Ultrastructure: effects of melanin pigment on target specificity using a pulsed dye laser (577 nm)

It has been shown recently that brief pulses of 577 nm radiation from the tunable dye laser are absorbed selectively by oxyhemoglobin. This absorption is associated with highly specific damage to superficial vascular plexus blood vessels in those with lightly pigmented (type I-II) skin. To determine whether pigmentary differences in the overlying epidermis influence this target specificity, we exposed both type I (fair) and type V (dark) normal human skin to varying radiant exposure doses over 1.5-microsecond pulse durations from the tunable dye laser at a wavelength of 577 nm. Using ultrastructural techniques, we found in type I skin that even clinical subthreshold laser exposures caused reproducible alterations of erythrocytes and adjacent dermal vascular endothelium without comparable damage to the overlying epidermis. In contrast, degenerated epidermal basal cells represented the predominant form of cellular damage after laser exposure of type V skin at comparable doses. We conclude that epidermal melanin and vascular hemoglobin are competing sites for 577 nm laser absorption and damage, and that the target specificity of the 577 nm tunable dye laser is therefore influenced by variations in epidermal pigmentation. This finding is relevant to the clinical application of the tunable dye laser in the ablative treatment of vascular lesions. We also found on ultrastructure that the presence of electron-lucent circular structures of approximately 800 A in diameter were observed only at and above clinical threshold doses in those with type I skin and at the highest dose of 2.75 J/cm2 in type V skin. It has been proposed that these structures might be heat-fixed molds of water vapor. Both this and ultrastructural changes of epidermal basal cells demonstrate mechanisms responsible for alteration of tissue after exposure to 577 nm, which are discussed.     

Intravenous injection of indocyanine green to enhance laser‐assisted coagulation of blood vessels in skin – an animal study

Background Laser therapy of vascular lesions, such as port wine stains (PWS) or leg veins are still imperfect due to different diameters and depth of vessels in tissue. We propose to improve blood vessel coagulation by intravenous introduction of an exogenous chromophore (indocyanine green, ICG) that effectively converts near‐infrared (NIR) laser light into heat. Objective The purpose of this study was to determine the plasma clearance rate, systemic toxicity and histological effects of ICG‐assisted laser therapy in an animal model. Methods Piglets received intravenous injection of ICG. Blood samples were collected at different times. Systemic toxicity was assessed by measuring liver enzyme levels and other indicators of liver function. The plasma clearance rate of ICG was determined by light absorption measurement in blood samples. The skin was irradiated with a diode laser (810 nm) using radiant exposures from 31 to 80 J/cm². Skin reaction at the treatment site was graded, and punch biopsies were taken for histological examination at 24 and 72 h after treatment. Results No hepatic toxicity was observed. The clinical examination revealed no adverse skin reactions at 24 or 72 h after laser irradiation. This was confirmed by histological evaluation that showed efficient vessel coagulation without damage of the epidermis or dermis. Conclusions In light of these in vivo results, we suggest that ICG‐assisted laser therapy could substantially improve clinical outcomes of PWS or leg veins treatment with minimal risk of adverse reactions.     

Vascular lasers and IPLS: Guidelines for care from the European Society for Laser Dermatology (ESLD)

