Recombinant gamma interferon increases the binding of peripheral blood mononuclear leukocytes and a Leu-3+ T lymphocyte clone to cultured keratinocytes and to a malignant cutaneous squamous carcinoma cell line that is blocked by antibody against the LFA-1 molecule

Pathological crosstalk in vitro between T lymphocytes and lesional keratinocytes in psoriasis: necessity of direct cell-to-cell contact

Psoriasis, a chronic autoimmune-related skin disease, involves both immune and non-immune cells like T cells and keratinocytes. This study investigates the regulatory role of T cells-keratinocyte interactions during psoriasis on immune factors production. Cytokines and chemokines were evaluated by multiplex and ELISA assays in an in vitro model of co-culture of keratinocytes with T lymphocytes. Keratinocytes were from psoriatic skin lesions or healthy skin. T lymphocytes were from healthy volunteers. Psoriatic keratinocytes (PKs) alone generated concentrations of tumor necrosis factor (TNF)-α, interleukin (IL)-6, granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-1β, IL-8, monocyte chemotactic protein (MCP)-1, interferon-γ-induced protein 10 kDa (IP-10) and vascular endothelial growth factor (VEGF) higher than those produced by healthy keratinocytes (HKs). In contrast, IL-1α and IL-Ra production was reduced in PKs. Normal T cells, which had no effect on HKs, increased the production of TNF-α, IL-6, GM-CSF, IL-8, MCP-1 and IP-10 by PKs, but did not influence PK production of IL-1β, IL-1α, IL-Ra and VEGF. The most striking effects were obtained with PK- and IL-2-stimulated T lymphocytes: most of the above cytokines and chemokines were greatly upregulated, except IL-1β and VEGF that were decreased or unchanged, respectively. In addition, fractalkine was overproduced in this latter condition only. Our results indicate (1) a functional interaction between keratinocytes and T lymphocytes that requires a direct cellular contact, and (2) a reciprocal influence that depends on cytokine and chemokine types. In conclusion, lesional keratinocytes from psoriasis vulgaris alter functions of normal T lymphocytes that conversely modulate these keratinocytes.

Efficacy of the fully human monoclonal antibody MOR102 (#5) against intercellular adhesion molecule 1 in the psoriasis-severe combined immunodeficient mouse model

BACKGROUND

Psoriasis is considered as a chronic immune-mediated disease characterized by inflammation and proliferation of the epidermis.

OBJECTIVES

Targeting intercellular adhesion molecule 1 (ICAM-1) is an attractive therapeutic option as this molecule is critically involved in leucocyte adhesion and extravasation as well as in lymphocyte activation.

METHODS

We have selected the fully human monoclonal antibody MOR102 (#5) against ICAM-1 from the Human Combinatorial Antibody Library (HuCAL). This antibody, as human IgG4 [corrected] was tested for its ability to interfere with lymphocyte activation and adhesion in vitro as well as for its antipsoriatic efficacy in vivo using the psoriasis-severe combined immunodeficient (SCID) mouse model.

RESULTS

The antibody demonstrated efficient inhibition of lymphocyte adhesion to ICAM-1 in vitro, with an IC(50) of approximately 0.4 microg mL(-1) (3 nmol L(-1)). In addition, MOR102 (#5) reduced lymphocyte proliferation in mixed lymphocyte cultures by approximately 50%. The in vivo efficacy of MOR102 (#5) was tested on grafts derived from lesional skin of patients with chronic plaque-stage psoriasis transplanted on to SCID mice. Intraperitoneal injection of 10 mg kg(-1) of MOR102 (#5) antibody every alternate day over a period of 4 weeks resulted in reconstitution of orthokeratotic differentiation and a significant (P < 0.05) reduction in epidermal thickness as well as marked reduction in the inflammatory infiltrate. Therapeutic activity may be related to the targeting of ICAM-1 on keratinocytes and thus preventing efficient activation of local T cells.

CONCLUSIONS

Based on the efficacy of the fully human monoclonal antibody MOR102 (#5) shown in vitro as well as in vivo in the psoriasis-SCID mouse model, initiation of clinical studies is indicated.

