Characterization of intercellular adhesion molecule-1 and HLA-DR expression in normal and inflamed skin: modulation by recombinant gamma interferon and tumor necrosis factor

The CXCR3 activating chemokines IP-10, Mig, and IP-9 are expressed in allergic but not in irritant patch test reactions

Differentiation between allergic and irritant contact dermatitis reactions is difficult, as both inflammatory diseases are clinically, histologically, and immunohistologically very similar. Previous studies in mice revealed that the chemokine IP-10 is exclusively expressed in allergic contact dermatitis reactions. In the present study, we investigated whether the mRNA expression of IP-10 and the related CXCR3 activating chemokines, Mig and IP-9 are also differentially expressed in human allergic contact dermatitis and irritant contact dermatitis reactions. Skin biopsies from allergic (13 cases) and sodium lauryl sulfate-induced irritant patch test reactions (13 cases), obtained 1-72 h after patch testing, were studied by means of an in situ hybridization technique. Results of chemokine mRNA expression were correlated with clinical scoring, histology, and immunohistochemical data including the proportion of inflammatory cells expressing CXCR3, the receptor for IP-10, Mig, and IP-9, and ICAM-1 and HLA-DR expression on keratinocytes. IP-10, Mig, and IP-9 mRNA were detected in seven of nine allergic contact dermatitis reactions after 24-72 h, but not in sodium lauryl sulfate-induced irritant contact dermatitis reactions. ICAM-1 expression by keratinocytes was only found in allergic contact dermatitis reactions and correlated with chemokine expression. Moreover, up to 50% of the infiltrating cells in allergic contact dermatitis expressed CXCR3, in contrast to only 20% in irritant contact dermatitis reactions. In conclusion, we have demonstrated differences in chemokine expression between allergic contact dermatitis and irritant contact dermatitis reactions, which might reflect different regulatory mechanisms operating in these diseases and may be an important clue for differentiation between allergic contact dermatitis and irritant contact dermatitis reactions.

Recent developments in the understanding of the pathogenesis of psoriasis

Recent studies have provided new insights into the molecular mechanisms involved in the pathogenesis of psoriasis. Patients may inherit a predisposition to psoriasis, although the disease is expressed only after being triggered by certain environmental or antigenic factors. There is considerable genetic heterogeneity in psoriasis and several genetic loci associated with the occurrence of the disease have been identified. Although the underlying abnormality in psoriasis has not been definitively identified, recent evidence suggests that activated T lymphocytes play an important role in the pathogenesis of the disease. The activation of T lymphocytes can be mediated through antigen-presenting cells or through autoimmunity, and is influenced by cytokines. Recently developed animal models and in vitro studies of psoriasis have provided new evidence for the role of pathogenic lymphocytes in the initiation of the disease process. Further research will help to identify the susceptibility genes involved in psoriasis and provide a more complete understanding of the immunological basis of the disease. This should lead to the development of targeted therapies with improved efficacy and tolerability compared with some currently available treatments.

Mast cells in psoriatic skin are strongly positive for interferon-gamma

The increased number and early activation of cutaneous mast cells is a typical feature of psoriatic inflammation. Interferon-gamma (IFN-gamma) is believed to be one of the important mediators in the cytokine cascade of psoriasis. Human mast cells have been previously reported to release various cytokines upon stimulation including interleukin (IL) -4, IL-5, IL-6, IL-8, IL-13 and tumour necrosis factor-alpha. Here we report that human mast cells synthesize also IFN-gamma at mRNA and protein level and that the number of IFN-gamma producing mast cells is significantly increased in the psoriatic skin. IFN-gamma immunoreactivity in mast cells was demonstrated by staining non-lesional and lesional skin sections from 21 patients with psoriasis. Ten patients with atopic dermatitis (AD) and five healthy persons served as control groups. The percentage (mean +/- SD) of IFN-gamma + mast cells in lesional compared with non-lesional psoriatic skin was 67 +/- 18% vs. 44 +/- 17% (P < 0.0001, paired t-test), respectively, but only 9 +/- 6% vs. 10 +/- 7% in corresponding skin samples of AD. In the skin of healthy controls, only 12 +/- 12% of the mast cells were IFN-gamma +. Using immunoelectron microscopy, we confirmed the ultrastructural localization of IFN-gamma within the granules of mast cells in psoriatic skin. In addition, stimulation of a human mast cell line HMC-1 with phorbol myristate acetate (PMA) (100 nmol/L) for periods of 2-24 h induced expression of IFN-gamma mRNA, which peaked at 24 h. When HMC-1 cells were stimulated with PMA (100 nmol/L) for periods of 0-3 days, the cells released IFN-gamma protein, peaking on day 1. These results provide further evidence for the important role of mast cells in the pathogenesis of psoriasis.

Immunocompetent cells in amalgam-associated oral lichenoid contact lesions

Inflammatory cells in amalgam-associated, oral lichenoid contact lesions (OLL) were studied in 19 patients by immunocytochemistry using monoclonal antibodies. Ten of the patients displayed allergic patch test (PT) reactions to several mercury compounds and nine were negative. The immunocytochemical quantification showed a uniform composition of the inflammatory mononuclear cells in the two study groups. The number of HLA-D/DR-positive dendritic cells (P<0.001) and CD1a-positive Langerhans cells (P=0.035) was significantly lower in the PT-negative than PT-positive patients. HLA-D/DR expression on keratinocytes varied from negative to full thickness staining of the epithelium. HLA-D/DR expression in the full thickness of epithelium (3) or through the basal and spinous cell layers (2) was seen in 5 of 8 PT-positive patients, whereas none of the PT-negative patients had this staining pattern (P=0.045). These patients also showed a good clinical response after amalgam removal. Consequently, OLL may represent a true delayed hypersensitivity reaction with a trans-epithelial route of entrance of the metal haptens released from dental restorative materials.

Retinoic acid potentiates TNF-alpha-induced ICAM-1 expression in normal human epidermal keratinocytes

ICAM-1 protein in keratinocytes is thought to contribute to cutaneous inflammatory reactions. Its induction depends-among others-on cytokines such as TNF-alpha, IFN-gamma, IL-1 or on retinoic acid (RA), a key regulator of epidermal homeostasis. We investigated the effect of treatments with TNF-alpha, RA or their combination on ICAM-1 expression on proliferative or differentiating keratinocytes over an 8 day culture period. Basal ICAM-1 levels were undetectable at low (30 microM) and standard (88 microM) Ca2+ and RA alone did not induce ICAM-1. However, at high Ca2+ (1500 microM), ICAM-1 levels were augmented in response to RA-treatment. TNF-alpha induced a transient ICAM-1 increase in NHK, which reached peak-levels 2-4 days post cytokine stimulus. RA potentiated the TNF-alpha-induced ICAM-1 response in all Ca2+-concentrations. This potentiating effect of RA was confirmed at the mRNA level. In summary, our results establish retinoic acid as an enhancer of TNF-alpha-induced ICAM-1 levels in NHK.