Dermatology and dermatologic surgery have rapidly evolved during the last two decades thanks to the numerous technological and scientific acquisitions focused on improved precision in the diagnosis and treatment of skin alterations. Given the proliferation of new devices for the treatment of vascular lesions, we have considerably changed our treatment approach. Lasers and non‐coherent intense pulse light sources (IPLS) are based on the principle of selective photothermolysis and can be used for the treatment of many vascular skin lesions. A variety of lasers has recently been developed for the treatment of congenital and acquired vascular lesions which incorporate these concepts into their design. The list is a long one and includes pulsed dye (FPDL, APDL) lasers (577?nm, 585?nm and 595?nm), KTP lasers (532?nm), long pulsed alexandrite lasers (755?nm), pulsed diode lasers (in the range of 800 to 900?nm), long pulsed 1064 Nd:YAG lasers and intense pulsed light sources (IPLS, also called flash‐lights or pulsed light sources). Several vascular lasers (such as argon, tunable dye, copper vapour, krypton lasers) which were used in the past are no longer useful as they pose a higher risk of complications such as dyschromia (hypopigmentation or hyperpigmentation) and scarring. By properly selecting the wavelength which is maximally absorbed by the target – also called the chromophore (haemoglobin in the red blood cells within the vessels) – and a corresponding pulse duration which is shorter than the thermal relaxation time of that target, the target can be preferentially injured without transferring significant amounts of energy to surrounding tissues (epidermis and surrounding dermal tissue). Larger structures require more time for sufficient heat absorption. Therefore, a longer laser‐pulse duration has to be used. In addition, more deeply situated vessels require the use of longer laser wavelengths (in the infrared range) which can penetrate deeper into the skin. Although laser and light sources are very popular due to their non‐invading nature, caution should be considered by practitioners and patients to avoid permanent side effects. These guidelines focus on patient selection and treatment protocol in order to provide safe and effective treatment. Physicians should always make the indication for the treatment and are responsible for setting the machine for each individual patient and each individual treatment. The type of laser or IPLS and their specific parameters must be adapted to the indication (such as the vessel's characteristics, e.g. diameter, colour and depth, the Fitzpatrick skin type). Treatments should start on a test patch and a treatment grid can improve accuracy. Cooling as well as a reduction of the fluence will prevent adverse effects such as pigment alteration and scar formation. A different number of repeated treatments should be done to achieve complete results of different vascular conditions. Sunscreen use before and after treatment will produce and maintain untanned skin. Individuals with dark skin, and especially tanned patients, are at higher risk for pigmentary changes and scars after the laser or IPLS treatment.     

Vascular lasers and IPLS: guidelines for care from the European Society for Laser Dermatology (ESLD).

Dermatology and dermatologic surgery have rapidly evolved during the last two decades thanks to the numerous technological and scientific acquisitions focused on improved precision in the diagnosis and treatment of skin alterations. Given the proliferation of new devices for the treatment of vascular lesions, we have considerably changed our treatment approach. Lasers and non-coherent intense pulse light sources (IPLS) are based on the principle of selective photothermolysis and can be used for the treatment of many vascular skin lesions. A variety of lasers has recently been developed for the treatment of congenital and acquired vascular lesions which incorporate these concepts into their design. The list is a long one and includes pulsed dye (FPDL, APDL) lasers (577 nm, 585 nm and 595 nm), KTP lasers (532 nm), long pulsed alexandrite lasers (755 nm), pulsed diode lasers (in the range of 800 to 900 nm), long pulsed 1064 Nd:YAG lasers and intense pulsed light sources (IPLS, also called flash-lights or pulsed light sources). Several vascular lasers (such as argon, tunable dye, copper vapour, krypton lasers) which were used in the past are no longer useful as they pose a higher risk of complications such as dyschromia (hypopigmentation or hyperpigmentation) and scarring. By properly selecting the wavelength which is maximally absorbed by the target--also called the chromophore (haemoglobin in the red blood cells within the vessels)--and a corresponding pulse duration which is shorter than the thermal relaxation time of that target, the target can be preferentially injured without transferring significant amounts of energy to surrounding tissues (epidermis and surrounding dermal tissue). Larger structures require more time for sufficient heat absorption. Therefore, a longer laser-pulse duration has to be used. In addition, more deeply situated vessels require the use of longer laser wavelengths (in the infrared range) which can penetrate deeper into the skin. Although laser and light sources are very popular due to their non-invading nature, caution should be considered by practitioners and patients to avoid permanent side effects. These guidelines focus on patient selection and treatment protocol in order to provide safe and effective treatment. Physicians should always make the indication for the treatment and are responsible for setting the machine for each individual patient and each individual treatment. The type of laser or IPLS and their specific parameters must be adapted to the indication (such as the vessel's characteristics, e.g. diameter, colour and depth, the Fitzpatrick skin type). Treatments should start on a test patch and a treatment grid can improve accuracy. Cooling as well as a reduction of the fluence will prevent adverse effects such as pigment alteration and scar formation. A different number of repeated treatments should be done to achieve complete results of different vascular conditions. Sunscreen use before and after treatment will produce and maintain untanned skin. Individuals with dark skin, and especially tanned patients, are at higher risk for pigmentary changes and scars after the laser or IPLS treatment.     

