The cellular inflammatory response in nicotinate skin reactions

Sequential skin biopsies of nicotinate-treated skin from nine normal subjects, three aspirin-pretreated normal subjects and six atopic eczema patients were examined. An erythematous skin reaction was seen in the nine normal subjects and to a lesser degree in one atopic eczema patient, but not in the aspirin-pretreated subjects nor in five remaining atopics. Accumulation of a mononuclear cell perivascular infiltrate was seen from 15 min onwards in the normal subjects. Neutrophils became the predominant cell invading thickened vessel walls and in the perivascular space beginning at 2 h and persisting up to 48 h. Leucocytoclasis was observed at 24 h. Immunofluorescence studies showed only non-specific fibrinogen deposits in papillary capillaries in the three groups of subjects. The chloroacetate esterase reaction and immunohistochemical labelling with OKM I confirmed a marked neutrophilia at 2 h and 24 h. Neutrophils were seen in one atopic eczema patient, but were not observed in the remainder, nor in the skin of the aspirin-pretreated normal subjects. Topical application of nicotinate causes non-allergenic, leucocytoclastic vascular damage in normal skin which can be inhibited by aspirin and which is reduced or absent in atopic eczema.     

An immunopathological study of herpes-associated erythema multiforme

Any pathogenetic mechanism proposed for erythema multiforme (EM) must account for the prominent mononuclear cell infiltrate in the skin lesions. The purpose of this study was to characterize immunopathologically, with monoclonal antibodies to human leukocyte antigens, the inflammatory cells in early target lesions of recurrent herpes-associated EM. Cryostat sections of snap-frozen skin biopsies were studied by the avidin-biotin immunoperoxidase technique with use of the following monoclonal antibodies: anti-HLA-DR, anti-Leu M5, anti-Leu 4 + 5b, anti-Leu 3a + 3b, anti-Leu 2a, anti-Leu 14, and anti-Leu 6. The dermal mononuclear inflammatory infiltrate in the EM biopsies consisted of monocyte-macrophages and T-lymphocytes, with both helper and suppressor T cells present. Both the dermal inflammatory infiltrate and the overlying keratinocytes were strongly HLA-DR positive. No definite alteration of Langerhans cell number or distribution was noted. These findings are consistent with the characteristics seen in cell-mediated immune reactions in the skin and point to this as a likely immune mechanism for the tissue damage of EM.     

Topical aminolaevulinic acid-photodynamic therapy produces an inflammatory infiltrate but reduces Langerhans cells in healthy human skin in vivo

Background Topical photodynamic therapy (PDT) elicits a therapeutic response in both skin cancer and immune‐mediated skin disorders. While PDT induces direct cell death, host inflammatory and immune responses to PDT may contribute to the therapeutic effects. Objectives To examine the impact of topical PDT on leucocyte trafficking and mediators of chemotaxis in healthy human skin. Methods Aminolaevulinic acid (ALA)‐PDT was performed on the buttock skin of seven healthy volunteers. Biopsies for immunohistochemical assessment were taken 1, 4 and 24 h post‐PDT and from untreated contralateral buttock skin (baseline). Results A significant dermal neutrophilic infiltrate appeared early, peaking at 4 h (P < 0·01) and returning to near baseline by 24 h. Expression of E‐selectin was significantly higher at 4 h (P < 0·05) and correlated strongly with neutrophil numbers (r = 0·93). Expression of intercellular adhesion molecule 1 was significantly elevated after 24 h (P < 0·05) with an apparent gradual increase in CD4+ T cells up to this time point. Notably, epidermal Langerhans cells were significantly reduced 24 h post‐PDT compared with baseline (P < 0·01) and comprised a significantly larger proportion of cells with migratory rather than dendritic morphology (P < 0·05). The number of epidermal cells expressing tumour necrosis factor‐α significantly increased at 4 h (P < 0·05) and remained elevated 24 h post‐PDT, whereas no significant change in expression of interleukin (IL)‐1β or IL‐8 was seen. Conclusions Reduction of Langerhans cells by topical PDT of human skin may play a significant role in PDT‐induced local immunosuppression, potentially benefiting the treatment of immune‐mediated skin disorders but negatively impacting on antitumour responses. Further exploration according to disease indication/treatment protocol is warranted.     

