Inflammatory involvement into phototoxic reaction in erythropoietic protoporphyria (EPP) patients.

Phototoxic reaction is a known feature of EPP at least in part triggered by the oxidative status, complement system activation, and mast cell response. The aim of this study was to verify some aspects involved in phototoxic reaction during a season. The complement system was evaluated by C3 assay, alternative pathway by factor-B, and classical pathway by C1q; oxidative status was tested with malondialdehyde (MDA) and mast cell by IL-10 assay. The serum samples were collected in winter and summer from 19 EPP patients and 13 controls. The reaction to sun exposure within each group was monitored without any invasive treatment. In summer, C3 and factor B were higher in patients than in controls (p = 0.002 and < 0.0001 respectively), while no change was detected for C1q. The oxidative stress was increased in summer in comparison with the control group (p = 0.04), and IL-10 an assay was normal in both seasons. The correlation between the C3 and factor-B in summer was significant. This study shows that the phototoxic reaction is not limited to the dermis but can also exert a systemic response, which could affect the general health of a patient. The knowledge of the pathophysiology of phototoxic reaction is essential for identifying new disease markers useful for improving clinical studies of known and future drugs.

Study of the sensitising potential of various textile dyes using a biphasic murine local lymph node assay.

Disperse dyes, which are suitable for dyeing synthetic fibres, are responsible for the great majority of allergic contact dermatitis (ACD) cases to textile dyes. The aim of the present study was to investigate the sensitising potential of various disperse dyes using a biphasic protocol of the local lymph node assay (LLNA). Briefly, mice were shaved over a surface of approximately 2 cm(2) on their backs and treated using a "sensitisation-challenge protocol". The shaved surface was treated once daily on days 1-3 with 50 microl of the test solution. Animals remained untreated on days 4-14. On days 15-17, mice were treated with 25 microl of the test solution on the dorsum of both ears. Mice were killed on day 19 with deep CO(2) anaesthesia, the lymph nodes prepared and various end points, such as ear thickness, ear punch weight, lymph node weight, lymph node cell count and the proportion of various lymphocyte subpopulations, were determined by flow cytometry. The results were compared to control group treated with the vehicle alone. Our results showed that almost all of the tested textile dyes caused a significant increase in lymph node cell count and lymph node weight. We also observed an increase in ear thickness and ear punch weight in most of the concentrations tested for various textile dyes. We observed a decrease in CD4+ and CD8+ cells and an increase in CD19+, CD45+ and CD45+/1A+ cells in most of the cases, which is characteristic for allergens. The CD4+/CD69+ cells increased in only few experiments mainly with Disperse Blue 124 and Disperse Blue 106. Based on our results, the disperse dyes could be arranged in four groups on the basis of their sensitising potency in the following decreasing order (in parenthesis: lowest concentration causing a significant increase in lymph node cell number): group 1, strong: Disperse Blue 124 and Disperse Blue 106 (0.003%); group 2, moderate: Disperse Red 1 and Disperse Blue 1 (3%); group 3, weak: Disperse Orange 37 and Disperse Blue 35 (10%); and group 4, very weak: Disperse yellow 3 and Disperse Orange 3 (increase at 30% or no increase at 30%). In conclusion, our study shows that the biphasic LLNA protocol was proficient enough to study the sensitisation potential of tested textile dyes and provides data allowing to discriminate them according to their potency.

Drug-induced photoallergic and phototoxic reactions.

Drug-induced photosensitivity involves reactions to medication triggered by exposure of the skin to ultraviolet light. Medications that trigger reactions can be topical or oral. Following interaction of ultraviolet radiation with a chemical present in sufficient amounts in the skin, one of the several reactions may occur in susceptible patients, most commonly photoallergy or phototoxicity. These reactions can be diagnosed separately based on pathogenesis, clinical characteristics and histopathology. Phototoxic disorders have a higher incidence than photoallergic disorders. The action spectra for most photoallergens and phototoxins lie in the ultraviolet A range. Subtypes of drug-induced photosensitivity include dyschromia, pseudoporphyria, photo onycholysis, and lichenoid and telangiectatic reactions.

[Antigenicity and phototoxicity of water-soluble extract from Salacia reticulata (Celastraceae)].

The antigenicity and phototoxicity of water-soluble extract from Salacia reticulata (SRE) were examined in guinea pigs. In a study of active systemic anaphylaxis reaction, neither the oral administration group (64 or 320 mg/kg, 5 times/week, 3 weeks) nor the subcutaneous administration group (64 mg/kg, 1 time/week, 3 weeks) exhibited any anaphylactic reaction. Moreover, sensitization with serum obtained from these animals did not induce passive cutaneous anaphylaxis reaction in normal animals. In a phototoxicity study, oral administration of SRE (320 mg/kg) induced neither erythema nor edema. These results suggest that SRE is not antigenic or phototoxic.