Effects of cryogen spray cooling and high radiant exposures on selective vascular injury during laser irradiation of human skin

BACKGROUND: Increasing radiant exposure offers a means to increase treatment efficacy during laser-mediated treatment of vascular lesions, such as port-wine stains; however, excessive radiant exposure decreases selective vascular injury due to increased heat generation within the epidermis and collateral damage to perivascular collagen. OBJECTIVE: To determine if cryogen spray cooling could be used to maintain selective vascular injury (ie, prevent epidermal and perivascular collagen damage) when using high radiant exposures (16-30 J/cm2). DESIGN: Observational study. SETTING: Academic hospital and research laboratory. PATIENTS: Twenty women with normal abdominal skin (skin phototypes I-VI). INTERVENTIONS: Skin was irradiated with a pulsed dye laser (wavelength = 585 nm; pulse duration = 1.5 milliseconds; 5-mm-diameter spot) using various radiant exposures (8-30 J/cm2) without and with cryogen spray cooling (50- to 300-millisecond cryogen spurts). MAIN OUTCOME MEASURE: Hematoxylin-eosin-stained histologic sections from each irradiated site were examined for the degree of epidermal damage, maximum depth of red blood cell coagulation, and percentage of vessels containing perivascular collagen coagulation. RESULTS: Long cryogen spurt durations (>200 milliseconds) protected the epidermis in light-skinned individuals (skin phototypes I-IV) at the highest radiant exposure (30 J/cm2); however, epidermal protection could not be achieved in dark-skinned individuals (skin phototypes V-VI) even at the lowest radiant exposure (8 J/cm2). The red blood cell coagulation depth increased with increasing radiant exposure (to >2.5 mm for skin phototypes I-IV and to approximately 1.2 mm for skin phototypes V-VI). In addition, long cryogen spurt durations (>200 milliseconds) prevented perivascular collagen coagulation in all skin types. CONCLUSIONS: Cryogen spurt durations much longer than those currently used in therapy (>200 milliseconds) may be clinically useful for protecting the epidermis and perivascular tissues when using high radiant exposures during cutaneous laser therapies. Additional studies are necessary to prove clinical safety of these protocols.     

Action spectrum of vascular specific injury using pulsed irradiation

It has been clearly demonstrated that cutaneous blood vessels will be selectively damaged by a laser whose wavelength matches one of the three absorption spectral peaks of the chromophore, oxyhemoglobin, for example, 577 nm. A restriction in the application of this wavelength for the treatment of benign cutaneous vascular tumors, such as portwine stains, has been the penetration depth of 577 nm irradiation of approximately 0.5 mm from the dermal epidermal junction (DEJ). This study was undertaken to establish whether it was possible to increase the penetration depth from 0.5 mm by changing the wavelength to beyond 577 nm in albino pig skin. Results from this study confirm that penetration depth increases from 0.5 to 1.2 mm by changing the wavelength from 577 to 585 nm at 4 J/cm2, while maintaining the same degree of vascular selectivity as that previously described after 577 nm irradiation. This occurred in spite of a mismatch in the wavelength between 585 nm and the oxyhemoglobin absorption peak of 577 nm. Unlike 585 nm irradiation and in contrast with theoretical predictions, 590 nm laser light did not penetrate as deeply as 585 nm. Not only was there a reduction in the penetration depth of the laser beam from 1.2 mm at 585 nm to 0.8 mm at 590 nm, at 4 J/cm2, but there was also a decrease in vascular selectivity in albino pig skin exposed to 590 nm irradiation.     

