Phototherapy, photodynamic therapy and photophoresis in the treatment of connective-tissue diseases: a review.

Connective-tissue disorders, which include lupus erythematosus, morphoea/scleroderma and dermatomyositis, are characterized by cutaneous manifestations that are sometimes resistant to conventional therapy. Light treatments, which include phototherapy, photodynamic therapy (PDT) and photopheresis, are routinely utilized in the treatment of dermatological conditions and may provide unique mechanisms of action in the treatment of these connective-tissue disorders. The objective of this study is to conduct a review of the literature that describes the use of phototherapy, PDT and photopheresis in the treatment of lupus erythematosus, morphoea/scleroderma and dermatomyositis. A MEDLINE search was conducted to find articles that discuss treatment of connective-tissue diseases with light therapies and more than 30 publications that discuss light therapy for these diseases were identified. These range in design from case reports to randomized, prospective trials. Study outcomes and details were summarized and presented within each connective-tissue disease by light therapy modality, which includes phototherapy, PDT and photopheresis. Although there is a known association between photosensitivity and connective-tissue diseases, light therapies, when used appropriately, may be legitimate therapeutic options for recalcitrant cutaneous manifestations in lupus erythematosus, morphoea/scleroderma and dermatomyositis.

Methotrexate in the treatment of pemphigus vulgaris: experience in 23 patients.

BACKGROUND: The standard treatment for patients with pemphigus vulgaris has long consisted of high-dose glucocorticoids. Studies regarding the use of methotrexate in pemphigus vulgaris date back to 1968, but few have quantitatively described a steroid-sparing effect conferred by methotrexate. OBJECTIVES: We sought to evaluate the efficacy of methotrexate in 23 patients with pemphigus vulgaris, using the drug's steroid-sparing effect as the primary indicator of clinical improvement. We investigated whether methotrexate could be used as monotherapy in some patients. METHODS: Retrospective chart review was used to analyse the records of patients with pemphigus vulgaris treated with methotrexate at the New York University Langone Medical Center for at least three consecutive months between 2000 and 2012. Diagnosis was made by tissue biopsy and either direct or indirect immunofluorescence tests and enzyme-linked immunosorbent assay. RESULTS: Improvement in clinical symptoms was observed in 91% of patients. Sixteen patients (70%) were eventually weaned completely off prednisone, with a mean time to discontinuation of 18 months. In total 23% of patients enjoyed a partial steroid-sparing effect, requiring a mean maintenance dose of prednisone of 6·75 mg daily. Two patients (9%) developed possible adverse events requiring cessation of the drug, and one patient received no therapeutic benefit from the drug. CONCLUSIONS: Methotrexate is a useful and well-tolerated therapy with considerable steroid-sparing effect in patients with pemphigus vulgaris. It may be considered a first-line adjuvant therapy in the treatment of this difficult disease.

Functional characterization of synthetic leukotriene B and its stereochemical isomers.

Leukotriene B (LTB), a potent lipid chemotactic factor for neutrophils, is 5S,12R-dihydroxy-6,14-cis,8,10-trans-eicosatetraenoic acid (Fig 1), based upon direct comparison of natural LTB with synthetic 5S,12R-dihydroxy-6,8,10,14-eicosatetraenoic acid (5,12-di-HETE) stereoisomers in three biological assays. Of the six synthetic stereoisomers evaluated, only the 5S,12R,6,14-cis,8,10-trans compound had chemotactic potency for human neutrophils in vitro that was comparable to that of natural LTB, with a concentration of 3 X 10(9-9) M eliciting a one-half maximum response. In contrast, the racemic mixture of 5R,12R- and 5S,12S-6,10-trans,8,14-cis, the racemic mixture of 5S,12R- and 5R,12S-6,10-trans,8,14-cis, the 5S,12R-6,8-trans,10,14-cis, the 5S,12R-6,8,10-trans,14-cis, and the 5S,12S-6,8,10-trans,14-cis stereoisomers required concentrations of 3 X 10(-7) to 1 X 10(-6) M to elicit comparable responses. Only natural LTB and its synthetic counterpart elicited a local neutrophil infiltration when injected into the skin of the rhesus monkey at 10 ng and 100 ng per site. Natural and synthetic LTB at a concentration of 3 X 10(-8) M each provoked an EC25 contractile response of guinea pig pulmonary parenchymal strips in vitro, whereas the other four tested stereoisomers of 5,12-di-HETE were inactive at this concentration. Structure-function analyses suggest that the neutrophil chemotactic activity depends critically upon the C-1 to C-12 domain, including the stereochemistry of the 6-,8-,and 10-olefinic bonds and the presence of both hydroxyl groups.