Presentation of ICAM-1 Protein at the Cell Surface of Oral Keratinocytes in the Presence of Adrenomedullin and Corticotrophin

Increasing evidence suggests that adrenomedullin (AM) and corticotrophin (ACTH) are immunomodulatory. Intercellular adhesion molecule-1 (ICAM-1) plays an important role in the recruitment of leukocytes not only from peripheral blood into inflamed tissues but also into epithelia. We have investigated the effects of AM and ACTH on the expression of ICAM-1 by human oral keratinocytes. The human oral keratinocyte cell line H357 was incubated with either AM or ACTH for up to 8 hrs and ICAM-1 expression was measured by cell surface ELISA. ICAM-1 was up regulated by both peptides and this was attenuated by the adenylyl cyclase inhibitor SQ22,536 and the NF-kappaB inhibitor SN-50. H357 cells constitutively express ICAM-1 mRNA and expression of this gene was significantly modulated by AM and ACTH. Furthermore AM caused translocation of NF-kappaB from the cytoplasm to the nucleus. This is the first report describing up regulation of ICAM-1 in oral keratinocytes by AM and ACTH and the results suggest both cAMP and NF-kappaB may play a role. These results further suggest both peptides may have an immunostimulatory role in oral muocsa and skin.

Lichen planus and leukocytoclastic vasculitis induced by interferon alpha-2b in a subject with HCV-related chronic active hepatitis

Lichen planus (LP) has been reported in association with chronic active hepatitis, primary biliary cirrhosis and other chronic liver diseases. The occurrence of LP in persons with hepatitis C virus (HCV) was reported by Robert et al., and the possible relationship between LP and hepatitis virus has also been supported by cases of LP following hepatitis B vaccination. Exacerbation or appearance of LP during the treatment of chronic hepatitis C, lymphoproliferative diseases and melanoma with alpha-interferon (IFN-alpha) and improvement of these diseases after discontinuation of this drug indicate that IFN-alpha may possibly induce LP. We present a case of cutaneo-mucous LP in a woman with chronic active hepatitis treated with IFN-alpha and in whom local leukocytoclastic vasculitis was induced by the intradermal injection of a very low dose of IFN-alpha.

Expression of the mucosal vascular addressin, MAdCAM-1, in inflammatory liver disease

AIMS/BACKGROUND

The integrin alpha4beta7 and mucosal addressin cell adhesion molecule-1 (MAdCAM-1) are involved in normal recirculation of lymphocytes between the blood and the tissues of the gastrointestinal tract. In this study we have examined the expression of MAdCAM-1 in human liver.

METHODS

MAdCAM-1 expression was determined in archival human liver tissues by immunohistochemistry.

RESULTS

While MAdCAM-1 was not detected in normal fetal or adult human liver, expression was observed in association with portal tract inflammation in a variety of liver diseases. Detailed analysis of liver biopsies from patients with hepatitis C showed a positive correlation between the portal/periportal component of the histological activity index (HAI) grade and the presence or absence of MAdCAM-1 expression.

CONCLUSION

MAdCAM-1 expression may be important in the recruitment of lymphocytes to the liver during inflammation.

Mechanisms of binding of cutaneous lymphocyte-associated antigen-positive and alphaebeta7-positive lymphocytes to oral and skin keratinocytes

Intraepithelial lymphocytes (IEL) utilize the integrin alphaebeta7 on their surface to bind to E-cadherin on epithelial cells in the gut and breast. In oral mucosa and skin IEL express alphaebeta7 and the cutaneous lymphocyte-associated antigen (CLA) but the mechanisms of adhesion of these subsets to keratinocytes are unknown. Levels of alphaebeta7 and CLA were up-regulated on peripheral blood lymphocytes (PBL) by transforming growth factor-beta (TGF-beta) and interleukin-12 (IL-12), respectively, and both groups of lymphocytes adhered onto oral and skin keratinocytes. Adhesion of IL-12-activated PBL was totally abolished by anti-lymphocyte-associated function antigen type 1 (anti-LFA-1) antibodies but was unaffected by anti-alphaebeta7 antibodies indicating that adhesion of the CLA-positive subset is mediated via LFA-1 interaction with intercellular adhesion molecule-1 (ICAM-1). Adhesion of TGF-beta-activated PBL to E-cadherin-positive oral and skin keratinocytes was partially inhibited by anti-alphaebeta7 antibodies but was unaffected by the blocking antibody E4.6 against E-cadherin which detects the binding site for alphaebeta7-positive lymphocytes in breast and gut epithelium. TGF-beta-activated PBL also bound to an E-cadherin-negative oral keratinocyte cell line and adhesion was inhibited by anti-alphaebeta7 antibodies. These results strongly suggest that in oral epithelium and epidermis alphaebeta7-positive lymphocytes do not bind to E-cadherin and there may be a novel second ligand for the alphaebeta7 integrin.