Ablative laser resurfacing: high-energy pulsed carbon dioxide and erbium:yttrium-aluminum-garnet

The development of the short-pulsed high-energy carbon dioxide laser in the mid 1990's led to the emergence of laser skin resurfacing. Used in the continuous mode, the CO(2) laser can cut and coagulate simultaneously. Used in the pulsed mode, the CO(2) laser is a powerful tool for epidermal ablation in many different contexts both therapeutic and cosmetic. Both the CO(2) and Erbium YAG lasers emit light in the infrared spectrum. Energy is preferentially absorbed by intracellular water creating rapid heating and vaporization of tissue. Because of the wavelength of the Er:YAG laser (2940 nm) more closely approximates the absorption peak of water (3000 nm) the target chromophore than the CO(2) laser (10,600 nm) nearly all of the energy is absorbed in the epidermis and papillary dermis yielding superficial ablation and less underlying thermal damage. The advantages, disadvantages, and applications of each type of laser resurfacing will be discussed. Despite proven efficacy, the public acceptance of laser resurfacing has declined with the emergence of new laser systems that cause dermal remodeling without ablating the overlying epidermis dramatically reducing recovery time. In the absence of blinded comparison studies, it remains unclear whether the clinical results of the newer 'nonablative' laser systems compare with their ablative predecessors.     

Histologic comparison of argon and tunable dye lasers in the treatment of tattoos

Cosmetic benefit from laser therapy of tattoos may simply be the result of thermal injury and host reparative response which remove pigment by a "slough and bury" mechanism. Tattoo pigment of 4 colors (black, white, red, and blue) was introduced into the skin of guinea pigs and studied histologically at 48 h, 7 days, 4 and 6 weeks, and 3 months. Tattoos of each color were treated with argon laser (488 and 514 nm) and tunable dye laser at 3 different wavelengths (505, 577, and 690 nm). Treated tattoos were biopsied immediately and at 48 h, 7 days, and 3 months. Selective laser absorption by the tattoo pigment was suggested by pigment-related differences in threshold doses for histologic damage. Clinical clearing of tattoo pigment correlated well with the extent of immediate epidermal and dermal necrosis and was as well associated histologically with the deposition of parallel bands of collagen fibers (i.e., scar) between the residual pigment and the overlying epidermis. "Lightening" of tattoos probably depends more on widespread necrosis, subsequent tissue sloughing, and resultant dermal fibrosis than on specific changes in tattoo pigment chemistry, morphology, physical properties, or handling by macrophages.     

Comparative histochemistry of port-wine stains after copper vapor laser (578 nm) and argon laser treatment.

The present study compared the histologic changes occurring 15 min after copper vapor laser (CVL; operating at 578 nm) and argon laser (488/514 nm) treatment of port-wine stains (PWS) over a range of energy densities (8-32 J/cm2) with corresponding pulse widths of 50-200 ms. Frozen tissue sections were stained with nitroblue tetrazolium chloride (NBTC). This histochemical method permits an accurate color differentiation between blue-stained viable and unstained thermally damaged cells. At 8, 10, and 12 J/cm2 the argon-laser injury was confined to epidermal cell layers; none to superficial dermal effects were found. Fluences of at least 15 J/cm2 produced a diffuse NBTC-negative coagulation necrosis. Exposure of PWS skin to 8-12 J/cm2 at 578 nm did not alter the integrity of epidermal cells. In the dermis, damage was confined to blood vessels and surrounding collagen, showing a clear demarcation from adjacent viable structures. The maximum penetration depth achieved with these vessel selective energy densities was 0.44 mm. At 15 J/cm2, besides vascular injury, damage to the basal cell layer also occurred. At fluences of 17-20 J/cm2 a diffuse necrosis similar to that induced by the argon laser was found. Vessel selectivity of the 578 nm wave band was achieved with pulse widths from 50-74 ms, exceeding the estimated "ideal" exposure time (0.1-10.0 ms) for a vascular selective laser effect. The NBTC method allowed identification of subtle laser-induced tissue changes providing accurate quantitative data relating to the extent of vascular injury.     