Erythropoietic protoporphyria. Photoactivation of the complement system.

The complement system was analysed in 14 asymptomatic patients with erythropoietic protoporphyria. In the majority of the sera studied the levels of complement components C1, C4, C2, and C3 were within the normal range. Upon ultraviolet light (330--460 nm) irradiation of the serum samples in vitro, a marked decrease in total hemolytic activity accompanied by reduction of C1, C4, C2, and C3 levels was observed. The loss of total hemolytic activity can be directly correlated with the levels of protoporphyrin (PP) and similar changes can be obtained in normal serum upon addition of PP followedf by ultraviolet light irradiation. It is postulated that after irradiation the excited PP develops the capacity to activate the complement sequence with the production of cleavage products, which may contribute to the skin changes observed in these patients upon sun exposure.

Cold urticaria. Recognition and characterization of a neutrophil chemotactic factor which appears in serum during experimental cold challenge.

Sera were obtained from the venous effluents of cold-challenged arms of patients with idiopathic cold urticaria without plasma or serum cryoproteins; these sera exhibited increased neutrophil chemotactic activity without alterations of the complement system. A two- to fourfold augmentation of the base-line neutrophil chemotactic activity of serum from the immersed extremity began within 1 min, peaked at 2 min, and returned to base-line levels within 15 min, whereas there was no change in the serum chemotactic activity in the control arm. The augmented chemotactic activity in the serum specimens from the challenged arm of each patient appeared in a high molecular-weight region, as assessed by the difference in activity recovered after Sephadex G-200 gel filtration of the paired lesional and control specimens. Sequential purification of this high molecular-weight activity by anion- and cation-exchange chromatography revealed a single peak of activity at both steps. The partially purified material continued to exhibit a high molecular weight, being excluded on Sepharose 4B, and had a neutral isoelectric point. The partially purified material showed a preferential chemotactic activity for neutrophilic polymorphonuclear leukocytes, required a gradient for expression of this function, and exhibited a capacity to deactivate this cell type. This active principle, termed high molecular-weight neutrophil chemotactic factor, exhibited a time-course of release that could be superimposed upon that of histamine and the low molecular-weight eosinophil chemotactic factor and may represent another mast cell-derived mediator.

Cutaneous late-phase response to allergen. Mediator release and inflammatory cell infiltration.

To better define the inflammatory infiltrates and kinetics of mediator release during the cutaneous late-phase reaction (LPR), we examined skin biopsies at 8 h, and skin chamber cell counts and mediator release for 12 h after antigen challenge. Compared with the control sites, the antigen-stimulated biopsy sites contained 14 times as many basophils (P less than 0.01) and six times as many eosinophils (P less than 0.001) with one to two fold more mononuclear cells (P less than 0.03) and neutrophils (P less than or equal to 0.01). Similar changes were found in the skin chambers. Although there were neutrophils in the control chamber, they were only twice as numerous in the antigen challenged site (P less than 0.01). Eosinophils were 35-fold (P less than or equal to 0.03) more prevalent in the antigen chamber than the control chamber for hours 8-12 and basophils were noted starting in the eighth hour and were 20-fold (P less than or equal to 0.03) more concentrated in the antigen chamber during the next 4 h. The mononuclear cells were not significantly different between antigen and control blisters. With respect to inflammatory mediators, there was an initial peak of histamine (13.2 +/- 2.9 ng/ml) in the blister fluid at 1 h. The level then fell to approximately 2 ng/ml, followed by a secondary rise starting at the eighth hour and increasing to 9.8 +/- 2.8 ng/ml by the twelfth hour. This secondary increase in histamine correlated significantly (r = 0.81, P less than 0.05) with the observed influx of basophils. PGD2 in the blister fluid rose to 371+/-25 pg/ml during the first 4 h and then slowly decreased to half this level during the last 4 h. Thus, the cutaneous LPR has been shown to manifest a secondary increase in histamine levels and a markedly specific increase in eosinophils and basophils with mediator release apparently being derived from the latter cells.