Human airway epithelial monolayers promote selective transmigration of memory T cells: a transepithelial model of lymphocyte migration into the airways

It has previously been demonstrated that T lymphocytes in the conducting airways express a pattern of adhesion molecules that are uniquely different from T lymphocytes found circulating in peripheral blood. To examine the role of airway epithelia in the determination of migratory capacity for human monocyte and lymphocyte populations in vivo, we have developed an in vitro transepithelial migration model using the human transformed bronchial epithelial cell line BEAS-2B S.6. In this study, we have demonstrated the preferential migration of human peripheral blood mononuclear cells (PBMC) across BEAS-2B S.6 cell monolayers in a physiologically appropriate direction (basal to apical epithelial cell surface). Stimulation of BEAS-2B S.6 cells with a combination of interferon-gamma and tumor necrosis factor-alpha upregulated basal-to-apical transepithelial migration by at least twofold. Monocytes migrated most efficiently, but subpopulations of CD19(+) B cells and CD2(+) cells were also recruited across epithelial cell monolayers. In the T lymphocyte subset of PBMC, CD45RO+ "memory" cells migrated preferentially. In addition, CD4(+) cells exhibited a significantly greater capacity to migrate across airway epithelium compared with CD8(+) cells. Migrated CD4(+) cells were predominantly CD29(high)/CD26(high), and within this subset uniformly expressed CD62L (L-selectin) at an intermediate level. PBMC migration across BEAS-2B S.6 cells was significantly inhibited by pertussis toxin; this result implicates a G protein signaling event as an important mediator of lymphocyte/monocyte transepithelial migration. On the basis of these data, we conclude that bronchial epithelium provides a unique microenvironment that supports the selective, G protein-dependent migration of memory T cells.

T lymphocytes from Sézary syndrome patients express beta1 integrins whose beta(1-6)-branched N-linked oligosaccharides reflect their adhesive capacity

Sézary syndrome (Sz), characterized by slowly progressing clonal proliferation of CD4+, CD45 RO+ T cells, has several forms that are distinguished according to the epidermotropic properties of the pathological cells. In a recent paper (Derappe C, Haentjens G, Lemaire S, Feugeas JP, Lebbe C, Pasqualetto V, Bussel A, Aubery M, Néel D. Leukemia 1996;10:138), we observed that T lymphocytes from most of the Sézary patients [Szbeta(1-6)+] expressed high levels of beta(1-6)-GlcNAc-branched N-linked oligosaccharides while T lymphocytes from other patients [Szbeta(1-6)-] did not. Because this observation suggests the possibility of two forms of Sz, distinguished according to the expression rate of these glycans, we looked for a possible relationship between this expression rate and T-cell adhesiveness. Using an original protocol (Braut-Boucher F, Pichon J, Rat P, Adolphe M, Aubery M, Font J. J Immunol Methods 1995;178:41), we observed that T lymphocytes obtained from the Szbeta(1-6)+ patients adhered less to normal keratinocyte monolayers than T lymphocytes from Szbeta(1-6)- patients and normal donors. As assessed by FACS analysis, all the integrin-subunits studied were more expressed on Szbeta(1-6)-, especially alpha4, alpha5, beta1 and beta2, than on Szbeta(1-6)+ and normal lymphocytes. Although these results suggest that beta1- and beta2-integrin expression is involved in the adhesive properties of these T-cells, other factors, such as glycosylation, may also contribute. To demonstrate this possibility, we sought the presence of beta(1-6)-GlcNAc-branched N-linked oligosaccharides on beta1 integrins expressed by T lymphocytes from Sz patients. Immunoblot experiments, performed using the specific lectin from Phaseolus vulgaris (Leukoagglutinin form), showed that only the beta1 integrin subunit expressed by T lymphocytes from Szbeta(1-6)+ patients carried these glycans, supporting the concept of the involvement of T-cell glycosylation in the evolution of Sz.