Wavelength and fluence effect on vascular damage with photodynamic therapy on skin

Normal skin phototoxicity is clinically predictable during photodynamic therapy with light at 690 and 458 nm wavelengths, in the first 5 h after intravenous bolus infusion of benzoporphyrin derivative mono-acid ring A. This study goal was to determine histologic milestones that lead to tissue necrosis with exposure to red (690 nm) and blue (458 nm) light. The threshold doses for skin necrosis on rabbits were equal at both wavelengths. Lower, equal to, and higher than threshold fluences were delivered in duplicates at hourly intervals, with 40% increments, at constant irradiance. Pathology specimens from irradiated and control sites, were collected at 0, 2, 7, 24, 48 h, and 2 wk after treatment and were paired to equivalent treated sites for clinical evaluation. Immediately after irradiation, at 690 and 458 nm thresholds, light microscopy showed stasis and inflammatory infiltrate in the papillary dermis, respectively; electron microscopy demonstrated pericyte and endothelial cell damage - greater at 690 than 458 nm. At day 1, vascular stasis in the dermis showed a steeper dose-response with red than blue light, and led to necrosis of skin appendages (day 1) and epidermis (days 1-2) at both wavelengths. Sub-threshold fluences induced similar, but significantly milder (p < 0.05) changes and epidermis recovered. Skin necrosis, at threshold fluences in photodynamic therapy with benzoporphyrin derivative mono-acid ring A, was primarily due to vascular compromise to a depth potentially reaching the subcutaneous muscle at 690 nm, whereas at 458 nm vascular damage was confined to upper dermis. This system facilitates selective destruction of skin vasculature, sparing normal epidermis.     

Increased dermal expression of platelet-derived growth factor receptors in growth-activated skin wounds and psoriasis.

Platelet-derived growth factor (PDGF) is a potent mitogenic and chemotactic factor for fibroblasts and other cell types. PDGF effects are mediated by binding of PDGF to dimeric PDGF receptors possessing intrinsic tyrosine kinase activity. We examined the expression pattern of PDGF receptors in cryostat sections of normal and growth-activated human skin using a monoclonal antibody, PR7212, specific for the beta subunit of the PDGF receptor. PDGF receptors were expressed at low levels in normal skin, with only occasional staining of dermal connective tissue cells. In contrast, PDGF receptor expression was greatly elevated in the dermis of growth-activated skin from 15 chronic wounds and 10 psoriatic lesions. PDGF receptors were increased in dermal fibroblasts and in dermal blood vessels in both conditions. Immunoblot analysis confirmed the increased expression of beta-subtype PDGF receptors in psoriatic lesional tissue. PDGF receptors were not detected in normal or growth-activated epidermis. Differential expression of PDGF receptors could regulate increased proliferation of vascular and connective tissue cells observed in psoriasis and chronic wounds.     

Occupational argyria; light and electron microscopic studies and X-ray microanalysis

Microscopic studies have been performed on skin biopsies from five patients with occupational argyria. Small brown-black granules were present in the dermis on light microscopy and were intensely refractile with dark-field illumination. Electron microscopy showed that the granules were electron-dense, round or oval in shape and varied in size from 30 nm to 100 nm. They were most numerous in relation to the basal lamina of the eccrine sweat glands, but were also present in relation to the basal lamina of the epidermis and dermal elastic fibres. X-ray microanalysis confirmed that many of the granules contained silver and sulphur. However, selenium, mercury, titanium and iron were also identified and it is probable that these elements were deposited in the skin also as a result of occupational exposure.     

A case of pemphigus vulgaris with predilection for exposed areas

A 35-year-old man with the bullous lesions on the face and forearms was reported. Histopathological studies revealed the presence of acantholysis. Direct immunofluorescent (DIF) investigation showed depositions of IgG and C3 in the intercellular space of the epidermis. While the patient was successfully treated with oral prednisolone, we tried to induce the lesion by applying middle wave ultraviolet (UVB) on the uninvolved skin of the back. After irradiation of 5 MED of UVB, deposition of IgG in the intercellular space of the epidermis corresponding to the irradiated region was revealed by DIF, but no acantholysis was observed. When the serum which had been taken before the corticosteroid administration was injected on the uninvolved skin of the back followed the irradiation of the same dose of UVB, upper dermal infiltration of neutrophils was observed in addition to the above findings. The results indicate that the possible relation between UVB and production of the lesions was not obtained, however, in view of the clinical distribution of the lesions and IgG deposits by the irradiation of UVB, we should consider the relation between pemphigus vulgaris and the light.     