Immunohistology of skin pathergy reaction in Behçet's disease

Summary The immunophenotypic characteristics of the skin pathergy reaction (SPR) at 48 h in Behçet's disease (BD) were investigated in 12 patients with BD and in five controls. The findings in 11 positive and one negative SPR lesions of patients with BD were evaluated in comparison with those of normal adjacent skin and with the negative pathergy biopsies from the controls. Positive SPR biopsies showed variable epidermal thickening and cell vacuolization, as well as subcorneal pustule formation. In the SPR dermis, a variable dense focal mononuclear cell (MNC) infiltrate was seen around vessels and skin appendages, extending into the deep dermis. The MNC infiltrate was predominantly composed of T lymphocytes and monocytes/macrophages. The majority of the T lymphocytes were CD4⁺, and almost all expressed CD45RO. Approximately half of the infiltrating cells strongly expressed HLA-DR. Neutrophils constituted less than 5% of the infiltrating cells, but were present as clusters of elastase-positive cells at the needle-prick sites. Vessels within the lesion showed marked congestion and endothelial swelling. The endothelial cells expressed ICAM-1 strongly, and E-selectin moderately. VCAM-1 was not expressed on endothelial cells. The basal and mid-epidermal layers of keratinocytes expressed HLA-DR and ICAM-1 strongly, particularly so in areas close to the dermal MNC infiltrates. In negative pathergy biopsies, there were increased numbers of neutrophils and a few small clusters of macrophages and T lymphocytes only at the needle-prick site, and the endothelial cells of vessels close to these areas expressed E-selectin weakly. The immunohistological findings of the SPR appear to indicate an augmented antigen-independent non-specific induction phase of the inflammatory response. Absence of VCAM-1 expression by endothelial cells suggests that direct epidermal injury is the cause of the cutaneous inflammation.     

Mononuclear cell stimulation of fibroblast collagen synthesis

Accumulating evidence suggests that there may be a relationship between inflammatory responses and enhanced collagen synthesis in certain skin diseases. In our experiments, unstimulated normal human lymphocytes and phytohaemagluttinin (HA-17) stimulated lymphocytes were cultured for 72 h and then added to normal human foreskin fibroblast monolayer cultures. The various groups tested included medium and sera alone, medium and lymphocytes ± HA-17, and HA-17 alone. Five to 10 μCi of (2, 3-³H)-proline were added to each monolayer containing 2·5-3·5 × 10⁶ fibroblasts along with cultured lymphocytes, HA-17 alone, or HA-17 cultured lymphocytes. After an incubation period (pulse) of 24 h ³H hydroxyproline was separated and assayed using a modification of the method of Switzer & Summer (1971). The conversion of ³H proline to ³H hydroxyproline was used as a measure of collagen synthesis. The results demonstrated that the addition of unstimulated cultured lymphocytes stimulated fibroblast collagen synthesis. HA-17 alone is also capable of stimulating collagen synthesis in vitro. The greatest stimulation (counts/min ³H hydroxyproline) was seen when fibroblasts were incubated with lymphocytes previously activated by HA-17. These results are consistent with the hypothesis that activated mononuclear cells may stimulate collagen synthesis by fibroblasts in vivo in such diseases as scleroderma and chronic graft-versus-host disease.     

Can St John's wort (hypericin) ingestion enhance the erythemal response during high‐dose ultraviolet A1 therapy?