Molecular mechanisms of CD8+ T cell-mediated delayed hypersensitivity: implications for allergies, asthma, and autoimmunity

Delayed-type hypersensitivity (DTH) is defined as the recruitment of T cells into tissues to be activated by antigen-presenting cells to produce cytokines that mediate local inflammation. CD8+ T cells are now known to mediate DTH responses in allergic contact dermatitis, drug eruptions, asthma, and autoimmune diseases. This inflammatory effector capability of CD8+ cytotoxic T cells was previously poorly recognized, but there is now considerable evidence that these diseases may be mediated by CD8+ DTH. The difference between CD8+ T cells and CD4+ T cells mediating DTH relates to the molecular mechanisms by which antigens are processed and presented to the T cells. Antigens external to the cell are phagocytosed and processed for presentation on MHC class II molecules (eg, HLA-DR) to CD4+ T cells. In contrast, internal cytoplasmic antigens are processed by the endogenous pathway for presentation on MHC class I molecules (eg, HLA-A, -B, and -C) to CD8+ T cells. External allergens can also enter the endogenous pathway to be presented to CD8+ T cells. These include many contact sensitizers, chemical and protein respiratory allergens, viral antigens, metabolic products of drugs, and autoantigens. The resulting CD8+ T-cell response explains the role of CD8+ T-cell DTH mechanisms in allergic contact dermatitis, asthma, drug eruptions, and autoimmune diseases.

Interferon-gamma-induced ICAM-1 and CD40 expression, complete lack of HLA-DR and CD80 (B7.1), and inconsistent HLA-ABC expression in basal cell carcinoma: a possible role for interleukin-10?

Basal cell carcinomas (BCCs) of the skin show varying degrees of peritumoural inflammatory infiltrate consisting mainly of T cells, but lack an effective T-cell-mediated immune response. This may be caused by the absence of the major histocompatibility complex (MHC) class I and II antigens, intercellular adhesion molecule-1 (ICAM-1), CD40 and CD80 (B7.1). Interferon-gamma (IFN-gamma) is known to induce or up-regulate their expression on epithelial cells, whereas interleukin-10 (IL-10) down-regulates their expression. The induction and up-regulation of HLA-ABC, HLA-DR, ICAM-1, CD40, and CD80 in BCC and normal skin from BCC patients were investigated in a culture system using recombinant human IFN-gamma (rHuIFN-gamma). The levels of IL-10 were determined in the supernatants after culture. The results showed that only ICAM-1 expression was significantly up-regulated on BCC cells. However, in the normal epidermis of BCC patients and in the epidermis overlying the tumour nests, significant up-regulation of ICAM-1, and CD40, and CD80 and slight up-regulation of HLA-DR were observed. No changes in HLA-ABC expression were observed in either normal skin or BCC. High levels of IL-10 were present in the supernatants of BCC biopsies after culture. It may be concluded that it is highly likely that the presence of IL-10 in BCC is directly or indirectly responsible for the complete lack of expression of HLA-DR, ICAM-1, CD40 and CD80 and the inconsistent expression of HLA-ABC on BCC cells in situ and may be a way of escaping immune survillance.

IL-17 Is Produced by Nickel-Specific T Lymphocytes and Regulates ICAM-1 Expression and Chemokine Production in Human Keratinocytes: Synergistic or Antagonist Effects with IFN-γ and TNF-α

IL-17 is a novel T cell-derived cytokine that can regulate the functions of a variety of cell types. In this study, we investigated whether hapten-specific T cells isolated from patients with allergic contact dermatitis (ACD) to nickel produce IL-17 and the effects of IL-17 alone or in combination with IFN-γ or TNF-α on the immune activation of keratinocytes. Skin affected with ACD to nickel and skin-derived, nickel-specific CD4+ T cell lines expressed IFN-γ, TNF-α, and IL-17 mRNAs. Four of seven nickel-specific CD4+ T cell clones positive for the skin-homing receptor, cutaneous lymphocyte-associated Ag, were shown to corelease IL-17, IFN-γ, and TNF-α. In contrast, two nickel-specific CD8+ T cell clones failed to synthesize IL-17. Normal human keratinocytes were found to express constitutively the IL-17 receptor gene. IL-17 specifically and dose-dependently augmented IFN-γ-induced ICAM-1 expression on keratinocytes at both the mRNA and the protein level, whereas HLA-DR, MHC class I, and CD40 levels were not modulated by IL-17. On the other hand, IL-17 alone did not affect ICAM-1 or enhance TNF-α-induced ICAM-1. In addition, IL-17, both directly and in synergism with IFN-γ and/or TNF-α, stimulated synthesis and release of IL-8 by keratinocytes. In contrast, IFN-γ- and TNF-α-induced production of RANTES was markedly inhibited by IL-17, and the synthesis of macrophage chemotactic protein 1 was not changed. Taken together, the results suggest that IL-17 is an important player of T cell-mediated skin immune responses, with synergistic or antagonist effects on IFN-γ- and TNF-α-stimulated keratinocyte activation.

Sphingosylphosphorylcholine is a potent inducer of intercellular adhesion molecule-1 expression in human keratinocytes

We recently reported that the epidermis of patients with atopic dermatitis contains an abnormally expressed sphingomyelin deacylase that yields a large amount of sphingosylphosphorylcholine (SPC) rather than ceramide. In this study, we characterize inflammatory roles of newly discovered chemicals in the epidermis by elucidating biologic effects of SPC on intercellular adhesion molecules-1 (ICAM-I) expression by human keratinocytes in culture in comparison with other sphingolipids. Using fluorescence-activated cell sorter analysis, we found that SPC treatment at concentrations of 10-20 microM significantly enhanced the expression of ICAM-I by cultured human keratinocytes in a dose-dependent manner after incubation for 15-24 h, and, using northern blot analysis, that this was accompanied by increased expression of ICAM-1 mRNA within 4 h of incubation. Transforming necrosis factor-alpha (TNF-alpha) levels in the medium of keratinocytes treated at a 10 microM concentration of SPC were significantly increased by 200%. Furthermore, the SPC-induced ICAM-1 expression was partially abolished by the concomitant addition of anti-TNF-alpha, suggesting a partial autocrine involvement of TNF-alpha in ICAM-1 expression. Assay of mitogen-activated protein kinase revealed that 10 microM SPC induced a rapid activation of mitogen-activated protein kinase in human keratinocytes, including an increase in its phosphorylation within 5 min, which then declined to the baseline control level after 30 min. In contrast, sphingomyelin or sphingosine had no significant potential to activate mitogen-activated protein kinase at the same concentration. These findings suggest that SPC plays an important role in the inflammatory process of epidermis in skin diseases, such as atopic dermatitis, with high expression of sphingomyelin deacylase.

