous immune responses.

Differential suppression of the human mixed epidermal cell lymphocyte reaction (MECLR) and mixed lymphocyte reaction (MLR) by cis-urocanic acid

Cis-urocanic acid (UCA), formed in the stratum corneum by UV irradiation of trans-UCA has been proposed as a mediator of UV-induced immunosuppression in the skin. In this study, we examined the in vitro effect of cis-UCA (6-100 micrograms/mL) on the human mixed lymphocyte reaction (MLR) and the mixed epidermal cell lymphocyte reaction (MECLR). Addition of cis-UCA (purified or in a mixture with trans-UCA) did not affect the MLR but was able to induce a 20% suppression of the MECLR responses. Because this effect of cis-UCA on the MECLR was not as strong as could be expected from previous in vivo results, we designed a set of experiments in order to enhance the in vitro immunosuppressive capacity of cis-UCA. Firstly, we preincubated epidermal cells with UCA (50 micrograms/mL). for 3 or 6 days before culture in the MECLR because in vivo repeated UV exposure can lead to a photostationary state, where cis-UCA may be present for several weeks. This pretreatment with cis-UCA resulted in a maximal decrease of the MECLR response of 27%, whereas trans-UCA had no effect. Secondly, we investigated whether UVB irradiation of epidermal cells could make cells more sensitive to cis-UCA. However, addition of trans- or cis-UCA did not potentiate the reduced alloactivating capacity of UVB-irradiated cells. Finally, we examined the possibility of a synergistic effect of cis-UCA with histamine. Addition of histamine suppressed the MLR and MECLR responses, but neither cis- nor trans-UCA were able to modulate this decrease. We conclude that cis-UCA can partly downregulate the human MECLR but not the MLR. The mechanism involved in this differential downregulation is not known. In this respect it is striking that cis-UCA dose not potentiate the UVB- or histamine-induced suppression of the MECLR.

PUVA treatment selectively induces a cell cycle block and subsequent apoptosis in human T-lymphocytes

Psoralen plus UVA (320-400 nm radiation; PUVA) is a highly effective therapy for cutaneous diseases caused by skin infiltration with normal or neoplastic T-lymphocytes. In comparing the effects of pharmacologically relevant, low-dose PUVA treatment on growth of human keratinocytes, peripheral blood leukocytes (PBMC), and T-lymphocyte cell lines, we determined that PBMC or T-lymphocytes were > 50-fold more sensitive to cytotoxic effects of PUVA, while antiproliferative effects were produced by similar PUVA levels in all cell types. Low doses of PUVA (10 ng/mL 8-methoxypsoralen and 1-2 J/cm2) were highly cytotoxic for phytohemagglutinin-activated normal lymphocytes or transformed T-lymphocytes as assessed by two viability assays and by flow cytofluorometry. Altered lymphocyte morphology, nuclear fragmentation, TUNEL+ nuclei or nuclear fragments, and the appearance of a sub-G1 DNA peak indicated that cell death occurred by apoptosis, beginning about 1 day after PUVA treatment and continuing for several days thereafter. From assessment of cell cycle progression in mimosine-synchronized cells, PUVA treatment markedly slowed cell cycle progression, eventually producing cell cycle arrest and apoptotic entry. We propose that the probable basis for disease remissions (psoriasis, cutaneous T-cell lymphoma) produced by PUVA treatment is through selective cytotoxic effects on clonal T-lymphocyte populations that are concentrated in diseased skin.

The action spectra for UV-induced suppression of MLR and MECLR show that immunosuppression is mediated by DNA damage