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.

Intra-epithelial subpopulations of T lymphocytes and Langerhans cells in oral lichen planus

This study has addressed the question of whether there is selective recruitment and distribution of intra-epithelial leucocytes in lesions of oral lichen planus (OLP). T-lymphocyte subsets were examined in the epithelium and peripheral blood of patients and controls using flow cytometry and double immunofluorescence, and the relationship between keratinocyte intercellular adhesion molecule-1 (ICAM-1) expression with T-lymphocyte and Langerhans cell (LC) distribution was examined. The circulating 'memory' subset (CD45RO+) of T-helper cells (CD4+) was increased from 49.1% in controls to 65.7% in patients (P=0.005), while the 'naive' subset (CD45RA+), which was absent from control epithelium, comprised 24% of helper cells in OLP (P=0.016). Fewer LC expressed CD45RO in OLP than in controls (P=0.037) and all T-cell and LC counts were significantly raised in ICAM-1-expressing areas of epithelium. These data demonstrate changes in intra-epithelial T-lymphocyte and LC populations compared with normal oral mucosa and suggest there is selective recruitment in OLP. In addition, keratinocyte ICAM-1 expression does appear to be associated with accumulation of infiltrating T lymphocytes and LC.

Immunohistology of skin and oral biopsies in graft-versus-host disease after bone marrow transplantation and cytokine therapy

BACKGROUND

Early diagnosis of graft-versus-host-disease (GVHD) after bone marrow transplantation is often difficult, particularly when the patients are immunosuppressed by chemotherapy or irradiation.

OBJECTIVE

To investigate the influence of cytokines on skin lesions after bone marrow transplantation.

METHODS

Biopsy specimens of skin and oral mucosa were obtained from bone marrow transplant patients with GVHD and were subjected to histologic and immunohistochemical examination.

RESULTS

Administration of granulocyte-macrophage colony-stimulating factor caused atopic dermatitis-like lesions in two patients, who had infiltration of neutrophils, eosinophils, and lymphocytes around the hair follicles of the skin and no signs of GVHD in other organs. Only patients who were treated with cytokines developed acute GVHD. Immunohistochemical examination of skin biopsies from 18 patients with acute GVHD and 11 patients with chronic GVHD after cyclophosphamide administration or irradiation showed that the maculopapular skin lesions characteristic of acute GVHD contained infiltrates of CD4+ and CD8+ lymphocytes. There was also an increase in numbers of epidermal keratinocytes expressing intercellular adhesion molecule-I and HLA-DR antigens.

CONCLUSION

These findings support the involvement of cytokines in GVHD and suggest that immunostaining of skin biopsies may be useful for the early diagnosis of this condition.

Erythroderma after autologous bone marrow transplantation modified by administration of cyclosporine and interferon gamma for breast cancer

BACKGROUND

Allogeneic graft-versus-host disease is associated with decreased rates of tumor relapse. The addition of interferon gamma to cyclosporine, given to induce graft-versus-host disease after autologous bone marrow transplantation, increases the extent of the cutaneous eruption.

OBJECTIVE

Our purpose was to describe the clinical and histologic cutaneous changes in 10 patients with breast cancer who received interferon gamma to potentiate graft-versus-host disease after autologous bone marrow transplantation modified by cyclosporine.

METHODS

Ten women receiving autologous bone marrow transplantation modified by the administration of cyclosporine and interferon gamma were observed clinically with sequential biopsy of the skin weekly and at the time of cutaneous eruptions.

RESULTS

Erythroderma (stage 3) developed in five women after the first or second administration of interferon gamma. At least on skin biopsy specimen from 7 of the 10 women showed grade 2 changes of graft-versus-host reaction, including all patients with erythroderma. Epidermal intercellular edema was prominent in these specimens with expression of keratinocyte HLA-DR and intercellular adhesion molecule 1. Induction of keratinocyte HLA-DR and intercellular adhesion molecule 1 expression was not observed in specimens from normal skin during administration of interferon gamma.

CONCLUSION

This protocol causes a more widely distributed cutaneous eruption, including erythroderma (50%), than autologous bone marrow transplantation and cyclosporine administration alone (3%). Whether it will affect survival is unknown.