Identification and quantitation of interferon-gamma producing T cells in psoriatic lesions: localization to both CD4+ and CD8+ subsets

Interferon-gamma (IFN-gamma) produced by lesional T cell clones is critical for the induction into G1 of the cell cycle by psoriatic keratinocyte stem cells; however, direct data demonstrating psoriatic lesional T cell subset IFN-gamma expression, and quantitation at a single cell level to calculate in vivo proportions, are lacking. In this study, using flow cytometry of freshly isolated normal and psoriatic lesional T cells from keratome biopsies, we found elevated CD3+, CD4+, and CD8+ T cells in all compartments of psoriatic skin, compared with normals. Using Brefeldin A to induce short-term intracellular accumulation of IFN-gamma in T cells capable of IFN-gamma production, we found that 90% of psoriatic patients have IFN-gamma-producing T cells at a greater proportion of their CD3+ cells than normals, with a mean of 16%+/-3%, as compared with 4%+/-2% in normal epidermis (p = 0.01). Expressed as density in the tissue, the IFN-gamma+ CD3+ cell number in psoriatic epidermis was 97+/-22 per mm2 surface area, as compared with 4.4+/-1.8 per mm2 of normal epidermis (p = 0.002). Thus, the total number of IFN-gamma+CD3+ T cells in the skin of a patient with 20% involvement is estimated to be 3.9 x 10(8). CD4+ and CD8+ IFN-gamma+ T cells were both elevated in psoriatic epidermis (p = 0.04 and p = 0.008, respectively) relative to normal skin. In the dermis, only 44% of patients demonstrated a higher percentage of IFN-gamma-producing T cells than did normals (p = 0.1), possibly indicating dilution, in some patients, by fresh infiltrating T cells. Interleukin-4 was not found by a combination of flow cytometry, reverse transcriptase-polymerase chain reaction, western blot, and immunoprecipitation. In conclusion, a significant portion of lesional T cells in psoriasis are IFN-gamma producing, without interleukin-4. The increased numbers of both IFN-gamma+CD4+ and IFN-gamma+CD8+ T cells indicate that both CD4+ and CD8+ IFN-gamma+ T cells are present in appropriate anatomic locations to sustain the lesional pathology.

Insights into the pathogenesis of psoriasis and psoriatic arthritis

Psoriasis and its related arthritis are chronic inflammatory disorders affecting predominantly the skin and synovium. Although their etiology remains to be established, multiple factors seem to play important roles in their pathogenesis. These environmental (eg, infectious agents and trauma), genetic, and immunologic factors are reviewed in this article.

The pathogenesis of psoriasis and the mechanism of action of tazarotene

The 3 major features of psoriasis--abnormal differentiation of keratinocytes, hyperproliferation of keratinocytes, and infiltration of inflammatory components into the skin--can be quantified by measuring levels of certain biochemical markers. Psoriasis is associated with upregulation or downregulation of several of these markers. Tazarotene helps to normalize the levels of the markers, thereby bringing about clinical improvement.

Interactions between non-immune host cells and the immune system during periodontal disease: role of the gingival keratinocyte

Periodontal disease and inflammatory dermatoses, such as psoriasis, are characterized by the accumulation of dense inflammatory infiltrates immediately beneath the epithelial cell layer of the gingiva and skin, respectively. Dermatologists are increasingly aware that the epidermal keratinocyte probably contributes to inflammatory disease progression by secreting a number of pro-inflammatory cytokines and expressing various adhesion molecules. In psoriatic lesions, it is now believed that epidermal keratinocytes may also act as antigen-presenting cells and participate directly in the superantigenic activation of T-cell clones, some of which may initiate, contribute to, or maintain the disease process. Although the role of the host response in periodontal disease has been extensively studied over the years, very little is known about the contribution of the gingival keratinocyte to the inflammatory response. The available published information is discussed in this review, and we suggest that, like its epidermal counterpart, the gingival keratinocyte may participate actively in the pathogenesis of periodontal disease.

Immunohistochemical investigation of evolving inflammation in lesions of acne vulgaris

The mechanisms involved in the development of inflammation in acne vulgaris have yet to be elucidated. Previous studies have shown that the initial cellular infiltrate in early inflammatory lesions is mononuclear, predominantly CD4 positive T cells. The aims of this study were to investigate the pattern of expression of adhesion molecules and HLA-DR in evolving acne lesions. Forty-nine patients with moderate to severe acne were biopsied following lesion mapping. Lesions were classified according to their duration of inflammation as up to 6 h, from 6 to 24 h, from 24 to 48 h and from 48 to 72 h. The cellular infiltrate was determined using monoclonal antibodies to CDI, CD3, CD4 and CD8. The expression of ICAM-1, E-selectin. VCAM-1 and HLA-DR was determined. Early (6 h) lesions had perivascular CD3 positive T-cell infiltrates which were predominantly CD4 positive. This was associated with vascular expression of ICAM-1, E-selectin, VCAM-1 and HLA-DR. Periductal infiltrates were present in 70% of the early lesions (up to 6 h). The cells were predominantly CD4 positive and associated with a high level of HLA-DR and ICAM-1 expression. Periductal infiltration increased with time and persisted to 72 h. ICAM-1 and HLA-DR were expressed epidermally in early and late lesions. CD1 positive cells were a minor, but consistent element in the perivascular and periductal infiltrates of early and late lesions. There was no statistically significant difference in the levels of expression of E-selectin, VCAM-1, ICAM-1 or HLA-DR for lesions of different duration. The pattern of HLA-DR and adhesion molecule expression plus the nature of the cellular infiltrate supports the hypothesis that inflammation in acne is mediated by CD4 positive T cells.

Epidermal cytokine mRNA expression induced by hapten differs from that induced by primary irritant in human skin organ culture system

Epidermal cells produce various kinds of cytokines and express cell adhesion molecules. To analyze early events which induced in human epidermis by stimulation with various chemicals, we analyzed mRNA of cytokines expressed in epidermis in a human skin organ culture system. After painting haptens, primary irritants or vehicle control on human skin specimens sliced to 1 mm thickness and cut into approximately 5 x 5 mm blocks, the pieces were cultured in serum-free medium. After separating epidermis from dermis, total RNA was extracted and mRNA of cytokines was assessed by the reverse transcriptase-poly-merase chain reaction. Only haptens induced IL-1 beta mRNA at 1-3 hours. TNF-alpha mRNA was induced 9 hours after application of haptens and 1 hour after application of primary irritants. IL-1 alpha mRNA was not induced by either haptens or primary irritants. Thus, cytokine mRNA expression induced by haptens in epidermis differs from that induced by primary irritants.

Interferon-gamma promotes exaggerated cytokine production in keratinocytes cultured from patients with atopic dermatitis

Recent studies suggest that skin keratinocytes from patients with atopic dermatitis (AD) and nonatopic subjects differ in their intrinsic ability to respond to proinflammatory stimuli. In this study keratinocyte cultures established from the normal-looking skin of six adult patients with AD and six healthy, nonatopic control subjects were compared in their response to interferon (IFN)-gamma, a potent proinflammatory lymphokine whose expression is increased in chronic AD lesions. Basal expression of IFN-gamma receptor as well as IFN-gamma-induced membrane expression of HLA-DR and intercellular adhesion molecule (ICAM)-1 were evaluated by flow cytometry. Keratinocyte release of IL-1alpha, IL-1 receptor antagonist (IL-1ra), granulocyte-macrophage colony stimulating factor (GM-CSF), and tumor necrosis factor (TNF)-alpha were measured by ELISA on culture supernatants after treatment with IFN-gamma or medium alone. Expression of membrane IFN-gamma receptor was similar in keratinocytes cultured from nonatopic subjects and subjects with AD. IFN-gamma (10 to 500 U/ml) induced comparable levels of membrane HLA-DR and ICAM-1 in both groups of keratinocytes. In contrast, spontaneous release of IL-1alpha, IL-1ra, GM-CSF, and TNF-alpha was increased in the supernatants of unstimulated keratinocytes from patients with AD compared with keratinocytes from control subjects, with IL-1ra and GM-CSF reaching statistically significant difference. Moreover, IFN-gamma-induced release of all the cytokines tested was much higher for keratinocytes from patients with AD, but the IL-1ra/IL-1alpha ratio for the two groups of keratinocytes was not substantially different, either basally or after IFN-gamma stimulation. The results indicate that keratinocytes from patients with AD are hyperresponsive to IFN-gamma in terms of cytokine release.