Ultraviolet-B (UVB, 280-320 nm) radiation can promote the induction of skin cancer by two mechanisms: damage of epidermal DNA and suppression of the immune system, allowing the developing tumor to escape immune surveillance. The mixed lymphocyte reaction (MLR) and the mixed epidermal cell lymphocyte reaction (MECLR) are commonly used methods to study the immunosuppressive effects of UVB radiation. To obtain a better understanding of the mechanism by which UVB radiation decreases the alloactivating capacity of in vitro-irradiated cells, action spectra for the MLR and MECLR were determined. Suspensions of peripheral blood mononuclear cells or epidermal cells were irradiated with monochromatic light of 254, 297, 302 or 312 nm and used as stimulator cells in the MLR or MECLR. Using dose-response curves for each wavelength, the action spectra were calculated. Both MLR and MECLR action spectra had a maximum at 254 nm and a relative sensitivity at 312 nm that was a thousand times lower than at 254 nm. Strikingly, the action spectra corresponded very closely to the action spectra that were found by Matsunaga et al. (Photochem. Photobiol. 54, 403-410, 1991) for the induction of thymine dimers and (6-4)photoproducts in irradiated calf thymus DNA solutions, strongly suggesting that the UV-induced abrogation of the MLR and MECLR responses is mediated by UV-induced DNA damage. Furthermore, the action spectra for the MLR and MECLR were similar, suggesting that they share a common mechanism for UV-induced suppression.

UVB-induced suppression of the mixed epidermal cell lymphocyte reaction is critically dependent on irradiance

The mixed epidermal cell lymphocyte reaction (MECLR) is a commonly used method to study the effects of ultraviolet B (UVB) radiation on the skin immune system. In UVB experiments dosimetry is very important. The influence of irradiance on the MECLR was studied in vitro using Philips FS40 lamps with variable UV intensities. Irradiation of isolated epidermal cells with high irradiance impaired the alloactivating capacity more than irradiation with low irradiance. In vivo, the influence of long-term UVB exposure on the MECLR was studied by treating normal healthy volunteers with suberythemagenic doses of UVB thrice weekly during 4 weeks. The first set of experiments, using low irradiance Sylvania UV-21 F75/85 W lamps, resulted in a decrease of MECLR responses of 83.1%. In the second set of experiments performed a year later, employing an identical protocol except for the use of high irradiance Waldmann UV-21 F85/100 W lamps, an increase of MECLR responses of 99.7% was observed. Volunteers of both sets of experiments received equal doses of UVB. In conclusion, this study shows that in vitro UVB-induced suppression of the MECLR is critically dependent on irradiance and therefore might explain contradictory results described in the literature. The in vivo data suggest that, comparable to the in vitro experiments, irradiance may influence the effects of UVB irradiation in vivo. Further experiments should prove whether this is indeed the case.

PUVA bath therapy strongly suppresses immunological and epidermal activation in psoriasis: a possible cellular basis for remittive therapy

Psoriasis is characterized by alterations in both the epidermis and dermis of the skin. Epidermal keratinocytes display marked proliferative activation and differentiate along an "alternate" or "regenerative" pathway, while the dermis becomes infiltrated with leukocytes, particularly interleukin 2 (IL-2) receptor-bearing "activated" T cells. Psoralens, administered by the oral route, have therapeutic effects in psoriasis when photochemically activated by ultraviolet A light (PUVA therapy). Recently psoralen bath therapy has been introduced to more effectively deliver this agent to the diseased skin. We have correlated the efficacy of PUVA bath therapy with its effects on specific molecular and cellular parameters of disease, in 10 consecutive patients with recalcitrant psoriasis. Rapid clearing of lesions occurred in 8 out of 10 patients. Biopsies were taken from lesional and nonlesional skin before and after a single round of therapy, and observation was continued in our Clinical Research Center at The Rockefeller University. Enumeration of cycling keratinocytes with the Ki-67 monoclonal antibody showed that PUVA reduced cell proliferation by 73%. The pathological increase in insulin-like growth factor 1 (IGF-1) receptors was reversed, whereas epidermal growth factor (EGF) receptors, which are also increased in psoriasis, remained unchanged. Keratinocyte proteins that are expressed in abnormal sites of the epidermis during psoriasis, i.e., keratin 16, filaggrin, and involucrin, were, after PUVA treatment, localized to their normal sites. Epidermal and dermal T-lymphocytes (CD3+), as well as CD4+, CD8+, and IL-2 receptor+ subsets, were strongly suppressed by PUVA, with virtual elimination of IL-2 receptor+ T cells in some patients. Consistent with diminished lymphocyte activation, HLA-DR expression by epidermal keratinocytes was markedly reduced in treated skin. In comparison to cyclosporine treatment of psoriasis, PUVA therapy leads to more complete reversal of pathological epidermal and lymphocytic activation, changes which we propose to be the cellular basis for a more sustained remission of disease after PUVA treatment.