Erythropoietic protoporphyria—submicroscopic events during the acute photosensitivity flare

The immediate response of erythropoietic protoporphyria (EPP) skin to long-wave ultraviolet radiation (UVR) was studied with the electron microscope. The main finding was severe vascular injury. This was confined to the superficial vessels of the dermis and consisted of endothelial cell degeneration and a pronounced leakage of vascular contents. In contrast, the epidermis showed no abnormalities. Short-wave UV irradiation of EPP skin resulted in epidermal changes typical for the usual sunburn reaction and spared the dermal blood vessels. The following conclusions are drawn: (i) Endothelial cells are the primary cellular target for the photodynamic reaction in EPP. (ii) The fibrillar material, characteristic for chronic EPP lesions, originates from the vessels and vascular contents. (iii) The multilayered basement membranes observed in such lesions reflect multiple consecutive reparative processes that follow endothelial injuries.     

Fine structural deformation of the dermal capillary following immersion fixation procedure

The possibility of fine structural deformation related to skin biopsy and the subsequent immersion fixation procedure were investigated, because little attention has yet been focused on artifacts of the dermal microvasculature. Contraction of the material following biopsy removal was marked in skin regions with thin epidermis and resulted in capillary collapse. As the collapse of the vessels increased, lining cells became thicker and more rugged, endothelial fenestrations disappeared, and 10 nm filaments aggregated. Simultaneously, perivascular connective tissue material was separated from the dermal element in which the vessels were embedded and appeared as a homogenous areola around the endothelial tube. Basal lamina appeared folded and partially multilaminated around the vascular circumference, particularly in the venous segment of the microvasculature; these are considered to be the definite characteristics of dermal capillaries. In contrast to the skin regions with thin epidermis, the vessels in “well developed” dermal papillae did not collapse and bore close similarities to the perfused ones. The present study indicates that most of the so-called characteristics of dermal capillaries in biopsy skin is attributable to artifacts following the removal of the skin before fixation.     

Basics of laser application to dermatology

Q-switched lasers, with a pulse of light sufficiently short (nanosecond-domain) is demonstrated to be useful for treatment of dermal melanocytosis, blue-black tattoos, melanocytic nevi, and solar lentigines, although transient postinflammatory hyperpigmentation usually developed in the irradiated area during the following 3-4 months. If the postinflammatory pigmentation does not disappear after 1 year, incontinentia pigmenti histologica is a possibility. However, the pigment in café-au-lait macules responds variably to treatment. Melasma shows no response to laser. Therefore, accurate diagnosis is the key to success in the laser treatment. Laser treatment of vascular lesions is based on selective absorption by blood with thermal injury to the vessel wall. Therefore, the pulse-width of the vascular-specific lasers must be longer (microsecond-domain) than that of pigment-specific lasers. Because the wavelength of the lasers for vascular lesions, however, cannot penetrate into the deep areas of the skin, not all vascular lesions can be treated. Laser or light-assisted hair removal offers an efficient way to permanently reduce excessive hair growth. Skin rejuvenation is possible by laser or pulsed light with millisecond-domain pulse-width. Because these light sources, however, cause severe damage to the skin surface, the exposure energy must be reduced and the treatment must be combined with cooling devices. Therefore, the clinical results of light-assisted skin rejuvenation are not prominent. In conclusion, the pulse-width and wavelength of the laser light are critical parameters for laser treatments. If we obtain information about these parameters for specific lasers, we can expect the results of the treatment to be positive.     