Imiquimod, a patient-applied immune-response modifier for treatment of external genital warts

Genital human papillomavirus infection is one of the most common sexually transmitted diseases. Imiquimod is a new agent, an immune-response modifier, that has been demonstrated to have potent in vivo antiviral and antitumor effects in animal models. The present prospective, multicenter, double-blind, randomized, vehicle-controlled trial evaluated the efficacy and safety of daily patient-applied imiquimod for up to 16 weeks for the treatment of external genital warts. Wart recurrence was investigated during a 12-week treatment-free follow-up period. In the intent-to-treat analysis, baseline warts cleared from 49 of 94 (52%) patients treated with 5% imiquimod cream, 13 of 90 (14%) patients treated with 1% imiquimod cream, and 3 of 95 (4%) vehicle-treated patients; the differences between the groups treated with vehicle and imiquimod were significant (P < 0.0001). For subjects who completed the follow-up period, recurrence rates after a complete response were 19% (9 of 48 patients) in the 5% imiquimod cream group, 17% (2 of 12) in the 1% imiquimod cream group, and 0% (0 of 3) in the vehicle-treated group. There were no systemic reactions, although local skin reactions (generally of mild or moderate severity) were common, particularly in the 5% imiquimod cream group. Local reactions caused two patients to discontinue treatment. The most frequently reported local skin reactions were erythema, excoriation or flaking, and erosion. Patient-applied 5% imiquimod cream is effective for the treatment of external genital warts and has a favorable safety profile.

Update on oral lichen planus: etiopathogenesis and management

Lichen planus (LP) is a relatively common disorder of the stratified squamous epithelia, which is, in many ways, an enigma. This paper is the consensus outcome of a workshop held in Switzerland in 1995, involving a selection of clinicians and scientists with an interest in the condition and its management. The oral (OLP) eruptions usually have a distinct clinical morphology and characteristic distribution, but OLP may also present a confusing array of patterns and forms, and other disorders may clinically simulate OLP. Lesions may affect other mucosae and/or skin. Lichen planus is probably of multifactorial origin, sometimes induced by drugs or dental materials, often idiopathic, and with an immunopathogenesis involving T-cells in particular. The etiopathogenesis appears to be complex, with interactions between and among genetic, environmental, and lifestyle factors, but much has now been clarified about the mechanisms involved, and interesting new associations, such as with liver disease, have emerged. The management of lichen planus is still not totally satisfactory, and there is as yet no definitive treatment, but there have been advances in the control of the condition. There is no curative treatment available; immunomodulation, however, can control the condition. Based on the observed increased risk of malignant development, OLP patients should be offered regular follow-up examination from two to four times annually and asked to report any changes in their lesions and/or symptoms. Follow-up may be particularly important in patients with atrophic/ulcerative/erosive affections of the tongue, the gingiva, or the buccal mucosa. Much more research is required into the genetic and environmental aspects of lichen planus, into the premalignant potential, and into the possible associations with chronic liver, and other disorders. More clinical studies are required into the possible efficacy of immunomodulatory drugs such as pentoxifylline and thalidomide.

In situ expression of cell adhesion molecules in chronic gastritis with Helicobacter pylori infection

Helicobacter pylori infection of the stomach results in acute inflammation followed by chronic inflammation, but the mechanism is unknown. Adhesion molecules such as ICAM-1, Mac-1, and LFA-1 may help regulate interactions of immune cells and inflammatory cells. We used immunohistochemistry to locate these molecules in the gastric mucosa of patients with chronic gastritis arising from H. pylori infection. Biopsy specimens were taken from five H. pylori-negative healthy volunteers and 20 H. pylori-positive patients with chronic gastritis for immunohistochemical studies of adhesion molecules. In the gastric mucosa of patients with H. pylori-associated chronic gastritis, ICAM-1 expression was prominent in most of the vessels and inflammatory cells, such as lymphocytes and granulocytes, in the lamina propria. However, no intraepithelial lymphocytes and surface epithelial cells expressed ICAM-1. Antigen-presenting cells (APCs), such as macrophages, expressed ICAM-1 as well as HLA-DR antigen. LFA-1 and Mac-1 were strongly expressed in these immune and inflammatory cells. The number of vascular endothelial cells positive for P-selectin was also greater in H. pylori-positive mucosa. The expression of these molecules decreased remarkably after successful eradication of H. pylori. In conclusion, ICAM-1 is the predominant form among the cell adhesion molecules that are expressed in response to chronic H. pylori infection. The increased expression of ICAM-1 is linked with massive infiltration of inflammatory cells that express LFA-1 and Mac-1, and also with APCs that express HLA-DR, suggesting that ICAM-1 exerts a key role in immuno-inflammatory responses in gastric mucosa of patients with H. pylori-associated gastritis.

Expression of interferon-gamma receptors and interferon-gamma-induced up-regulation of intercellular adhesion molecule-1 in basal cell carcinoma; decreased expression of IFN-gamma R and shedding of ICAM-1 as a means to escape immune surveillance

The peritumoural inflammatory infiltrate in basal cell carcinoma (BCC) of the skin consists mainly of T lymphocytes which hardly invade the tumour nests. The absence of intercellular adhesion molecule-1 (ICAM-1) on BCC cells may explain the lack of tumour-infiltrating cells and the lack of an active cell-mediated immune response in this tumour. In this study, the induction of ICAM-1 was investigated in BCC biopsies using recombinant human interferon-gamma (rHuIFN-gamma). The expression of interferon-gamma receptors (IFN-gamma R) in the biopsies was also investigated. The results showed that BCC cells expressed ICAM-1 after incubation with rHuIFN-gamma, but to a lesser degree than normal epidermal cells. The levels of shed ICAM-1 were significantly increased in the culture supernatants of tumour biopsies compared with those from normal skin biopsies, after culturing in the presence of rHuIFN-gamma. The expression of IFN-gamma R was significantly decreased on the tumour cells compared with the overlying epidermis. The decreased expression of IFN-gamma R on the tumour cells and the shedding of ICAM-1 into the peritumoural stroma may be a plausible mechanism by which the tumour cells are protected against an active cell-mediated immune response.

Treatment of genital warts with an immune-response modifier (imiquimod)

BACKGROUND

Genital warts are a common sexually transmitted disease caused by human papillomavirus. Imiquimod is a novel immune-response modifier capable of inducing a variety of cytokines, including interferon alfa, tumor necrosis factor-alpha, as well as interleukins 1, 6, and 8. In animal models imiquimod has demonstrated antiviral, antitumor, and adjuvant activity. In vitro, imiquimod has no antiviral or antitumor activity.

OBJECTIVE

Our purpose was to determine the safety and efficacy of topical imiquimod for the treatment of external genital warts.

METHODS

This prospective double-blind, placebo-controlled, parallel design clinical trial was performed in three outpatient centers, a public health clinic, a university-based clinic, and a private practice. One hundred eight patients with external genital warts (predominantly white men) were entered into the trial. Fifty-one patients were randomly selected to receive 5% imiquimod cream; 57 patients were randomly chosen to receive placebo cream. Study medication was applied three times weekly for up to 8 weeks. Patients whose warts cleared completely were observed for up to 10 weeks to determine recurrence rates.