The effect of UV therapy on immune function in patients with psoriasis

Ultraviolet radiation (UVR) is known to suppress some cell-mediated immune responses to antigens encountered during or soon after exposure. Phototherapy is widely used in psoriasis, and this study was undertaken to monitor changes in a range of immunological parameters during standard courses of treatment, with the aim of ascertaining whether such modulations contribute to the effectiveness of therapy. The responses of 17 patients with psoriasis undergoing UVB therapy, and four receiving PUVA therapy, were compared with 15 patients receiving coal tar treatment and four normal subjects undergoing UVB irradiation. In each case, samples were taken before starting therapy, after 4 weeks of therapy, and 4 weeks after completion of treatment. Serum immunoglobulin isotypes and complement components were within normal ranges in most of the psoriasis patients, and remained unchanged throughout therapy. Similarly, percentages of subsets of peripheral blood mononuclear cells (PBMC) were normal, and were unaltered by treatment. Patients who were already infected with herpes simplex virus (HSV), as demonstrated by a positive lymphoproliferation test in vitro, were monitored for asymptomatic HSV shedding and HSV recrudescences during therapy. There was little evidence that phototherapy caused reactivation of the virus. No significant alteration in lymphoproliferative response to HSV and to the mitogen concanavalin A was observed during therapy. Epidermal cells and blood adherent cells were used to present HSV to PBMC, depleted of adherent cells and enriched for T cells, in a lymphoproliferative assay. The functional antigen-presenting ability of adherent cells remained unchanged throughout therapy, whereas that of epidermal cells was suppressed during UVB irradiation and recovered, in most instances, after UVB therapy had been completed. The epidermis of patients with psoriasis contained about three times the quantity of urocanic acid (UCA) of normal subjects, whereas the UCA concentration in suction blister fluid did not differ between the two groups. During UVB irradiation, the percentage of cis-UCA rose in both the epidermis and suction blister fluid of all subjects, and it remained elevated in the blister fluid after therapy had finished. Tumour necrosis factor-alpha was measured in suction blister fluid, and its concentration did not alter consistently as a result of therapy. Whether any of the immunological parameters measured, and the changes noted, contribute to the effectiveness of phototherapy in the treatment of psoriasis remains uncertain.

Major histocompatibility class II antigen expression on the surface of epidermal cells from normal and ultraviolet B irradiated subjects

The influence of ultraviolet B irradiation in therapeutic doses on MHC II-positive epidermal cell numbers and their surface MHC II antigen expression was studied quantitatively using light microscopic immunoperoxidase and immunogold electron microscopic techniques. In multiple ultrathin sections through many MHC II-positive epidermal cells from five healthy subjects, prior to ultraviolet exposure, Langerhans cells and indeterminate cells were found to express similar densities of surface MHC II antigens, which were uniformly distributed over the cell surface. The variation in surface MHC II antigen expression on 97 dendritic epidermal cells from one subject was normally distributed. Following a 6-week course of ultraviolet B irradiation, in the same doses as those normally used for the treatment of psoriasis, MHC II-positive epidermal cell numbers were significantly reduced (mean decrease to 51% of the pre-UVB sample; p < 0.001 analysis of variance), but their surface MHC class II antigen density was significantly increased (p < 0.05 analysis of variance). No MHC II-negative Langerhans cells were detected in either the pre- or post-UVB samples.