Background St John's wort (SJW) is widely used as a treatment for depression. A phototoxic reaction, due to its content of hypericin, can occur in animals and in cell culture, and has been reported in humans. Hypericin displays absorption within the ultraviolet (UV) A1 spectrum and there may therefore be a potential for phototoxicity if taken during high‐dose UVA1 therapy. Objectives To assess the phototoxicity risk of SJW ingestion. Methods Eleven adult volunteers of skin types I and II were exposed to a geometric dose series of UVA1 irradiation from a high‐output source (Dermalight Ultra 1; Dr Hönle, Martinsreid, Germany; irradiance 70–77 mW cm^?2) on the photoprotected lower back skin at eight 1·5‐cm² test areas. Irradiation was carried out at baseline and after 10 days of SJW extract 1020 mg (equivalent to 3000 µg of hypericin) daily. Four, 8, 24 and 48 h after each exposure, the minimal erythema dose (MED) and the presence or absence of pigmentation were recorded visually and erythema was assessed objectively with an erythema meter. Results The median MED and D_0·025, an objective measure of MED, were lower at all time‐points after SJW ingestion. The visual erythemal peak (lowest median MED), which was seen at 8 h postirradiation, was lower after SJW (median 14 J cm^?2, range 10–56) than at baseline (median 20 J cm^?2, range 14–56) (P = 0·047). Similarly, the median D_0·025 at 8 h postirradiation was lower after SJW (median 22·0 J cm^?2, range 15·2–53·9) than at baseline (median 33·7 J cm^?2, range 22·9–136·0) (P = 0·014). The MED and D_0·025 were also significantly different at the 48‐h and 4‐h time‐points, respectively. Significance was not reached at the 24‐h time‐point. Median intensity of postirradiation erythema increased at all time‐points after ingestion of SJW. Despite these differences, the maximum slope of the dose–response curve was not increased after SJW ingestion. Conclusions These data suggest that SJW extract has the potential to lower the erythemal threshold to UVA1 irradiation in a significant proportion of individuals and highlight the importance of ascertaining a full drug history, including herbal remedies, before initiating UVA1 phototherapy.     

COMPARATIVE STUDY OF 3H-THYMIDINE LABELLING OF THE DERMAL INFILTRATE OF SKIN ALLERGIC AND IRRITANT PATCH TEST REACTIONS IN MAN

The ³H-Thymidine (³HT) nuclear labelling index of “round” cells of the dermal infiltrate in allergic and irritant patch test reactions in man has been compared. The skin of 15 positive allergic patch test reactions (to different allergens) and of 15 positive irritant reactions (5 to croton oil, 5 to potassium hydroxide and 5 to white spirit) was biopsied 48 hours after the application of the chemical. Thin slices of each specimen were incubated for 60 min in the presence of ³HT. then fixed and prepared for light microscopy radioautography. Two thousand “round” cells of the infiltrate were counted in each specimen. The mean values of the ³HT labelling indices (±S.E.) were 2·91±0·18%, in the allergic group and 0·58 ± 0·06% in the irritant group. The difference between the 2 means was highly significant (P < 0.01). There was no significant difference between the labelling indices of the 3 irritants (P > 0.05). All the labelled cells were mononucleated. This method could be useful to differentiate clinically dubious allergic and irritant reactions.     

Comparison of changes in endothelial adhesion molecule expression following UVB irradiation of skin and a human dermal microvascular cell line (HMEC-1)

We have assessed the pattern of dermal endothelial adhesion molecule expression following broadband UVB irradiation in vivo and in vitro. Skin biopsies were taken from 4 human volunteers at baseline and at 4, 8 and 24 h post-irradiation with 2.5 minimal erythema doses of UVB. Sections were stained immunohistochemically for E-selectin, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), CD31 and neutrophil elastase. The effect of direct UVB irradiation on E-selectin, ICAM-1 and VCAM-1 was examined in a human dermal microvascular endothelial cell line, HMEC-1. Cultured HMEC-1 were irradiated with 2.5–40 mJ/cm² of UVB, and assessed for adhesion molecule expression by immunofluorescence microscopy and fluorescence-activated cell sorter analysis. In vivo, E-selectin was minimally expressed on EC at baseline and was induced by 4 h following irradiation, P<0.01. ICAM-1 was moderately expressed at baseline and appeared mildly induced at 24 h, although this did not reach statistical significance. VCAM-1 was weakly expressed in unirradiated skin while CD31 was moderately expressed, but neither was induced by UVB irradiation. A significant neutrophilic infiltrate appeared by 8 h and was maximal at 24 h, P<0.05. Neutrophil infiltration correlated with E-selectin expression, r=0.96. In HMEC-1, ICAM-1 was upregulated at 24 h post-irradiation, with an increase in mean channel fluorescence from 100% at baseline to 145 (SD12)%> at 24 h, P<0.05. No change was seen in expression of E-selectin, VCAM-1 or CD31. These studies support the involvement of endothelial adhesion molecules E-selectin and ICAM-1 in UVB-induced inflammation. Whereas ICAM-1 is upregulated by direct irradiation of endothelial cells, E-selectin stimulation appears to be an indirect effect.     