RESULTS

In the intent-to-treat analysis, the warts of 37% (19 of 51) of the imiquimod-treated patients and 0% (0 of 57) of the placebo group cleared completely (p < 0.001). In addition, many patients experienced a partial response. A reduction in baseline wart area of 80% or more was observed in 62% of imiquimod-treated patients (28 of 45) and 4% of the placebo group (2 of 50) (p < 0.001); a 50% reduction or more in wart area was noted in 76% of imiquimod-treated patients (34 of 45) and 8% of placebo recipients (4 of 50) (p < 0.001). Of imiquimod-treated patients whose warts cleared completely and who finished the 10-week follow-up period, 19% (3 of 16) experienced recurrences of warts. Imiquimod-treated patients experienced a significantly greater number of local inflammatory reactions than the placebo group. Symptoms and signs associated with the local inflammatory reactions included itching (54.2%), erythema (33.3%), burning (31.3%), irritation (16.7%), tenderness (12.5%), ulceration (10.4%), erosion (10.4%), and pain (8.3%). There were no differences in systemic reactions or laboratory abnormalities between treatment groups.

CONCLUSION

Topical 5% imiquimod cream appears to have a significant therapeutic effect in the treatment of external genital warts.

Vascular activation of adhesion molecule mRNA and cell surface expression by ionizing radiation

During cutaneous inflammatory reactions the recruitment of circulating leukocytes into the tissue critically depends on the regulated expression of endothelial cell adhesion molecules (CAMs). Various proinflammatory stimuli upregulate endothelial CAMs, including cytokines and UV irradiation. We have investigated the effects of ionizing radiation (IR) on endothelial CAM expression. Organ cultures of normal human skin as well as cultured human dermal microvascular endothelial cells (HDMEC) were exposed to IR. Expression of three major endothelial CAMs was studied in skin organ cultures by immunohistochemistry and in cell culture by Northern blot analysis and flow cytometry. In skin organ cultures vascular immunoreactivity for ICAM-1, E-selectin, and VCAM-1 was strongly induced 24 h after exposure to 5 or 10 Gy of IR, while immunoreactivity for CD31/PECAM-1, a constitutively expressed endothelial cell adhesion molecule, remained unchanged. In cultured HDMEC IR upregulated ICAM-1, VCAM-1, and E-selectin mRNAs and cell surface expression in a time- and dose-dependent fashion. Cellular morphology and viability remained unaltered by IR up to 24 h postirradiation. This study characterizes microvascular activation of adhesion molecule expression in response to ionizing radiation in a clinically relevant IR dose range. The findings also underscore the ability of endothelial cells to integrate environmental electromagnetic stimuli.

Cetirizine and hydrocortisone differentially regulate ICAM-1 expression and chemokine release in cultured human keratinocytes

BACKGROUND

Cetirizine is a H1 histamine antagonist which possesses anti-inflammatory properties through inhibition of leucocyte recruitment and activation, and reduction of ICAM-1 expression on mucosal epithelial cells. No studies have addressed the potential anti-inflammatory activities of cetirizine on skin keratinocytes.

OBJECTIVES

Cetirizine and hydrocortisone were compared in their capacity to counteract human keratinocytes activation by IFNgamma. In particular, expression of immuno-modulatory membrane molecules and chemokine release have been examined.

METHODS

Keratinocyte cultures established from normal skin of healthy donors were activated by IFNgamma (100-500 U/mL) in the absence or presence of cetirizine (10(-3)-10(3) microM) or hydrocortisone (10(-3)-10(2) microM), and tested for expression of ICAM-1, HLA-DR, MHC class I and CD40 as well as for release of RANTES, IL-8, macrophage chemotactic protein-1 (MCP-1) and granulocyte macrophage-colony stimulating factor (GM-CSF).

RESULTS

Cetirizine at high concentrations (10(2)-10(3) microM) markedly inhibited IFNgamma-induced expression of membrane ICAM-1, HLA-DR and up-regulation of MHC class I, but had no effect on CD40 expression. In contrast, hydrocortisone (10(2) microM) enhanced IFNgamma-induced membrane ICAM-1, reduced expression of HLA-DR and did not alter expression of MHC class I and CD40. Consistently, high doses of cetirizine decreased, whereas hydrocortisone increased, soluble ICAM-1 levels in the supernatants of IFNgamma-treated keratinocytes. The inhibiting and stimulating effects of cetirizine and hydrocortisone, respectively, on ICAM-1 expression were confirmed at the mRNA level by Northern blot analysis. Finally, cetirizine, but not hydrocortisone, inhibited the release of MCP-1 and RANTES from IFNgamma-stimulated keratinocytes. In contrast, hydrocortisone, but not cetirizine, reduced GM-CSF and IL-8 release.

CONCLUSIONS

The results indicate that cetirizine has the capacity to block the IFNgamma-induced activation of keratinocytes, and thus can exert important regulatory effects on TH1 cell-mediated immune responses in the skin. The high doses required for evidencing these activities suggest the potential benefits of a topical use of cetirizine.

Adhesion molecules in vernal keratoconjunctivitis

AIMS/BACKGROUND

Adhesion molecules play a key role in the selective recruitment of different leucocyte population to inflammatory sites. The purpose of the present study was to investigate the presence and distribution of adhesion molecules in the conjunctiva of patients with vernal keratoconjunctivitis (VKC).

METHODS

The presence and distribution of adhesion molecules were studied in 14 conjunctival biopsy specimens from seven patients with active VKC and in four normal conjunctival biopsy specimens. We used a panel of specific monoclonal antibodies (mAbs) directed against intercellular adhesion molecule-1 (ICAM-1), intercellular adhesion molecule-3 (ICAM-3), lymphocyte function associated antigen-1 (LFA-1), very late activation antigen-4 (VLA-4), vascular cell adhesion molecule-1 (VCAM-1), and endothelial leucocyte adhesion molecule-1 (ELAM-1) In addition, a panel of mAbs were used to characterise the composition of the inflammatory infiltrate.

RESULTS

In the normal conjunctiva, ICAM-1 was expressed on the vascular endothelium only, LFA-1 and ICAM-3 on epithelial and stromal mononuclear cells, and VLA-4 on stromal mononuclear cells. The expression of VCAM-1 and ELAM-1 was absent. The number of cells expressing adhesion molecules was found to be markedly increased in all VKC specimens. This was concurrent with a heavy inflammatory infiltrate. Strong ICAM-1 expression was induced on the basal epithelial cells, and vascular endothelial cells. Furthermore, ICAM-I was expressed on stromal mononuclear cells. LFA-1 and ICAM-3 were expressed on the majority of epithelial and stromal infiltrating mononuclear cells. VLA-4 expression was noted on stromal mononuclear cells. Compared with controls, VKC specimens showed significantly more ICAM-3+, LFA-3+, LFA-1+, and VLA-4+ cells. VCAM-1 and ELAM-1 were induced on the vascular endothelial cells.

CONCLUSIONS

Increased expression of adhesion molecules may play an important role in the pathogenesis of VKC.