Effects of cyelosporin A on resident and passenger immune cells of normal human skin and UV-induced erythema reactions

Cyclosporin A (CyA) has proved effective in various dermatological diseases, but its mechanisms of action within the skin are still ill-defined. In order to characterize more clearly the cellular targets of CyA we examined its effects on skin immune cells in normal and UVB- and PUVA-irradiated skin by means of a three-step immunoperoxidase reaction and immunofluorescence double-labelling technique. The CyA-induced depletion of epidermal Langerhans cells equals that seen with UVB or PUVA alone. CyA alone has no effect on the number and distribution of dermal cells. CyA modulates the UV irradiation-induced changes by: (i) inhibiting the UVB- and PUVA-induced ICAM-1 expression by keratinocytes and (ii) suppressing the PUVA-induced upregulation of CD11a expression by macrophages (72 +/- 12% of Ki-M8+ macrophages express CD11a with PUVA, compared with 20 +/- 5% with CyA + PUVA, P < 0.001). Neither treatment affected ICAM-1 expression by endothelial cells. In addition, CyA increases PUVA minimal phototoxicity dose from 10 +/- 2.6 J/cm2 (PUVA alone) to 15.3 +/- 3.1 J/cm2 (CyA + PUVA), (P < 0.001). In conclusion, the effects of CyA on the skin include a down-modulation of the PUVA-erythema reaction, associated with a direct or indirect modulation of adhesion molecule expression.

Selective activation of circulating CD4+ lymphocytes in severe adult atopic dermatitis

An analysis of peripheral blood lymphocyte subsets and their expression of activation markers was performed using flow cytometry in 12 adult patients with severe atopic dermatitis, and compared with 14 normal individuals. Repeated measurements were made over an 8-week period during which disease activity was also assessed. Increased percentages of activated and unactivated CD4+ lymphocytes, and decreased percentages of CD8+ cells were observed in atopic dermatitis. Increasing disease activity was associated with an increase in the proportion of activated and unactivated CD4+ lymphocytes and a fall in the proportion of CD8+ cells. This study demonstrates that in adults with severe atopic dermatitis, increasing disease activity is associated with selective activation of CD4+ lymphocytes and a relative expansion of the CD4+ cell subset.

Effect of topical sunscreens on the UV-radiation-induced suppression of the alloactivating capacity in human skin in vivo

Exposure of mice or humans to solar or artificial ultraviolet radiation (UV) has been shown to induce a number of changes in the immune system that may influence their susceptibility to skin tumors. The protective effect of sunscreens on these changes is not clear. Thirty-two patients with a variety of dermatoses routinely undergoing treatment with standard UVB (n = 19) or PUVA (n = 13) therapy were studied. One of the two tested sunscreens or its vehicle was applied to the right flexor forearm immediately prior to each total-body UV exposure. Epidermal sheets were obtained by the suction-blister method from the left flexor forearm before treatment and from both flexor forearms after 4 weeks of photo- or photochemotherapy and used as stimulator epidermal cells (EC) in the mixed epidermal cell-lymphocyte reaction (MECLR). After 4 weeks of either UVB or PUVA therapy the MECLR responses on EC from both arms were markedly decreased. Neither the tested sunscreens nor their vehicles prevented the UV-induced suppression of the alloactivating capacity. The failure of sunscreens to protect against the UV-induced suppression of the alloactivating capacity could be explained in two ways. First, the energy not absorbed by the sunscreen could be sufficient to induce suppression of the alloactivating capacity. An alternative explanation could be systemic immune suppression by UV. In order to discriminate between these possibilities only the right forearms of 10 healthy volunteers, treated with a sunscreen or its vehicle, were irradiated with UVB during 4 weeks. In this manner systemic immune suppression by UVB could be excluded. This experiment resulted in a similar suppression of the MECLR responses, as induced by total body UVB irradiation, without any protection by the sunscreen. Apparently, the UV dose not absorbed by the sunscreen was capable to induce suppression of the alloactivating capacity. Our results indicate that people protected from sunburn by sunscreens may be exposed to UV for a long period of time, and thereby subject themselves to its immunosuppressive action.