Evaluation of role played by mediators of immediate hypersensitivity in exercise-induced asthma.

To determine whether mediators of immediate hypersensitivity played a role in the pathogenesis of exercise-induced asthma, we measured the concentration of histamine and neutrophil-chemotactic activity present in systemic arterial blood during thermal challenges in five asymptomatic asthmatics. Because exercise-induced asthma has been shown to be a result of respiratory heat loss and because respiratory heat loss during isocapnic hyperventilation has been shown to give identical responses, we chose the latter provocational method in order to minimize increases in cardiac output that might interfere with the interpretation of mediator concentrations in arterial blood. Multiple aspects of pulmonary mechanics were also recorded before and after provocation. The results of these studies were then compared with the effects observed when the same subjects inhaled aerosols of specific antigens on the same day. Each challenge produced identical alterations in lung function, and neither was associated with consistent changes in arterial histamine. However, antigen provocation evoked a sustained and prolonged release of neutrophil chemotactic activity in each subject, whereas isocapnic hyperventilation with cold air was without effect. These data strongly suggest that mast-cell derived mediators are not involved in the development or maintenance of the bronchial obstruction that follows exercise in asthmatics.

Mast cells in cutaneous inflammatory disorders.

Mast cells in skin are distributed around dermal and subcutaneous blood vessels. Activation of tissue mast cells produces secretion and/or generation and secretion of a variety of biologically active molecules. Mast-cell-dependent mediators may be classified as smooth-muscle-contracting and vasoactive activities, chemotactic factors, enzymes, and proteoglycans. These mediators alter the microenvironment to produce a biphasic response. The initial or humoral phase of the response is mediated by materials that alter vascular permeability; peripheral blood leukocytes attracted by chemotactic factors establish the cellular phase. Failure to limit the humoral phase creates a pharmacologic state that may be recognized in skin as urticaria/angioedema. The inability to control the cellular phase permits progression to a local inflammatory state with subacute and chronic tissue injury recognized in skin, for example, as necrotizing vasculitis. As an example of the former, certain forms of physical urticaria have provided experimental models in humans to allow observation of the clinical manifestations, study of tissue alterations by histologic analysis, measurement of mediators released into the circulation, and assessment of motility of peripheral blood leukocytes. An example of the role of the mast cell in the production of subacute and chronic inflammatory cutaneous disease is suggested by studies in a patient in whom exposure to the physical stimuli of cold and trauma was followed by initial mast cell degranulation, subsequent tissue deposition of circulating immune complexes, and the development of a necrotizing vasculitis.

Mast cells in cutaneous inflammatory disorders.

Mast cells in skin are distributed around dermal and subcutaneous blood vessels. Activation of tissue mast cells produces secretion and/or generation and secretion of a variety of biologically active molecules. Mast-cell-dependent mediators may be classified as smooth-muscle-contracting and vasoactive activities, chemotactic factors, enzymes, and proteoglycans. These mediators alter the microenvironment to produce a biphasic response. The initial or humoral phase of the response is mediated by materials that alter vascular permeability; peripheral blood leukocytes attracted by chemotactic factors establish the cellular phase. Failure to limit the humoral phase creates a pharmacologic state that may be recognized in skin as urticaria/angioedema. The inability to control the cellular phase permits progression to a local inflammatory state with subacute and chronic tissue injury recognized in skin, for example, as necrotizing vasculitis. As an example of the former, certain forms of physical urticaria have provided experimental models in humans to allow observation of the clinical manifestations, study of tissue alterations by histologic analysis, measurement of mediators released into the circulation, and assessment of motility of peripheral blood leukocytes. An example of the role of the mast cell in the production of subacute and chronic inflammatory cutaneous disease is suggested by studies in a patient in whom exposure to the physical stimuli of cold and trauma was followed by initial mast cell degranulation, subsequent tissue deposition of circulating immune complexes, and the development of a necrotizing vasculitis.