Adhesion of leukocytes to dermal endothelial cells is induced after single-dose, but reduced after repeated doses of UVA

Approximately 20-50% of ultraviolet A (UVA) irradiation delivered to the skin surface may reach the human dermal microvascular endothelial cells (HDMEC) that play a pivotal role in cellular inflammatory tissue; however, the pathophysiologic role of HDMEC in UVA-induced skin changes is largely unknown. Based on previous in vivo and in vitro studies revealing UVA-induced expression of endothelial adhesion molecules, we studied isolated HDMEC under various conditions in order to further delineate the impact of UVA on these cells. The expression of cell adhesion molecules was determined by flow cytometry and the resulting changes of stable adhesion of leukocytes to endothelial cells were quantitated for granulocytes, lymphocytes, and monocytes using a newly developed multicellular adhesion assay. Additionally, antibody blocking experiments were performed to delineate the role of individual cell adhesion molecules in UVA-induced leukocyte adherence. High-dose polychromatic UVA (25 J per cm2, maximal emission at 375 nm) induced intercellular adhesion molecule-1 and E-selectin with different kinetics but correlating the adhesion of leukocyte subsets. This effect subsided, however, in the course of 3-6 daily applied UVA doses. Moreover, pro-inflammatory cytokine challenge by tumor necrosis factor-alpha and interleukin-1-alpha resulted in significantly weaker induction of intercellular adhesion molecule-1 and E-selectin in repeatedly UVA-exposed HDMEC. Differential quantitation of peripheral blood derived granulocytes, lymphocytes, and monocytes revealed reduced adhesion particularly of lymphocytes followed by monocytes and granulocytes compared with leukocyte adhesion to nonirradiated but cytokine-stimulated HDMEC. It is concluded that UVA substantially influences endothelial cell adhesion molecules expression and thus directly interferes with leukocyte adhesion to endothelial cells. Divergent UVA-induced effects in this respect can be attributed to the mode of UV exposure as well as to the condition of endothelial cells prior to UVA exposure.

Immunopathogenesis of oral lichen planus and recurrent aphthous stomatitis

Oral mucosal bullous/desquamative/ulcerative diseases involve immunopathological mechanisms that account for loss of adhesion between contiguous keratinocytes or to structures within the basal lamina. Some are antibody mediated, in which specific adhesion molecules of the desmosome, hemidesmosome, and basement membrane become antigenic targets. Oral lichen planus and recurrent apthous ulcers, although manifesting disparate clinical appearances and natural history, share immunopathological features that involve T cell-mediated immunity. Although the antigens, haptens, or autoantigens are not usually apparent, current research poses the hypothesis that both of these common oral mucosal diseases are a delayed-type hypersensitivity or cell-mediated response to an antigenic stimulus residing within the epithelium. This article reviews the research evidence for this hypothesis.

Characterization of T-cell subsets infiltrating post-burn hypertrophic scar tissues

In this study, skin-infiltrating cells were characterized in both the active and remission phases of post-burn hypertrophic scar biopsies. Immunohistochemistry examination of active phase samples showed an abundant presence of Langerhans cells, T cells, macrophages, a low presence of natural killer cells and the lack of B lymphocytes. In active hypertrophic scars T lymphocytes infiltrate deep into the superficial dermis and are also observed in the epidermis: CD3+ cells were present at about 222 +/- 107 per 0.25 mm2. In particular the analysis of lymphocyte subpopulations showed that CD4+ T cells predominate in the dermis as well as in the epidermis of active hypertrophic scars whereas CD8+ cells were less well represented (CD4/CD8 ratio is 2.06). This distribution was also shown in remission phase samples and in normotrophic scar specimens, although the lymphocyte number was significantly lower. Approximately 70 per cent of T lymphocytes present in the tissue involved in active phase hypertrophic scar samples were activated (positive with anti-HLA-DR and IL-2 receptor antibodies) which is significantly higher than remission phase hypertrophic and normotrophic scars, in which positivity was 40 and 38 per cent, respectively. Upon activation, the lesional lymphocytes release several cytokines, locally and transiently, that interact with specific receptors in response to different stimulation. Central to the immune hypothesis of hypertrophic scars is that some of the T-cell lymphokines act on keratinocytes, fibroblasts and other cell types to induce changes characteristic of these scars. The presence and close proximity of activated T lymphocytes and antigen-presenting cells of various phenotypes in both the epidermis and dermis of hypertrophic tissues provides strong circumstantial evidence of a local immune response. However, the manner in which T cells achieve and maintain their activated state in hypertrophic tissues is not yet known, and both antigen-dependent and independent mechanisms may contribute.

Characterization of the cutaneous inflammatory infiltrate in canine atopic dermatitis

Sections from lesional atopic, clinically normal atopic, and normal canine skin were investigated by light microscopy and an immunoperoxidase method using monoclonal antibodies specific for canine leukocyte antigens. We confirmed that skin-infiltrating cells of canine atopic dermatitis are constituted of mast cells, dendritic antigen-presenting cells, memory helper T-lymphocytes, low numbers of eosinophils and neutrophils, and rare B-lymphocytes. The presence of epidermal eosinophil microaggregates and clustered Langerhans' cells supports the hypothesis of epidermal allergen contact. The hyperplasia of epidermal T-cells expressing the gamma/delta T-cell receptor appears specific to canine atopic dermatitis compared with its human counterpart. This finding could be explained by an interspecies difference in skin immune systems or, alternatively, by an active participation of these epitheliotropic gamma/delta T-cells in the cutaneous allergic immune response in dogs. The paucity of dermal neutrophils in spontaneous lesions of canine atopic dermatitis is notably different from the neutrophil-rich late-phase reactions provoked by intradermal allergen injections in allergic dogs. This difference in the cellular infiltrate probably results from variations in the immune reaction between single and repeated allergen exposure as well as epidermal versus dermal antigen contact.

Dental innervation: functions and plasticity after peripheral injury

Oral tissues including the periodontal ligament, gingiva, and tooth pulp have a relatively dense sensory innervation and a rich vascular supply. Teeth and supporting tissues are susceptible to tissue injury and inflammation, partly due to lack of collateral blood and nerve supply and to their low compliance. This review focuses on dental nerve functions and adaptive changes in the trigeminal ganglion and tooth pulp after peripheral injuries. An overview of the peptidergic innervation of oral tissues is presented, followed by a discussion of plasticity in neuropeptide expression in trigeminal peripheral neurons after local insults to teeth and peripheral nerve injuries. The functional implications of these adaptive changes are considered, with special reference to nerve regeneration, inflammation, and hemodynamic regulation.

In situ hybridization analysis of ICAM-1 (CD54) mRNA on conjunctival epithelium during allergic inflammation

BACKGROUND

The intercellular adhesion molecule ICAM-1 has been detected by immunohistochemical methods on epithelial cells of the conjunctiva and nose during allergic inflammation.

OBJECTIVE

The aim of the present study was to evaluate whether ICAM-1 expression on conjunctival epithelium derives from endogenous synthesis or is merely due to passive uptake of soluble ICAM-1 released from inflammatory cells.

METHODS

In situ hybridization was performed using a 3' end dygoxygenin-labelled specific DNA oligonucleotide probe on fixed conjunctival smears from allergic subjects challenged with, or naturally exposed to the allergen, and from healthy subjects. Immunocytochemistry for ICAM-1 was performed by alkaline phosphatase antialkaline phosphatase.

RESULTS

In allergic patients, both naturally exposed to the allergen and after specific challenge, a clear hybridization pattern on epithelial cells was apparent. Out of allergen exposure, some symptomfree pollinosic subjects, as well as a few healthy volunteers showed mild ICAM-1 mRNA cytoplasmic staining in the absence of immunohistochemically detectable ICAM-1. This finding may explain the very early appearance of ICAM-1 on conjunctival epithelium following specific challenge in allergic individuals.