Clothing reduces the sun protection factor of sunscreens

Background Individuals are recommended to wait for 20 min following sunscreen application before dressing. However, this is probably seldom done in daily life, and therefore we investigated how dressing earlier than 20 min after application affected the sun protection factor (SPF). Objectives To determine the SPF of a sunscreen applied at different amounts at 4, 8 and 20 min before dressing. Methods An organic sunscreen was used on the backs of 22 healthy volunteers. Before SPF testing, participants wore a cotton T‐shirt for 60 min after the test areas had been uncovered for 4, 8 or 20 min after sunscreen application. The SPF was also tested on unclothed skin. Results The median SPF was 11·7 (2 mg cm^?2), 5·7 (1 mg cm^?2) and 3·3 (0·5 mg cm^?2) for unclothed skin, and 8·1 (2 mg cm^?2), 4·8 (1 mg cm^?2) and 2·2 (0·5 mg cm^?2) following an interval of 8 min before dressing. The SPF was similar for time intervals of 20 and 8 min when the amount was 1 mg cm^?2 (P = 0·48) and 2 mg cm^?2 (P = 0·56). For 0·5 mg cm^?2 there was no difference between skin clothed after 20 min and unclothed skin (P = 0·19), nor between skin clothed after 4 min and after 8 min (P = 0·28). Conclusions When sunscreens are applied at amounts of 1 and 2 mg cm^?2 the time between sunscreen application and dressing can be as little as 8 min. When less sunscreen is used the SPF is insensitive to the length of time between application and dressing.     

Photoprotective potential of Cordyceps polysaccharides against ultraviolet B radiation-induced DNA damage to human skin cells

Summary Background Ultraviolet (UV) radiation causes DNA damage resulting in photoageing and skin cancer. UVB (290–320 nm) interacts directly with DNA, inducing two major photoproducts: cyclobutane‐pyrimidine dimers (CPDs) and (6‐4) pyrimidine‐pyrimidone photoproducts. Cordyceps sinensis (Berk.) Sacc. is a medicinal fungus with reported anticancer and cytoprotective effects. Objectives To investigate genoprotective effects of polysaccharide‐rich Cordyceps mycelial components against UVB‐induced damage in normal human fibroblast cells. Methods Cultured human fibroblasts (BJ cells) were treated for 30 min and, separately, for 24 h with hot water extract of Cordyceps fungal mycelia or exopolysaccharides. Cells were washed, irradiated with UVB (302 nm), and immediately lysed, after which DNA damage, as strand breaks, was measured using an enzyme‐assisted comet assay that detects CPDs. Results DNA damage in UVB‐irradiated cells was significantly lowered (P < 0·01) with Cordyceps pretreatment. Similar results were seen with 30 min and 24 h pretreatment. Specifically, and in comparison with irradiated cells with no Cordyceps pretreatment, there was a 27% reduction in CPDs in irradiated cells with 24 h pretreatment with 200 μg mL^?1 of the hot water Cordyceps extract, and a 34% reduction with 24 h pretreatment with 200 μg mL^?1 of the exopolysaccharide extract. Conclusions Clear evidence of protection against UVB‐induced CPDs was seen with Cordyceps mycelial extracts. Results indicate that Cordyceps may offer photoprotection and lower the risk of basal cell carcinoma, the main skin cancer caused by CPDs. Further study is needed to identify protective mechanisms.     