High molecular weight neutrophil chemotactic factor: recognition, characterization, and role in the deactivation of neutrophillic leukocytes.

Idiopathic acquired cold-induced urticaria has provided a model to study release of mast cell-derived chemical mediators into the blood and alterations of neutrophilic leukocyte motility. A factor chemotactic for neutrophilic leukocytes appeared in the circulation after local experimental challenge with ice. After partial purification by Sephadex G-200 gel filtration and by anion and cation exchange chromatography the neutrophil chemotactic activity was excluded on Sepharose 4B gel filtration, indicating a molecular weight in excess of 750,000. On isoelectric focusing it exhibited a neutral isoelectric point. This chemotactic factor showed preferential chemotactic activity for neutrophils and deactivated these cells in vitro and in vivo. HMW-NCF may prove to be a useful marker of mast cell activation and its release may modulate the capacity for motility of neutrophilic leukocytes in humans.

Clinical presentations and mechanisms of necrotizing angitis of the skin.

Cutaneous necrotizing angiitis may be present as either palpable purpura or less commonly as recurrent urticaria, and each clinical presentation may be associated with hypocomplementemia or a normal complement system. A variety of mechanisms may be operative in the production of necrotic vascular skin lesions that appear as similar, recognizable morphologic lesions. These mechanisms include immune complexes, cellular-type hypersensitivity reactions, and initiation or modulation by mast cells. Two cellular patterns have been recognized in the skin of patients with cutaneous necrotizing angiitis that can be correlated with the involvement of the complement system in serum. In patients with hypocomplementemia, there is an infiltrate of neutrophils that is consistent with a process involving immune complexes; in patients with normocomplementemia there are lymphocytes and activated lymphocytes consistent with participation in part by cellular mechanisms. In both the hypocomplementemic and normocomplementemic forms and as well as in a unique patient in whom the mast cell may initiate the venular damage, the mast cell, which its content of chemical mediators, has the capacity to initiate as well as modulate subacute and chronic vascular damage.

The skin in mastocytosis.

The most frequent site of organ involvement in patients with any form of mastocytosis is the skin. Cutaneous expressions include urticaria pigmentosa, mastocytoma, diffuse and erythrodermic cutaneous mastocytosis, and telangiectasia macularis eruptiva perstans. The cutaneous lesions tend to appear early in life. Although urticaria pigmentosa has been reported in 12 pairs of twins and one set of triplets, the majority of affected individuals have no familial association. Most patients with systemic mastocytosis have skin lesions; however, an occasional patient will have systemic disease with no other skin features than flushing. In lesional cutaneous sites and in non-lesional skin, there is an increase in the number of mast cells. Electron microscopy shows quantitative differences between lesional skin mast cells from patients with and without systemic disease. The mast cells from adult patients with systemic disease have a larger mean cytoplasmic area, nuclear size, and granule diameter. The granules contain predominantly grating/lattice structures. The cutaneous mast cells contain tryptase and chymase. They retain their functional reactivities to relevant secretory stimuli, such as C3a, morphine sulfate, and calcium ionophore A23187. Lesional skin contains histamine, leukotriene B4, prostaglandin D2, 5-hydroxyeicosatetraenoic acid, platelet-activating factor, and heparin. Treatment of the cutaneous manifestations includes the use of H1 and H2 antihistamines, oral disodium cromoglycate, psoralens plus ultraviolet A photochemotherapy, and potent topical corticosteroid preparations.

The diversity of mast cell-derived mediators: implications for acute, subacute, and chronic cutaneous inflammatory disorders.