Synovial cells are potent antigen-presenting cells for superantigen, staphylococcal enterotoxin B (SEB)

There is ample evidence suggesting that superantigens may act as a triggering factor in the pathogenesis of rheumatoid arthritis (RA). We investigated whether superantigen could activate T cells in the presence of synovial cells. T cells were cultured with SEB in the presence of interferon-gamma (IFN-gamma)-treated synovial cells. T cell proliferation and activation were assessed by 3H-thymidine incorporation and IL-2 production. The expression of HLA class II antigens and adhesion molecules on synovial cells was detected by flow cytometer. In the presence of IFN-gamma-treated synovial cells, T cells proliferated vigorously and produced IL-2 in response to SEB. A low SEB-induced T cell response was noticed in the presence of untreated synovial cells. Allogeneic as well as autologous IFN-gamma-treated synovial cells markedly enhanced SEB-induced T cell proliferation. IFN-gamma-treated synovial cells had increased expression of HLA class II antigens and intercellular adhesion molecule-1 (ICAM-1) adhesion molecules. MoAbs towards these antigens markedly inhibited the SEB-induced T cell response. These results indicate that activated synovial cells are potent antigen-presenting cells for SEB to T cells, and that superantigens may play a critical role in the pathogenesis of RA through activated synovial cells.

Specific lymphocytotoxic destruction of autologous epithelial cell targets in recurrent aphthous stomatitis

Concepts of the immunopathogenesis of recurrent aphthous stomatitis (RAS) based on lesion histology suggest an early role for CD4+ T cells. Other in vitro studies show enhanced destruction of epithelial targets by peripheral blood mononuclear cells (PBMC) from RAS subjects. The present project aimed to extend these studies under conditions simulating the in vivo situation. Epithelial cells were cultured and induced to express class I and class II major histocompatibility complex (MHC) antigens with gamma interferon (gamma-IFN). Co-cultures with autologous PBMC showed evidence of specific destruction of epithelial targets in RAS patients when compared with a control group. Co-culture with CD4+ enriched cells also showed specific epithelial cell lysis. Effector cells pre-incubated with interleukin-2 (IL-2) did not produce increased destruction of epithelial cells. This study has supported previous work and identified an early role of CD4+ cells.

Induction of intercellular adhesion molecule-1 and adherence of HTLV-1-infected T-cells to cultured keratinocytes

Cutaneous lesions of T-cell proliferative disorders are characterized by epidermotropic infiltration of the neoplastic cells and expression of intercellular adhesion molecule-1 (ICAM-1) and HLA-DR by lesional keratinocytes. Using cloned HTLV-1-infected T-cells obtained from patients with adult T-cell leukemia (ATL), we have studied immunobiological activities of cytokines released from the T-cell lines and their ability to adhere to cultured keratinocytes. Three out of the five CD-4-positive, HTLV-1-infected T-cell clones secreted both IFN-gamma and IL-4, similar to murine Th0 clones. The other two clones did not produce such cytokines. ICAM-1 and HLA-DR molecules were induced on cultured normal human keratinocytes and organ-cultured skin specimens by co-cultivation with IFN-gamma-producing T-cell clones or their culture supernatants. Induction of both molecules was markedly inhibited by pretreatment of the supernatants with excess amounts of anti-IFN-gamma monoclonal antibody. The number of cells adherent to the normal cultured keratinocytes was greater in the IFN-gamma-producing clones than in the non-producing ones. These data suggest that some HTLV-1-infected clones produce cytokines, including IFN-gamma, which in turn induce ICAM-1 on keratinocytes, thereby enhancing the ability of the T-cell clones to adhere to the keratinocytes.

Corticosteroids induce proliferation but do not influence TNF- or IL-1 beta-induced ICAM-1 expression of human dermal microvascular endothelial cells in vitro