Adhesion molecule expression in polymorphic light eruption.

Endothelial leukocyte adhesion molecule-1 (ELAM-1), vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1) are cytokine-regulated cell-surface leukocyte adhesion molecules. We have investigated the in vivo kinetics and pattern of expression of these adhesion molecules in relation to tissue accumulation of leukocytes in the photodermatosis, polymorphic light eruption (PMLE), which is characterized by dense perivascular leukocytic infiltration. Immunohistology was performed on biopsies taken at varying time points from PMLE lesions induced in 11 subjects by suberythemal solar simulated irradiation. Vascular endothelial ELAM-1 expression was first observed at 5 h, maximal at 24 to 72 h, and remained elevated at 6 d. VCAM-1, minimally expressed in control skin, was induced above background levels on endothelium and some perivascular cells after 24 h and maintained at 6 d. Endothelial cell ICAM-1 expression was increased above control levels at 72 h and 6 d. Keratinocyte ICAM-1 expression, most marked overlying areas of dermal leukocytic infiltration, began at 5 h and was strong at 72 h and 6 d. In addition to lymphocytes, significant numbers of neutrophils but not eosinophils were detected in the dermal leukocytic infiltrate that appeared at 5 h and persisted at 6 d. The pattern of adhesion molecule expression that we have observed is similar to that seen in normal skin during a delayed hypersensitivity reaction. These observations support an immunologic basis for PMLE.     

Itch and inflammation induced by intradermally injected interleukin-2 in atopic dermatitis patients and healthy subjects

To explore the pruritogenic and inflammatory effects of cytokines, a single dose of 20 g recombinant human interleukin-2 was injected intradermally into eight patients with atopic dermatitis and eight healthy controls. The study was double-blind and randomized with glucose as a negative control. The effects were evaluated by recording local itch and erythema over 72 h and by examining skin biopsies taken at 24 h and 72 h. In patients and controls, interleukin-2 provoked a low-intensity local itch with maximal intensity between 6 h and 48 h and erythema with maximal extension between 12 h and 72 h. In the atopic dermatitis patients, these reactions tended to appear earlier and were less pronounced than in the healthy controls. Interleukin-2 induced dermal mononuclear cell infiltrates consisting mainly of CD3⁺ cells. A majority of the T cells were CD4⁺. The number of dermal CD25⁺, HLA-DR⁺ and ICAM-1⁺ cells was also increased at the interleukin-2 injection sites. In the epidermis, interleukin-2 induced spongiosis and exocytosis as well as HLA-DR⁺ and ICAM-1⁺ keratinocytes. The microscopic findings tended to be more prominent at 72 h than at 24 h in both groups, but with a somewhat slower onset in the atopic dermatitis patients. In conclusion, a single intradermal injection of interleukin-2 induced local itch, erythema, dermal T-cell infiltrates, spongiosis, exocytosis and activation of keratinocytes both in atopic dermatits patients and in healthy controls.     

Adhesion molecule expression and the inflammatory cell infiltrate in delayed pressure urticaria

We have investigated the kinetics of the leucocyte infiltrate in delayed pressure urticaria (DPU) in relation to the in vivo expression of the cytokine-regulated cell surface adhesion molecules. E-selectin (endothelial adhesion molecule-1. ELAM-1). intercellular adhesion molecule-1 (ICAM-1), and vascular adhesion molecule-1 (VCAM-1). Immunohistochemical analysis was performed on biopsies taken from unchallenged skin, and at 0, 2, 6, 24, 48 and 120 h after weighted rods had been applied to 13 patients with DPU. There was moderate to marked upregulation of E-selectin at 6 and 24 h after application of pressure. At 24 h, more patients showed expression of VCAM-1 on perivascular cells than before pressure. Moderate expression of ICAM-1 was present in some biopsies from both unchallenged and pressure-challenged skin, but there was no clear trend. In DPU, there was a significant increase in the neutrophil count at 2 h after a pressure challenge, with further increases at 6 and 24 h. The median cell counts per high-power field of eosinophils and monocyte/ macrophages increased significantly at 24 h after pressure. Biopsies from four normal controls subjected to an identical pressure challenge showed no detectable changes in adhesion molecule expression or in the cell infiltrate. The findings in four patients with chronic idiopathic urticaria not associated with DPU were qualitatively similar to (but intermediate in severity between) the findings in DPU weals at 6 and 24 h. These results suggest that vascular endothelial activation is an early response to pressure challenge in DPU, and is also present in chronic idiopathic urticaria. The inflammatory infiltrate in DPU differs in intensity, but not in composition, from that in chronic idiopathic urticaria.     