The mast cell in tissues represents an effector cell capable of elaboration of all the essential mediators of inflammation. The effects of uncontrolled activation may be divided into pharmacologic and inflammatory phases with attendant implications for the initiation of both acute and subacute pathologic processes. The elaboration of chemical mediators by the mast cell makes it possible to recruit blood cells and proteins essential to host defense by a controlled physiologic process that can proceed without significant local tissue damage. When uncontrolled, the same potentiality can be injurious, with the nature of the clinical problem depending upon the location of the cells, the intensity of activation, and the ratio of newly generated and preformed mediators released. The evidence that the mast cell can participate in each form of immunologic reaction--immediate, immune complex, and delayed- as a primary or secondary effector cell and the diversity of its products foretell an evolving recognition of its role in host defense and tissue injury. It is pertinent to develop further methods and criteria to define the nature and extent of mast cell participation in disease processes.

In vivo mediator release and degranulation of mast cells in hematoporphyrin derivative-induced phototoxicity in mice.

This study was designed to assess the role of the mast cell in the early phase of hematoporphyrin derivative (HPD)-induced phototoxicity. BALB/c mice were rendered phototoxic by i.p. injection of hematoporphyrin derivative, followed by exposure to 13.6 kJ/m2 of 400-410 nm radiation. The phototoxic response was quantified by measurement of ear thickness immediately before the irradiation, and at 0, 0.5, 1, 1.5, and 2 h after. At these time-points, determinations of serum histamine and plasma leukotriene C4 levels and histologic examination of the ears were undertaken. Mice injected i.p. with buffered saline and subsequently irradiated served as controls. In mice exposed to HPD and radiation, a maximal peak increased ear-thickness of 125.7 +/- 14.4% (mean +/- SEM) was noted at 2 h; this was associated with a net increased serum histamine of over 120% and histologic evidence of mast cell degranulation. In addition, moderate increases in plasma levels of leukotriene C4 were observed at 0 h and 1.5 h in the HPD- and irradiation-treated animals. These data provide direct evidence for the participation of mast cells in the early phase of HPD-induced phototoxicity.

Effect of chronologic aging and ultraviolet irradiation on Langerhans cells in human epidermis.

The effect of aging on epidermal Langerhans cells (LC) and on their response to a single ultraviolet (UV) exposure was studied in skin biopsy specimens of healthy adults, 4 aged 22-26 yr and 7 aged 62-86 yr. In unirradiated skin, old adults had fewer LC than young adults, 5.8 +/- 1.1 versus 10.0 +/- 0.8 (mean +/- SEM) per 3 mm wide cross-section (p = .015). Following irradiation with 3 times the minimal erythema dose, recognizable LC were absent in all but 2 subjects within 24 hr. However, LC number fell less rapidly in old adults and was almost unchanged at 4 hours (5.8 +/- 1.1 versus 5.0 +/- 1.2), while in young adults LC number decreased from 10.0 +/- 0.8 to 3.3 +/- 1.3 during the same period (p less than .05). Other changes noted in both young and old subjects following irradiation included cytoplasmic vacuolization, frequent apposition of LC to severely damaged keratinocytes, and the finding of LC in the basal layer of the epidermis rather than exclusively suprabasilarly as in control sections. These data demonstrate an age-associated loss of epidermal LC and slowing of LC response to UV irradiation. UV-induced LC changes appear qualitatively similar in young and old adults and include histological evidence of cellular damage, transient association of LC with damaged keratinocytes, and possible migration of LC from the irradiated epidermis within 24 hr.

Chronologic aging alters the response to ultraviolet-induced inflammation in human skin.

In order to determine the effect of age on the capacity of human skin to mount an inflammatory response, the sunburn reaction was studied quantitatively in 4 subjects aged 22-26 yr and 7 subjects aged 62-86 yr. Buttock skin of each subject was exposed to 3 time his minimal erythema dose, using the Hanovia mercury vapor lamp; 1 micrometer histologic sections and determinations of histamine and prostaglandin E2 (PGE2) from suction blister aspirates were used to monitor the reaction. Clinically, erythema and edema were less (p less than .05) in irradiated skin of the old subjects during the first 24 hr. Nonirradiated skin contained less histamine and PGE2 in old adults (p less than .05), approximately 50% of young adult levels. Histamine levels rose early in the reaction and returned to baseline by 24 hr; 4 hr peak values averaged 9.2 ng/ml in old vs. 18.3 ng/ml in young adults. PGE2 rose more slowly in blister aspirates from old adults (P less than .05), but reached comparable peaks, 6-9 pg/T.V., in both groups at 24 hr. Biopsies of control skin from old adult specimens contained fewer mast cells and venules (P less than .01). At 4 and 24 hr, old specimens revealed fewer sunburn cells and less striking alterations of perivenular mast cells and endothelial cells, but at 72 hr these changes were more prominent than in young adult specimens. The data suggest that with advancing age the sunburn reaction is quantitatively reduced and evolves more slowly following a standardize ultraviolet exposure.