The effects of hydrocortisone, dexamethasone, betamethasone 17-valerate and clobetasol propionate at concentrations of 10(-5)-10(-12) M on the proliferation of human dermal microvascular endothelial cells (HDMEC) were studied in vitro. In addition, confluent HDMEC were treated with TNF (1000 U/ml) or IL-1 beta (1000 U/ml) alone or in combination with the corticosteroids (10(-5) M, 10(-6) M) for 24 h, and cytokine-induced expression of intercellular adhesion molecule-1 (ICAM-1) was assessed by immunocytochemistry. Controls were treated either with growth medium or with the corticosteroids alone. All tested corticosteroids stimulated HDMEC growth after 4 and 6 days of treatment in a dose-dependent manner, as assessed by 3H-thymidine incorporation and the 4-methyl-umbelliferyl heptanoate (MUH) assay. The minimal effective concentration was 10(-9) M for hydrocortisone, 10(-10) M for dexamethasone and betamethasone, and 10(-12) M for clobetasol. In untreated and in corticosteroid-treated cultures, less than 5% of the cells expressed ICAM-1. TNF and IL-1 beta were strong inducers of ICAM-1 expression on 74% and 82% of the cells, respectively. None of the tested corticosteroids significantly influenced cytokine-induced ICAM-1 expression, suggesting that the anti-inflammatory effects of corticosteroids are not related to ICAM-1 modulation on HDMEC.

Response of aged versus young skin to intradermal administration of interferon gamma

BACKGROUND

Interferon gamma (IFN-gamma) induces the interaction of intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen type 1 expression, and of HLA-DR antigens by keratinocytes.

OBJECTIVE

The aim of the present study was to determine the potential ability of aged versus young skin to respond to intradermal administration of IFN-gamma, as an in vivo immunologic stimulus.

METHODS

For 3 consecutive days elderly and young volunteers were injected with 10 micrograms of recombinant IFN-gamma diluted in 0.1 ml of sterile water. On day 5, punch biopsy specimens were obtained from the injected sites. Histologic and immunohistochemical stainings were performed on all sections.

RESULTS

ICAM-1 was expressed by keratinocytes in both aged and young skin. An impairment was manifested mainly by the reduced accumulation of mononuclear cells throughout the dermis, the absence of HLA-DR expression by keratinocytes in 7 of 10 elderly volunteers, and the absence of an effect on the Langerhans cell population.

CONCLUSION

This observation shows a diminished immune response in aged skin.

Preferential adherence of T lymphocytes and neutrophils to psoriatic epidermis

T lymphocytes and neutrophils accumulate in psoriatic epidermis. To determine whether the epidermis plays an active role in this process through the production of cellular adhesion factors, leucocyte adherence to lesional psoriasis was compared with normal skin in a modified frozen-section adhesion assay. Lymphocyte and neutrophil suspensions were prepared by standard Ficoll-Hypaque techniques from peripheral blood of normal volunteers and overlaid on to glutaraldehyde-fixed 8-microns cryostat sections of skin. Adhesion of phorbol ester-activated T lymphocytes to the epidermis was significantly greater in psoriasis compared with normal skin (P < 0.01). Adhesion was absent (a) at 7 degrees C, (b) in the presence of EDTA and (c) in the absence of lymphocyte activation. Immunostaining demonstrated that all adherent lymphocytes were CD3+ve (i.e. T cells). Likewise, neutrophils adhered more prominently to psoriatic epidermis. Adhesion was most prominent at the tips of dermal papillae, corresponding to areas of maximal intercellular adhesion molecule-1 (ICAM-1) expression. Both neutrophils and lymphocytes adhered to dermal papillary vascular endothelium. These studies provide functional data that psoriatic epidermal cells are actively involved in leucocyte adherence. The distribution of adhesion suggests that both ICAM-1-dependent and independent mechanisms are involved.

Dynamics of the cellular and humoral components of the inflammatory response elicited in skin blisters in humans

Skin blisters induced by suction on the forearm of normal volunteers provide a convenient model to study the inflammatory response in vivo in man. In our study, after removal of the roof of the blister, i.e., the epidermis, the exposed floor of the blister (dermal-epidermal interface) was bathed with 70% autologous serum using a multiwell skin chamber. Migration of leukocytes (90-95% neutrophils) into the chamber fluid was detectable within 3 h, and appeared to plateau at 16-24 h. Sampling of the dermal-epidermal interface revealed primarily mononuclear cells during the first 8 h of the inflammatory response; however, their prevalence at 24 h was greatly diminished due to neutrophil infiltration. Accompanying the cellular immune response was the accumulation of inflammatory mediators in the bathing medium. The accumulation of IFN-gamma reached a plateau within 3 h; significant accumulations of the complement fragment, C5a, and of leukotriene B4 were also detected at 3 h. The accumulation of C5a did not peak until 5 h, whereas leukotriene B4 continued to accumulate through 24 h. IL-6 and IL-8 concentrations were minimal at 3-8 h but dramatic by 24 h while IL-1 beta, tumor necrosis factor-alpha, and granulocyte-macrophage colony-stimulating factor were undetectable within 3-8 h, but markedly elevated by 24 h. There was little accumulation of IL-4 and no accumulation of IL-1 alpha or IL-2 during the 24-h period. The sequential appearance of mediators at an inflammatory focus suggests that a carefully regulated dynamic system is responsible for controlling the evolution of the inflammatory response.