A histological and immunocytochemical study of early acne lesions

We examined 69 biopsies of acne lesions known to be 6, 24 or 72 h old and found that the lymphocyte was the predominant cell at 6 and 24 h. The helper:suppressor T cell ratio in the inflammatory infiltrate was 2.8:1. Polymorphonuclear leukocytes were increasingly seen at 24 and 72 h and were associated with disruption of the duct. We hypothesize that this early lymphocytic infiltrate represents a cell mediated immune response to an antigen within the duct lumen.     

Topical sodium cromoglicate relieves allergen‐ and histamine‐induced dermal pruritus

Background Sodium cromoglicate (SCG) has long been used in the management of allergic diseases, including as an ointment for atopic dermatitis. Although mast cell stabilization was initially considered as its mechanism of action, anti‐inflammatory actions and modulation of sensory nerve function have also been suggested. Objectives To investigate the mechanism(s) by which SCG relieves allergen‐ and histamine‐induced dermal inflammation by assessing its effects on pruritus, flare, skin temperature and weal volume. Methods Aqueous cream containing 0·2%, 1% or 4% SCG or no SCG (placebo) was applied in a randomized single‐blind manner to four areas on each forearm (two sites per arm) and covered with an occlusive dressing. One hour later, skin‐prick tests were performed in 20 allergic subjects with allergens to which they had previously shown sensitization, and in 40 nonallergic subjects with codeine (9 mg mL^?1, 20 subjects) and histamine (10 mg mL^?1, 20 subjects). Weal volume, skin temperature increase, erythema area and pruritus intensity were assessed at 0, 5, 10 and 15 min. Results SCG significantly (P < 0·05 to P < 0·001) reduced pruritus induced by all stimuli, with 4% SCG being most effective. Significant (P < 0·05 to P < 0·01) reductions of erythema area were also seen but there was no inhibition of weal volume or temperature increase. Conclusions SCG is effective in reducing pruritus but has no effect on weals, supporting the proposition that, in the skin, SCG inhibits sensory C‐fibre nerve activation rather than preventing mast cell degranulation. We suggest that topical SCG treatment, delivered in an appropriate vehicle, may be beneficial for symptomatic relief of pruritus in patients with cutaneous mastocytosis and other pruritic dermatoses.     

Tomato paste rich in lycopene protects against cutaneous photodamage in humans in vivo: a randomized controlled trial