Intralaboratory validation of alternative endpoints in the murine local lymph node assay for the identification of contact allergic potential: primary ear skin irritation and ear-draining lymph node hyperplasia induced by topical chemicals.

We validated a two-tiered murine local lymph node assay (LLNA) with a panel of standard contact (photo)allergens and (photo)irritants with the aim of improving the discrimination between contact (photo) allergenic potential and true skin (photo)irritation potential. We determined ear weights to correlate chemical-induced skin irritation with the ear-draining lymph node (LN) activation potential. During tier I LLNAs, a wide range of concentrations were applied on three consecutive days to the dorsum of both ears. Mice were exposed to UVA light immediately after topical application to determine the photoreactive potential of some test chemicals. Mice were killed 24 h after the last application to determine ear and LN weights and LN cell counts. It was possible to classify the tested chemicals into three groups according to their threshold concentrations for LN activation and skin irritation: (1) chemicals with a low LN activation potential and no or very low skin irritation potential; (2) chemicals with a marked LN activation potential higher than a distinct skin irritation potential; and (3) chemicals with LN activation potential equal to or lower than their skin irritation potential. Group 1 consisted only of contact allergens, indicating that LN activation in the absence of skin irritation points to a contact allergenic activity. Since groups 2 and 3 comprised irritants and contact allergens, a tier II LLNA protocol was used to finally differentiate between true irritants and contact allergens. Briefly, mice were pretreated with mildly to moderately irritating concentrations of the chemical to the shaved back and after 12 days were challenged on the ears as described above in order to elicit a contact allergenic response in the ear skin and the ear-draining LN. With this approach, tier II LLNAs have to be conducted only in cases for which skin irritation potential is in the range of LN activation potential and no structure-activity relationship data indicating a contact allergenic hazard are available.

Lymphocyte stimulation test with drug-photomodified cells in patients with quinolone photosensitivity.

Quinolone antibacterial agents, known to elicit photosensitive dermatitis as an adverse effect, have both phototoxicity and photoallergenicity. The latter potency is mainly derived from their photohaptenic moiety; quinolones covalently bind to protein and cells upon exposure to ultraviolet A (UVA) light. Our previous study has shown the in vivo and in vitro antigenicity of quinolone-photomodified cells in mice. Here, we examined the presence of sensitized lymphocytes that react with quinolone-photomodified autologous cells in patients with photosensitivity to quinolones. A flow cytometric analysis using a monoclonal antibody specific to quinolone photoadducts demonstrated that peripheral blood mononuclear cells (PBMC) were successfully photomodified with quinolones upon exposure to UVA. PBMC from quinolone-photosensitive patients were cocultured with autologous PBMC photomodified with the causative drug. Modest but significant proliferative responses of responder lymphocytes were found in patients photosensitive to lomefloxacin, fleroxacin, and enoxacin, indicating photoallergic mechanism in these patients. On the other hand, sparfloxacin-photosensitive patients exhibited negative lymphocyte stimulation test, suggesting that its photosensitivity is mainly phototoxic. When UVA-preirradiated quinolones were used as stimulators, only fleroxacin exceptionally stimulated patients' PBMC, indicating its prohaptenic as well as photohaptenic properties. These findings suggest the presence of circulating sensitized T cells in patients with photosensitivity to certain quinolones.

Effect of soluble complement receptor type 1 on porphyrin-induced phototoxicity in guinea pigs.

The effect of recombinant human soluble complement receptor type 1 (sCR1) on the porphyrin-mediated phototoxic reaction was evaluated in guinea pigs. Phototoxicity was induced in the animals by intraperitoneal injection of hematoporphyrin derivative (HpD), followed by irradiation at a wavelength range of 320-450 nm. sCR1 administration decreased CH50 titers in a dose-dependent fashion, while it only moderately suppressed HpD/radiation-induced ear swelling at a high dose. These findings suggest that phototoxic dermatological changes in cutaneous porphyrias are not solely due to complement activation.

[Phototoxicity and photoallergy]. / Fototoksisitet og fotoallergi.

As phototoxic and photoallergic reactions have been recognised as unwanted skin manifestations caused by any of several hundred substances, drugs and chemicals, it is essential to determine the potential photo-sensitising properties of such substances before they are introduced in clinical therapy or made available on the market, in order to avoid such reactions. In cases of phototoxic reactions, the patient presents with skin changes resembling sunburn, sometimes accompanied by blistering, whereas in cases of photoallergic reactions the skin changes are similar to those of allergic contact dermatitis. The two most important aids to clinical investigation are determination of the erythema treshold, or the minimal erythema dose, and photopatch testing. The article reviews the basic mechanisms of photosensitisation, outlining the most important differences between phototoxic and photoallergic reactions, summarises the most frequent photosensitisers, and presents the diagnostic procedures, including the tests used in experimental phototoxicity.