Cimetidine-induced augmentation of allergic contact hypersensitivity reactions in mice.

BALB/c mice were treated with cimetidine (100 mg/kg) or saline, intraperitoneally, twice daily, from days 0-2 or days 7-9 after sensitization with 0.1%, 2,4,6-trinitro-1-chlorobenzene (TNCB) on day 0. On day 7, the mice were challenged with 1% TNCB to one ear. Ear swelling responses (as an index of sensitization), serum histamine levels, and biopsy specimens of challenged ears were evaluated in groups of cimetidine- or saline-treated mice at 0, 0.5, 1, 1.5, 2, 4, 6, 8, 12, 24, and 48 h after challenge. Additional controls included mice injected with saline or cimetidine and challenged with, but not sensitized to, TNCB (irritant controls). Treatment with cimetidine during the induction but not the elicitation of allergic contact hypersensitivity (ACH) produced a significant enhancement of the response throughout the first 48 h. There was no effect of cimetidine on antigen-presenting cells within the epidermis which might account for this enhancement. Similarly, no difference in mast cell morphology or serum histamine levels between cimetidine- and saline-treated groups was observed. Histologically, the cimetidine-treated animals showed a more intense cellular infiltrate, which was most noticeable at 24 to 48 h, at which time numerous subcorneal and perifollicular neutrophilic abscesses were observed. To further investigate the mechanism of action of cimetidine, mice were injected with cyclophosphamide (150 mg/kg) 2 d prior to sensitization. Mice treated with cyclophosphamide alone or in combination with cimetidine showed no additive or synergistic effect upon the ear swelling response. We conclude that enhancement of ACH by cimetidine is independent of any effect on mast cells or antigen-presenting cells, but may relate to a cimetidine-induced inhibition of the induction of T-suppressor cells at the time of sensitization.

Mast-cell heterogeneity: functional comparison of purified mouse cutaneous and peritoneal mast cells.

To investigate the functional heterogeneity of mouse mast cells, we extracted and purified cutaneous and peritoneal mast cells from 10- to 18-week-old BALB/c mice and compared their responses to secretagogues. Cutaneous mast cells (CMC) were extracted from mouse ears after digestion with hyaluronidase and collagenase in MEM containing 25% fetal calf serum and purified on a discontinuous Percoll gradient. The histamine content of cells obtained from the 30/40% interface was 1.0 +/- 0.1 pg/cell (mean +/- SE), with a mast-cell purity of 68.6 +/- 4.4% and a viability of greater than 93%. Peritoneal mast cells (PMC) were obtained by lavage with modified Tyrode's buffer followed by purification on 22.5% and 3-9% metrizamide gradients. The histamine content of cells was 12.2 +/- 0.8 pg/cell, with a mast-cell purity of 95.9 +/- 0.6% and a viability of greater than 95%. Histamine release induced by A23187 from CMC peaked at 3.0 microM A23187 (19.1 +/- 4.2%), at 3.0 min (22.3 +/- 2.3%), and at 30 degrees C (17.6 +/- 2.6%). In contrast, histamine release from PMC peaked at 8.0 microM of A23187 (49.4 +/- 12.1%) and at 15.0 min (48.5 +/- 12.2%). Release of histamine from PMC was observed at all the temperatures tested from 22 to 45 degrees C. Histamine release from CMC and PMC induced by A23187 was calcium dependent. Histamine release induced by compound 48/80 from CMC peaked at 0.5 micrograms/ml of compound 48/80 (23.0 +/- 7.4%) and at 5.0 min incubation (16.3 +/- 2.0%), whereas release from PMC peaked at 10.0 micrograms/ml (31.9 +/- 2.6%); release from PMC was similar at all the time points examined (1-15 min). Histamine release induced by substance P (SP) from both CMC and PMC peaked at 5.0 microM (18.8 +/- 6.6% and 12.6 +/- 3.7%, respectively); however, the maximal release from CMC occurred at 3.0 min (18.2 +/- 3.2%) and from PMC at 30.0 min (11.4 +/- 2.0%). SP-induced histamine release from CMC was calcium dependent, whereas release from PMC was only partially inhibited by EDTA. This study demonstrated that functional heterogeneity exists between these two populations of mast cells.