Basics of laser application to dermatology

Q-switched lasers, with a pulse of light sufficiently short (nanosecond-domain) is demonstrated to be useful for treatment of dermal melanocytosis, blue–black tattoos, melanocytic nevi, and solar lentigines, although transient postinflammatory hyperpigmentation usually developed in the irradiated area during the following 3–4 months. If the postinflammatory pigmentation does not disappear after 1 year, incontinentia pigmenti histologica is a possibility. However, the pigment in café-au-lait macules responds variably to treatment. Melasma shows no response to laser. Therefore, accurate diagnosis is the key to success in the laser treatment. Laser treatment of vascular lesions is based on selective absorption by blood with thermal injury to the vessel wall. Therefore, the pulse-width of the vascular-specific lasers must be longer (microsecond-domain) than that of pigment-specific lasers. Because the wavelength of the lasers for vascular lesions, however, cannot penetrate into the deep areas of the skin, not all vascular lesions can be treated. Laser or light-assisted hair removal offers an efficient way to permanently reduce excessive hair growth. Skin rejuvenation is possible by laser or pulsed light with millisecond-domain pulse-width. Because these light sources, however, cause severe damage to the skin surface, the exposure energy must be reduced and the treatment must be combined with cooling devices. Therefore, the clinical results of light-assisted skin rejuvenation are not prominent. In conclusion, the pulse-width and wavelength of the laser light are critical parameters for laser treatments. If we obtain information about these parameters for specific lasers, we can expect the results of the treatment to be positive.     

Toll样受体2和4在银屑病皮损中的表达

目的研究Toll样受体（TLR）2和4在银屑病皮损中的表达，探讨其与银屑病发病的关系。方法选用16例滴状银屑病、13例斑块状银屑病患者及10例正常人皮肤的石蜡切片．用免疫组化的方法研究TLR2和TLR4的表达。结果10例正常人皮肤的基底层均有较弱的TLR2表达而无TLR4表达．真皮血管内皮细胞未见TLR2及TLR4表达。所有16例滴状银屑病、13例斑块状银屑病皮损的基底细胞层均可见明显的TLR2表达，棘层也有弱表达；TLR4则呈现表皮全层的弥漫性强表达。银屑病真皮浅层血管内皮细胞可见明显的TLR2及TLR4表达。结论TLR2、TLR4在银屑病皮损均有表达，TLR4的表达更高：提示感染相关免疫与银屑病发病关系密切。     

Altered binding of Ulex europaeus I lectin to psoriatic epidermis

We have used Ulex europaeus I (UEA I) lectin, specific for α-l -fucose-containing glycoconjugates, in fluorescence microscopy to stain cryostat sections of human skin from normal persons and patients with psoriasis and lichen simplex. In normal skin the upper layers of the stratum spinosum and the stratum granulosum were strongly reactive with UEA I, whereas the lower layers of the epidermis did not react. The staining intensity of the upper epidermis was similar to that of the endothelium of dermal blood vessels. Biopsies of the lesional skin of lichen simplex showed an intense UEA I-specific staining throughout the whole epidermis, similar in intensity to that seen in the upper epidermis of normal skin. In psoriatic lesions positive UEA I-specific fluorescence was seen throughout the whole epidermis, but the fluorescence was more faint and often granular. In uninvolved skin of psoriatic patients the whole epidermis showed a diffuse UEA I-specific fluorescence, differing in this respect from normal skin. In normal skin UEA I binds to epidermal cells which are at a certain state of differentiation. The results with psoriatic epidermis confirm that both uninvolved and lesional epidermis have a defect in epidermal maturation, as shown by the altered binding of UEA I lectin.     

Scanning electromicroscopy of suction blister-roofs from psoriatic lesions and normal skin

Suction blisters were raised on psoriatic lesions and normal appearing skin. The epidermis was separated at the epidermal-dermal junction. Scanning electronmicroscopy of the dermal side of the blister-roofs from normal looking skin and almost healed psoriatic lesions showed stellate cells probably formed by cytoplasmic extensions ending at desmosomes. In non-treated psoriatic plaques the cells were rounded and lacked the stellate extensions.