Comparative studies on the tolerance to photoinduced cutaneous inflammatory reactions by psoralen and rose bengal.

The photochemotherapeutic value of topical 8-methoxypsoralen (8-MOP) plus UVA irradiation has been well recognized. The phototoxicity associated with psoralen plus UVA (PUVA) therapy is hallmarked by an increase in vascular permeability (iVP), the accumulation of polymorphonuclear leukocytes (aPMN) and erythema formation in situ. Rose bengal (RB) plus UVA-VIS light (320-700 nm) produces a similar acute inflammatory response, but without immediate or delayed erythema and perceptible edema. This study describes some of the parameters involved in inflammatory reactions evoked by PUVA and the results are compared with RB-induced phototoxic reactions. The rates of iVP and aPMN with a 3 h pulse were quantified using 125I-albumin and 51Cr-labelled PMNs respectively. The erythemal response was graded visually. 8-MOP cream was applied topically, while RB was injected intradermally in rabbit skin before UVA-VIS (9.4 J cm-2) irradiation. The data show that there is no significant difference in the rates of iVP, aPMN and erythema formation between normal skin sites and mast cell-depleted skin sites when challenged with 8-MOP plus light. These results suggest that in situ mast cells do not play a significant role in 8-MOP-photoinduced acute cutaneous inflammatory reactions, in contrast with RB-photoinduced reactions. The iVP and aPMN responses are minimal or absent in sites subjected to repeated exposure to 8-MOP plus light for three or more consecutive days, suggesting the establishment of a desensitized/unresponsive state. Moreover, 8-MOP-photo-desensitized sites do not produce iVP and aPMN of the same magnitude as the normal (naive) skin sites when challenged with RB plus light. Similarly, RB-photo-desensitized sites do not produce iVP and aPMN of the same magnitude as the native skin sites when challenged with 8-MOP plus light. The desensitization and cross-desensitization of skin sites to 8-MOP- or RB-photoinduced reactions suggest that there is either direct attack on the target cell(s), thereby removing the ability to express adhesion molecules, such as endothelial leukocyte adhesion molecule 1 (ELAM-1) or intercellular adhesion molecule 1 (ICAM-1), involved in the accumulation of inflammatory cells, or downregulation of the secretion/release of putative agent(s), such as interleukin 1 (IL-1) and tumor necrosis factor alpha (TNF-alpha), responsible for the initiation and progression of cutaneous inflammations.

Detection of circulating T cells with CD4+CD7- immunophenotype in patients with benign and malignant lymphoproliferative dermatoses.

BACKGROUND: Cutaneous T-cell lymphomas (CTCLs) are malignancies of CD4+ T cells that involve the skin. CD4+CD7- cells may represent a malignant population in CTCL. OBJECTIVE: Our purpose was to compare the percentage of CD4+CD7- cells and the expression of pan-T-cell antigens in blood lymphocytes from 31 patients with benign dermatoses with 35 patients who had CTCL. METHODS: The patients with CTCL were classified as follows: 10 with mycosis fungoides (MF), seven with pre-Sézary syndrome (pre-SS), and 18 with Sézary syndrome (SS). Flow cytometry was used to determine the percentage of CD4+CD7- cells and the CD4/CD8 ratio and to detect aberrant expression of the pan-T-cell antigens CD2, CD3, and CD5. RESULTS: We found a mean of 5.8% CD4+CD7- cells for the 16 normal control subjects and 9.3% for the benign cases (p = 0.13). The patients with pre-SS and SS had a higher percentage of CD4+CD7- cells (22.4% and 35.5%, respectively) than patients with benign dermatoses (p < 0.01); no difference was found between patients with benign dermatoses and those with MF (p = 0.80). The mean CD4/CD8 ratio was 3.1 for the normal control subjects compared with 7.4 for the patients with benign dermatoses (p < 0.01). Patients with SS had a ratio of 49, which was higher than the ratio for those with benign dermatoses (p < 0.01); however, the ratio for patients with MF and pre-SS did not differ from that of the group with benign dermatoses (p = 0.71 and 0.55, respectively). Aberrant CD2, CD3, or CD5 expression was observed in 66% of patients with SS, 29% with pre-SS, 30% with MF, but in none of the patients with a benign dermatosis. CONCLUSION: Small numbers of CD4+CD7- cells can be found by flow cytometry in patients with a benign dermatosis and in normal control subjects. This T-cell subset is expanded in pre-SS and SS but not in MF. Aberrant pan-T-cell antigen expression is commonly observed in patients with SS but not in patients with a benign dermatosis.