CONCLUSIONS

These results indicate that the presence of ICAM-1 on conjunctival epithelium during allergic inflammation derives from endogenous synthesis and not from uptake of soluble ICAM-1.

The regulation of CD11b integrin levels on human blood leukocytes and leukotriene B4-stimulated skin by a specific leukotriene B4 receptor antagonist (LY293111)

CD11b is part of the beta2-integrin Mac-1 and plays an important role in neutrophil adhesion. Leukotriene B4 (LTB4) is an active upregulator of neutrophil CD11b-expression, acts as a potent chemoattractant to neutrophils and is also known to upmodulate epidermal proliferation. We performed a placebo-controlled study on LY293111, an oral LTB4 receptor antagonist. Twenty healthy male volunteers were randomised over three treatment groups that received placebo, 48 mg, or 200 mg drug twice daily for 10 days. Before and after treatment, flow cytometrical CD11b assessment was performed on in vitro LTB4-stimulated peripheral blood neutrophils. Additionally, skin biopsies were taken at 24 and 72 h after epicutaneous LTB4 application, before and after treatment. The effects on skin were assessed immunohistochemically using various markers. All observed effects were dose related. CD11b upregulation on blood neutrophils was significantly suppressed in both treatment groups compared to placebo. In skin, a significant suppression of inflammation and hyperproliferation occurred. Pronounced inhibition was observed on neutrophil migration into the epidermis and the inflammatory infiltrate was decreased. A similar but weaker response was seen in the dermis. The number of cycling cells as well as suprabasal keratin-16 expression were decreased in both treatment groups. LY293111 proved to be a potent inhibitor of LTB4-induced cutaneous inflammation and hyperproliferation. The potent antiinflammatory effect in vivo and the fact that in the present study the compound showed no clinically significant side effects make it an interesting drug in the future treatment of inflammatory conditions predominated by neutrophils.

Immunohistochemical analysis of intercellular adhesion molecule-1 expression in human gastric adenoma and adenocarcinoma

In this study, we examined the distribution of intercellular adhesion molecule-1 (ICAM-1) in gastric adenomas and carcinomas immunohistochemically at the light and electron microscopic levels. ICAM-1 was expressed on tumour cells in 12 of 28 gastric carcinomas and in 3 of 11 adenomas but not on most normal gastric epithelial cells. ICAM-1 was localized on luminal sites of neoplastic glands in adenomas and in intestinal-type carcinomas, and rarely on the surface of tumour cells of diffuse carcinomas. Expression of ICAM-1 on the tumour cells was more frequent in intestinal-type than diffuse carcinomas (P < 0.005). At the ultrastructural level, ICAM-1 was present prominently on the apical membrane and weakly on the lateral surface of the tumour cells of the intestinal-type carcinoma and also localized on the perinuclear membrane and the membrane of the endoplasmic reticulum of cancer cells. There was no significant association between ICAM-1 expression and HLA antigen expression or the number of infiltrating lymphocyte subsets. These results may implicate the synthesis of ICAM-1 by gastric cancer cells, but the expression is infrequent and may not be sufficient for host immune surveillance of the tumour cell.

Transgenic mice expressing IFN-gamma in the epidermis have eczema, hair hypopigmentation, and hair loss

To study the role of IFN-gamma in the pathogenesis of inflammatory skin diseases, we used the involucrin promoter to overexpress IFN-gamma in the suprabasal layers of transgenic mouse epidermis. IFN-gamma mRNA and protein were readily detectable in the skin but not in the blood. Mice exhibited striking hypopigmentation of the hair due to a reduced abundance of DOPA-positive melanocytes. Severely affected mice had reddened skin, growth retardation, hair loss, and flaky skin lesions. Keratinocyte proliferation was increased, and there was epidermal thickening with spongiosis and parakeratosis. Suprabasal beta1 integrin expression and induction of keratin 17 in interfollicular epidermis provided evidence of perturbed differentiation. IFN-gamma receptor expression was reduced, and there was induction of ICAM-1 and MHC class II molecules on the surface of transgenic keratinocytes. The skin of severely affected mice was characterized by a dermal infiltrate of T lymphocytes and macrophages/monocytes, but the epidermis was almost devoid of Langerhans cells and T lymphocytes. The number of Langerhans cells in the lymph nodes was increased in the transgenics, and autoantibodies to keratinocytes were produced. Transgenic mice showed an increased contact hypersensitivity reaction to topical application of DNFB. We conclude that constitutive IFN-gamma expression in the epidermis results in a form of eczema resembling contact dermatitis and in a profound contact hypersensitivity reaction.

Fixed drug eruption caused by iopamidol, a contrast medium

We report a patient who developed a fixed drug eruption caused by the contrast medium, Iopamidol. We diagnosed it by her episode pattern and the results of patch tests. This substance has not been previously implicated as a cause of fixed drug eruption. Immunohistochemical studies showed Fas expression in keratinocytes of the lesion, but not in the uninvolved skin. This finding may explain the preferential localization of fixed drug eruption.

Pervanadate mimics IFNgamma-mediated induction of ICAM-1 expression via activation of STAT proteins

Differential expression of intercellular adhesion molecule-1 (ICAM-1) in the epidermis plays a critical role in the regulation of cutaneous inflammation, immunologic reactions, and tissue repair. Transcriptional upregulation of ICAM-1 in response to interferon-gamma (IFNgamma) occurs through a palindromic response element pIgammaRE. pIgammaRE is homologous to IFNgamma-activated sequences, which bind to tyrosine phosphorylated members of the transcription factor family known as signal transducers and activators of transcription (STAT). The importance of tyrosine phosphorylation events in the STAT pathway led us to investigate the effect of the protein tyrosine phosphatase inhibitor, pervanadate, on ICAM-1 expression. We show that treatment of A431 cells and human keratinocytes with pervanadate stimulates protein complex formation on pIgammaRE in a time- and concentration-dependent manner. As demonstrated by mobility supershift assays, the pervanadate-stimulated complex is similar to the IFNgamma-stimulated complex and contains Stat1. Pervanadate treatment also led to an increase in overall protein tyrosine phosphorylation and phosphorylation of Stat1, as well as the subsequent increase in ICAM-1 mRNA and cell surface protein levels. These data show that pervanadate can mimic each step in the IFNgamma-mediated pathway leading to ICAM-1 expression, demonstrate the ability of a pharmacologic agent to bypass the standard cytokine-receptor interaction required for increased ICAM-1 expression, and emphasize the importance of protein tyrosine phosphatases and protein tyrosine kinases in mediating inflammatory responses in the skin.

Folliculotropic mycosis fungoides with large-cell transformation presenting as dissecting cellulitis of the scalp

Follicular mycosis fungoides (MF) is a rare variant of cutaneous T-cell lymphoma (CTCL) in which malignant lymphocytes preferentially infiltrate hair follicles. This report describes a patient with follicular mycosis fungoides presenting in a manner similar to dissecting cellulitis of the scalp with nonhealing, draining nodular lesions. Follicular mucinosis associated with folliculotropic mycosis fungoides resulted in follicular disruption and deep dissecting cellulitis. Large-cell transformation of CTCL was present in the initial diagnostic scalp and axillary lymph node specimens. The patient died from progressive CTCL 9 months following initial diagnosis despite electron beam radiation, topical mechlorethamine, interferon-alpha, and systemic chemotherapy. This case indicates that large-cell transformation of folliculotropic mycosis fungoides is an aggressive form of CTCL, and that folliculotropic mycosis fungoides can give rise to lesions which resemble dissecting cellulitis of the scalp. Upregulation of intercellular adhesion molecule-1 (ICAM-1) on follicular epithelium adjacent to lymphocyte function-associated antigen-1 (LFA-1)-positive folliculotropic lymphoma cells in this report provides insight into lymphocyte homing mechanisms in folliculotropic MF.