Background Previous epidemiological, animal and human data report that lycopene has a protective effect against ultraviolet radiation (UVR)‐induced erythema. Objectives We examined whether tomato paste – rich in lycopene, a powerful antioxidant – can protect human skin against UVR‐induced effects partially mediated by oxidative stress, i.e. erythema, matrix changes and mitochondrial DNA (mtDNA) damage. Methods In a randomized controlled study, 20 healthy women (median age 33 years, range 21–47; phototype I/II) ingested 55 g tomato paste (16 mg lycopene) in olive oil, or olive oil alone, daily for 12 weeks. Pre‐ and postsupplementation, UVR erythemal sensitivity was assessed visually as the minimal erythema dose (MED) and quantified with a reflectance instrument. Biopsies were taken from unexposed and UVR‐exposed (3 × MED 24 h earlier) buttock skin pre‐ and postsupplementation, and analysed immunohistochemically for procollagen (pC) I, fibrillin‐1 and matrix metalloproteinase (MMP)‐1, and by quantitative polymerase chain reaction for mtDNA 3895‐bp deletion. Results Mean ± SD erythemal D₃₀ was significantly higher following tomato paste vs. control (baseline, 26·5 ± 7·5 mJ cm^?2; control, 23 ± 6·6 mJ cm^?2; tomato paste, 36·6 ± 14·7 mJ cm^?2; P = 0·03), while the MED was not significantly different between groups (baseline, 35·1 ± 9·9 mJ cm^?2; control, 32·6 ± 9·6 mJ cm^?2; tomato paste, 42·2 ± 11·3 mJ cm^?2). Presupplementation, UVR induced an increase in MMP‐1 (P = 0·01) and a reduction in fibrillin‐1 (P = 0·03). Postsupplementation, UVR‐induced MMP‐1 was reduced in the tomato paste vs. control group (P = 0·04), while the UVR‐induced reduction in fibrillin‐1 was similarly abrogated in both groups, and an increase in pCI deposition was seen following tomato paste (P = 0·05). mtDNA 3895‐bp deletion following 3 × MED UVR was significantly reduced postsupplementation with tomato paste (P = 0·01). Conclusions Tomato paste containing lycopene provides protection against acute and potentially longer‐term aspects of photodamage.     

Longwave ultraviolet radiation (UVA, 320-400 nm)-induced tan protects human skin against further UVA injury

The protective effect of a UVA (320-400 nm) induced tan against cutaneous injury by further UVA-irradiation was studied by evaluating the histopathologic changes in tanned and untanned normal human buttock skin 24 h after exposure to 2 and 4 minimal erythema doses of UVA. In each subject there were fewer polymorphonuclear leukocytes and less endothelial cell prominence and vessel wall necrosis in the UVA tanned skin than in the untanned UVA-irradiated skin. In the tanned control and tanned UVA-irradiated skin there was a prominent mononuclear cell inflammatory infiltrate that was much greater than in untanned skin. In immunoperoxidase stained tissue sections, the mononuclear cells were predominantly T cells, and in all of the specimens the number of phenotypic helper/inducer cells exceeded the phenotypic cytotoxic/suppressor cells. This demonstrates that a UVA tan provides photoprotection against acute UVA exposure. In addition, tanning, with or without further UVA-irradiation, was associated with a mononuclear cell inflammatory infiltrate.     

Immunophenotype of skin lymphocytic infiltrate in patients co-infected with Mycobacterium leprae and human immunodeficiency virus: a scenario dependent on CD8+ and/or CD20+ cells

Background Leprosy occurs rarely in human immunodeficiency virus (HIV)‐positive patients. In contrast to tuberculosis, there has been no report to date of an increase in HIV prevalence among patients with leprosy or of differences in leprosy’s clinical spectrum. While several studies describe the systemic immune response profile in patients co‐infected with HIV and leprosy, the local immune skin response has been evaluated in only a small number of case reports and limited series of patients. Objective To investigate the interaction between Mycobacterium leprae and HIV infection in the skin. Methods We investigated the presence and frequency of cells positive for CD4, CD8, CD20, TIA‐1, FOXP3 and CD123 in lymphocytic infiltrates from 16 skin biopsies taken from 15 patients with HIV–leprosy co‐infection. Results CD4+ cells were absent in infiltrates from 6 (38%) skin biopsies and present in 10 (62%) cases at low levels (< 1·16%) of the lymphocytic infiltrate. CD8+ was the predominant phenotype in the infiltrate (99·4%), followed by TIA‐1, expressed by > 75% of CD8+ cells. FOXP3+ cells were also present, representing 3·4% of the lymphocytic infiltrate. CD20+ cells were detected in 75% of the cases; however, in two cases (12%) these cells represented 25–50% of the infiltrate, while in the other 10 cases (62%) they were present only focally (< 25% of the infiltrate). CD123+ cells were not observed in any of the studied specimens. Conclusions Data presented here suggest that cell‐mediated immune responses to M. leprae are preserved at the site of disease and that in the absence of CD4+ cells, CD8+FOXP3+ and CD20+ cells may be involved in granuloma formation.     