Mast cell participation during the elicitation of murine allergic contact hypersensitivity.

In order to evaluate mast cell participation in allergic contact hypersensitivity (ACH), BALB/c mice were sensitized with 0.1% trinitrochlorobenzene (TNCB). Immediately before challenge and at 1, 1.5, 2, 4, 6, 8, 12, 24, and 48 h after challenge with 1% TNCB, groups of animals had ear thickness measured, had blood collected for histamine determinations, and had both ears removed for histologic evaluation of mast cells. The increase in ear swelling was triphasic with peak increases at 1.5 h (14.3 +/- 1.6 X 10(-2) mm; mean +/- SEM), 8 h (19.9 +/- 1.8 X 10(-2) mm), and 24 h (30.2 +/- 2.9 X 10(-2) mm). A triphasic pattern of increased serum histamine was noted at 1-4 h (117% over control levels), at 12 h (131%), and at 48 h (133%). Examination of the tissue specimens from challenged animals showed modest (1+) degranulation of mast cells between 1 and 6 h with extensive (2+) degranulation at 12 h. In addition, hypogranulated mast cells were evident between 1 and 6 h, at 24 h, and at 48 h. There were no statistically significant differences in mast cell numbers at any time. Neither platelets nor other formed elements of the blood contributed to the increased blood histamine levels. These data show that mast cells are activated in a triphasic pattern during ACH, and thus suggest both early and late roles for the mast cell and its products in the evolution of ACH.

Cutaneous inflammation: effects of hydroxy acids and eicosanoid pathway inhibitors on vascular permeability.

Four metabolic products of arachidonic acid lipoxygenation, 5-hydroxyeicosatetraenoate (5-HETE), 12-HETE, 15-HETE, 5(S),12(S)-DiHETE, were injected intradermally into depilated dorsae of albino guinea pigs. The presence of intravenously injected 125I-bovine serum albumin (10uCi/kg) in 13-mm punch biopsy specimens served as a marker for altered vascular response; histologic changes were evaluated at 6 and 24 h after the injection in 1-micron-thick sections. Thirty minutes after the injections of 15 nanomoles and 60 nanomoles of 5-HETE, the ratios of radioactivity in HETE-injected to that in buffer-injected sites were 1.35 +/- 0.06 (mean +/- SE) and 2.80 +/- 0.27, respectively. Corresponding effects of 15-HETE were 1.39 +/- 0.17 and 1.63 +/- 0.21, respectively. Values for 60 nanomoles of 12-HETE and 5,12-DiHETE were intermediate in comparison with the above eicosanoids. The most notable histologic changes were a neutrophilic infiltrate induced by 12-HETE at 6 and 24 h, and neutrophilic and eosinophilic infiltrates in response to 5,12-DiHETE injection at 6 and 24 h. Effects of topically applied eicosanoid pathway inhibitors were also evaluated, using intradermally injected sodium arachidonate (AA) as agonist. Three mixed cyclooxygenase/lipoxygenase inhibitors, BW755C, phenidone, and nordihydroguaiaretic acid, suppressed vascular response by 9%, 9%, and 6% for 150 nmol of AA, and by 9%, 13%, and 12% for 300 nmol of AA, respectively. The cyclooxygenase inhibitor, indomethacin, induced suppressions of 39% for 150 nmol AA and 22% for 300 nmol AA, respectively. These data demonstrate that metabolites of both cyclooxygenase and lipoxygenase eicosanoid pathways are involved in alteration in vascular response accompanying cutaneous inflammation.