Up-regulation of class II major histocompatibility complex and intercellular adhesion molecule 1 expression on scleroderma fibroblasts and endothelial cells by interferon-gamma and tumor necrosis factor alpha in the early disease stage

OBJECTIVE

To investigate the expression patterns of interferon-gamma (IFN gamma) and tumor necrosis factor alpha (TNF alpha), both of which are potent inducers of class II major histocompatibility complex (MHC) and intercellular adhesion molecule 1 (ICAM-1) expression, and their codistribution with HLA-DR and ICAM-1 in skin lesions, cultured fibroblasts, and peripheral blood mononuclear cells (PBMC) of systemic sclerosis (SSc) patients in different stages of disease.

METHODS

Investigations were carried out using immunohistochemistry studies, reverse transcriptase-polymerase chain reaction, dot-blot hybridization, and cytometric analysis. Serum levels of TNF alpha were determined by enzyme-linked immunosorbent assay.

RESULTS

In the early inflammatory stage of SSc, class II MHC and ICAM-1 expression could be detected on most endothelial cells and on fibroblasts located especially in perivascular areas surrounded by infiltrating lymphocytes, which belong to the T helper 1 phenotype expressing IFN gamma and TNF alpha. In this early disease stage, an enhanced expression of TNF alpha on cultured dermal fibroblasts and PBMC, as well as elevated serum titers of soluble TNF alpha, could be found.

CONCLUSION

These data suggest that class II MHC antigens and ICAM-1 on fibroblasts and endothelial cells are induced by IFN gamma and TNF alpha in an early stage of SSc after the influx of mononuclear-cells, and may be important in the putative autoimmune response and in the perpetuation of fibrotic processes in SSc.

Immunologic aspects of dermal and oral lichen planus: a review

There have been many investigations, both experimental and epidemiologic, of the forms of LP affecting the skin and oral mucosae. These studies have provided a varied range of hypotheses to explain not only the factors determining susceptibility to and onset of this disease, but also the immunologic mechanisms leading to the pathosis with which LP is associated. Much progress has been made, especially through in vitro studies, regarding detailed aspects of the immunology of LP. However, data is often conflicting or incomplete. In this review we attempt to bring together the currently available data regarding the immunologic basis of LP.

Induction of hapten-specific tolerance of human CD8+ urushiol (poison ivy)-reactive T lymphocytes

The interaction of CD28 with B7 molecules (CD80 or CD86) is an essential second signal for both the activation of CD4+ T cells through the T-cell receptor and the prevention of anergy. We studied the requirement of hapten-specific human CD8+ cells for CD28 co-stimulation in recognition of hapten, and anergy induction. Urushiol, the immunogenic hapten of poison ivy (Toxicodendron radicans), elicits a predominantly CD8+ T-cell response. Autologous PBMC were pre-incubated with urushiol prior to fixation by paraformaldehyde. Fixed antigen-presenting cells were unable to present urushiol to human CD8+ urushiol-specific T cells. Addition of anti-CD28, however, overcame this antigen-presenting defect, enabling CD8+ cells to proliferate. Fixation of antigen-presenting cells prevents upregulation of B7, and addition of anti-CD28 substitutes for this signal. Proliferation of CD8+ T cells in response to urushiol was blocked by CTLA4Ig, a recombinant fusion protein that blocks CD28/B7 interactions. Preincubation of urushiol-specific CD8+ cells with fixed PBMC + urushiol for 7 d induced anergy. Anergic CD8+ cells were viable and able to proliferate in response to IL-2, but not in response to urushiol. Induction of anergy required the presence of urushiol, and pre-incubation with irradiated PBMC + urushiol did not have this effect. It is proposed that anergy was induced by presentation of urushiol by fixed PBMC, in the absence of adequate co-stimulation signals. Induction of anergy by blocking of co-stimulation could potentially induce clinical hyposensitization to haptens.

Immunotherapy of Psoriasis

Background:

Psoriasis is a common inflammatory skin disease, characterized by epidermal keratinocyte hyperproliferation and an inflammatory infiltrate. Current research indicates that epidermal hyperproliferation is, in part, dependent upon the milieu of cytokines and growth factors produced chiefly by T cells within the infiltrate and that the T cells play a central role in the pathogenesis of psoriasis.

Objective:

Recent developments in the treatment of psoriasis are discussed in the context of current understanding of the pathogenesis of this condition.

Conclusion:

Significant advances are being made in the treatment directed against these specific immunologic aberrations. Efficacy of immunosuppressive agents such as cyclosporine, FK506 (tacrolimus), anti-CD4 monoclonal antibodies, and IL-2 fusion-toxin in the treatment of psoriasis underscore its probable immune basis. Highly specific treatment directed against cytokines, angiogenesis, and adhesion molecules remains experimental, but shows promise for safer systemic treatment in the future.

Differential expression of the major histocompatibility antigens and ICAM-1 on bile duct epithelial cells in biliary atresia

Aberrant expression on biliary epithelial cells of the major histocompatibility complex (MHC) antigens in association with adhesion molecule intercellular adhesion molecule-1 (ICAM-1) may be crucial to the immunopathogenesis of biliary atresia. The patterns of MHC class I and II expression in relation to ICAM-1 expression as well as the associated lymphocyte subpopulations were studied in frozen section liver biopsies from six infants with biliary atresia. Intense ICAM-1 expression was found on all ductal epithelial cells in association with MHC I. No ductal epithelial cells demonstrated MHC II expression. Lymphocyte populations within the portal tracts all expressed LFA-1 and were predominantly CD4 positive (> 70%). CD8 positive cells accounted for less than 30%. The expression of ICAM-1 appears to be important in the pathogenesis of biliary atresia but is not linked to the expression of MHC II determinants. This result suggests that different regulatory mechanisms govern the expression of these important immunological receptors on biliary epithelial cells.

T-cell-mediated immunity to lymphocytic choriomeningitis virus in beta2-integrin (CD18)- and ICAM-1 (CD54)-deficient mice

The T-cell response to lymphocytic choriomeningitis virus was studied in mice with deficient expression of beta2-integrins or ICAM-1. In such mice, the generation of virus-specific cytotoxic T lymphocytes was only slightly impaired and bystander activation was as extensive as that observed in wild-type mice. T-cell-mediated inflammation, assessed as primary footpad swelling and susceptibility to intracerebral infection, was slightly compromised only in beta2-integrin-deficient mice. However, adoptive immunization of mutant mice soon after local infection did reveal a reduced capacity to support the inflammatory reaction, indicating that under conditions of more limited immune activation both molecules do play a role in formation of the inflammatory exudate. Finally, virus control was found to be somewhat impaired in both mutant strains. In conclusion, our results indicate that although LFA-1-ICAM-1 interaction is important for certain aspects of the T-cell-mediated response to viruses, T-cell activation is surprisingly intact in these mutant mice, indicating extensive functional redundancy within cell interaction molecules.