The disturbance of epidermal barrier function in atopy patch test reactions in atopic eczema

Summary Atopic eczema (AE) is a common skin disorder. Eczematous lesions showing macroscopic, microscopic and immunopathological resemblance to lesional AE can be induced by aeroallergens by epicutaneous testing (atopy patch test, APT). Altered epidermal barrier function, as determined by transepidermal water loss (TEWL), is a typical feature of patients with AE. The present investigation was performed to define the differences in the epidermal barrier function between positive APT reactions to aeroallergens and positive patch test reactions to contact allergens in AE patients. Allergen extracts from grass pollen, birch pollen, cat dander and house dust mite (Dermatophagoides pteronyssinus) were applied in large Finn chambers on Scanpor for 48h on the clinically unaffected and untreated skin of the back, in 11 patients with AE. The same procedure was done with 27 contact allergens of a standard test battery. Test reactions were read and TEWL was measured after 48 and 72h. Eight of the 11 patients developed positive APT reactions toD. pteronyssinus, two to cat dander and one to birch pollen. Seven of the 11 patients showed positive patch test reactions to nickel sulphate, two to potassium dichromate, one to thiuram-mix and one to paraphenylenediamine. Vehicle controls were negative. The TEWL of the positive APT reactions was significantly higher, both after 48 h (mean ± standard deviation 10·0±6·5 g/m²h) and after 72 h (9·7±5·4g/m²h) as compared with the control site (48/72h: 4·4±1.5/4·1±1·4 g/m²h) (P<0·01). In contrast, TEWL of the positive patch test reactions to contact allergens (48/72h; 5·4±2·2/5·4±1·9g/m²h) was similar to that of the control site (48/72 h: 5·2±2·1/5·0± 1·8g/m²h) (not significant). The relative TEWL at 48 h and 72 h, expressed as the ratio between the positive patch test and the control site, was significantly higher in the positive APT reactions (48/72 h: 218·8±80·4%/232·0±85·9%) compared with positive patch test reactions to contact allergens (48/72 h: 102·1±12·0%/107·1±9·5%) (P<0·01). It is concluded that the epidermal barrier function in AE patients is altered only in positive APT reactions, in contrast to positive patch test reactions to contact allergens. As a consequence of this aeroallergen-induced altered epidermal barrier function, further allergens can more easily penetrate the skin, inducing a vicious circle and perpetuating the eczematous lesions.     

Characterization of skin cytokines in bullous pemphigoid and pemphigus vulgaris

The purpose of this study was to determine cytokine and cell marker expression in perilesional skin biopsies from patients with the autoimmune blistering diseases bullous pemphigoid (BP, n = 21) and pemphigus vulgaris (PV, n = 7). Immunohistochemistry and in situ hybridization were used to detect T helper (Th)1 [interleukin (IL)-2, interferon (IFN)-gamma] and Th2 (IL-4, IL-5, IL-13) protein and mRNA. Perilesional skin biopsies from patients with BP were characterized by the deposition of IL-4, IL-13 and IL-5. In patients with BP, IL-4 and IL-13 localized to mononuclear cells within the dermal infiltrate while IL-5 was predominately expressed at the dermal-epidermal junction. BP skin sections also expressed vascular cell adhesion molecule 1 on endothelial cells, not seen in patients with PV. PV biopsies were remarkable for a mixed Th1/Th2 pattern of cytokine expression, including the presence of IL-2, IFN-gamma and IL-4 and the absence of IL-5 and IL-13. In situ hybridization detected mRNA for IL-4 and IL-5 in the cellular infiltrate of BP patients, and IL-2 in a patient with PV. In vitro binding assays demonstrated that normal human eosinophils, activated by coculture in IL-5, bound preferentially to BP skin sections that contained detectable in vivo bound IL-5. The predominance of Th2 cytokines in BP, in association with increased binding of eosinophils in vitro, suggests that Th2 cytokines are relevant in the recruitment and adhesion of eosinophils within the dermal infiltrates of patients with BP, and may play a part in the pathogenesis of blister formation.