Cyclosporin A suppresses ICAM-1 expression by papillary endothelium in healing psoriatic plaques

To analyze the mode of action of Cyclosporin A (CsA) in psoriasis, we examined the phenotypic profile of resident and passenger skin cells in seven psoriatic patients before and after 2 weeks of CsA treatment using a large panel of monoclonal antibodies in a three-step immunoperoxidase technique. For comparison, skin biopsies from psoriatic patients receiving psoralen + UVA (PUVA) therapy were examined. Although both treatment protocols were equally effective in inducing resolution of psoriatic lesions, the phenotypic changes induced by CsA differed greatly from those seen after PUVA. In CsA-treated patients there was a dramatic reduction in the ICAM-1 expression by papillary endothelial cells, but density, pattern, and phenotype of infiltrating inflammatory cells remained essentially unchanged. In contrast, PUVA therapy had no visible effect on ICAM-1 expression by papillary endothelial cells, but resulted in a significant reduction of the hemopoietic resident and infiltrating mononuclear cells within the epidermis. These results favor, but do not prove, the assumption that the CsA regimen chosen in this study exerts its anti-psoriatic effect primarily at the level of the keratinocyte, i.e., by inhibiting events leading to keratinocyte proliferation as well as by interfering with the secretion of mediators responsible for ICAM-1 expression by papillary endothelial cells.

Cyclosporin A in combination with photochemotherapy (PUVA) in the treatment of psoriasis

Forty patients with relapsing plaque psoriasis involving more than 20% body surface were treated either with cyclosporin A (CyA) plus PUVA or the retinoid etretinate plus PUVA (RePUVA). They initially received either CyA (2 weeks) or etretinate (1 week) alone and then PUVA was given concomitantly until complete remission. The patients were monitored over a period of 6 months and any relapse recorded. With each combined treatment regimen, CyA plus PUVA and RePUVA, the patients cleared within comparable periods of time (mean treatment period of 5.3 vs. 4.7 weeks after initiation of therapy and 3.3 vs. 3.7 weeks after initiation of PUVA). However, the cumulative UVA dose required for clearance (110.9 J/cm2 vs. 62.1 J/cm2 (P less than 0.05)) and the incidence of severe and early relapses were significantly higher in the CyA cohort. Within 6 months severe relapses had occurred in 58% of CyA plus PUVA but only in 15% of RePUVA-treated patients (P less than 0.001). This suggests that the CyA plus PUVA regimen as performed in this study is less effective than RePUVA.

Side-effects of psoralen photochemotherapy (PUVA)

Although psoralen photochemotherapy (PUVA) is one of the most effective forms of therapy for psoriasis, the risk of potential long-term side-effects is, as yet, not clearly determined. Chronic degenerative and pigmentary skin changes similar to those of chronic solar exposure occur after long-term PUVA treatment; PUVA also causes non-melanoma skin cancers in man, although there is, as yet, no consensus as to what cumulative phototoxic PUVA dose is carcinogenic. Long-term multicentre studies from the U.S.A. indicate a definite risk of squamous cell carcinoma for long-term PUVA-treated patients, whereas European studies reveal no overall increase in skin cancers in similar patients except for those exposed to other carcinogens. Assignment to PUVA should be based on the risk:benefit ratio for the individual patient. Careful patient selection is therefore mandatory and should be limited to those who can be monitored and controlled by informed, competent and conscientious physicians.

Flow cytometric analysis and sorting of HLA-DR+CD1+ Langerhans cells

There is a considerable need for reliable methods for enumeration and enrichment of Langerhans cells (LCs), since they continue to be the subject of intensive investigation in normal and diseased skin. It has been claimed that standard labelling with either anti-HLA-DR or OKT6 antibodies alone may fail to identify potentially important subsets of LCs with the phenotypes HLA-DR+CD1- and HLA-DR-CD1+. We report here on flow cytometric analysis of suction blister-derived normal epidermal cell (EC) suspensions, double stained with phycoerythrin-conjugated anti-HLA-DR and fluoresceinated OKT6. In seven separate experiments, no evidence for the existence of either HLA-DR+CDI- or HLA-DR-CDI+ ECs was obtained. We found that HLA-DR+CDI+LCs, which constituted a mean of 2.5% (+/- 0.3 SEM) of all ECs, could be readily identified on the basis of fluorescence, and that their light scatter characteristics were those of moderately sized cells of low granularity. We further describe our method for flow cytometric enrichment of such HLA-DR+CDi+ LCs for functional studies, based on selection on both fluorescence and light scatter criteria. Enrichment is to greater than 90% purity, and the method is applicable to the small number of ECs (approximately 1 x 10(6] obtained from a suction blister.