Cytokine regulation of proliferation and ICAM-1 expression of human dermal microvascular endothelial cells in vitro

The effects of recombinant human interleukin 1 alpha (IL-1 alpha), interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6), granulocyte/macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor-alpha (TNF) on the cell proliferation and the expression of intercellular adhesion molecule-1 (ICAM-1) were assessed in cultured human dermal microvascular endothelial cells (HDMEC). IL-1 alpha and IL-1 beta stimulated the proliferation of HDMEC in a dose-dependent manner, whereas in control experiments using human umbilical vein endothelial cells (HUVEC), IL-1 alpha and IL-1 beta did not stimulate HUVEC growth. Also GM-CSF stimulated the proliferation of HDMEC, whereas IL-6 did not affect endothelial cell growth in vitro. Treatment with IL-1 alpha, IL-1 beta, and TNF markedly increased the expression of ICAM-1 on HDMEC in a time- and dose-dependent manner, in contrast to IL-6 and GM-CSF. By pre-embedding immunoelectron microscopy, membrane-bound expression of ICAM-1 was visualized with pronounced labeling in areas of microvillous cell protrusions. The TNF-induced expression of ICAM-1 on HDMEC was blocked by co-incubation with a neutralizing antibody against TNF, but not with neutralizing antibodies against IL-1 alpha, IL-1 beta, or IL-6. In addition, co-incubation of HDMEC with TNF and the retinoid compound acitretin, dexamethasone, or indomethacin did not abrogate the TNF-induced ICAM-1 expression. These results disclose IL-1 as a major, multifunctional endothelial cell-targeted cytokine and further confirm the concept that pro-inflammatory cytokines exert differential regulatory effects on dermal microvascular endothelial cell proliferation and expression of cell-adhesion molecules.

Epidermal keratinocytes of bullous pemphigoid express intercellular adhesion molecule-1 (ICAM-1)

Intercellular adhesion molecule-1 (ICAM-1) is the ligand for lymphocyte function associated antigen-1 (LFA-1), mediating the adhesion of lymphocytes to vascular endothelium. Keratinocytes are known to express ICAM-1 in some inflammatory dermatoses. Using an indirect immunofluorescence method, we examined the patterns of ICAM-1 and LFA-1 staining in bullous pemphigoid (BP) lesions and compared them to pemphigus vulgaris (PV) cases. ICAM-1 was expressed on the cell surface and in the cytoplasm of epidermal keratinocytes at the sites of erythematous and bullous lesions of BP. LFA-1 molecules were expressed on T cells at the basement membrane zone. In addition, HLA-DR-positive keratinocytes were observed in the basal layer. ICAM-1 was not, however, expressed on epidermal keratinocytes in uninvolved skin from BP patients, PV or normal control skin. It is known that ICAM-1 is expressed on keratinocytes at the site of lymphoid infiltration in cutaneous dermatoses and that LFA-1-positive T cells can bind to interferon gamma-induced ICAM-1-positive keratinocytes. Our results suggest that cellular immunity involving ICAM-1 and LFA-1 may play a part in the pathogenesis of bullous pemphigoid.

Autocrine stimulation of interleukin-1 alpha and transforming growth factor alpha production in human keratinocytes and its antagonism by glucocorticoids

Interleukin-1 (IL-1) and transforming growth factor alpha (TGF alpha) mRNA expression was analyzed in cultured normal human keratinocytes. Keratinocytes constititively express IL-1 mRNA when cultured in keratinocyte growth medium but not in Dulbecco's minimal essential medium containing fetal bovine serum, in which the cells differentiate. The predominant form of IL-1 expressed by keratinocytes is IL-1 alpha. Addition of IL-1 alpha to keratinocytes increased IL-1 alpha and TGF alpha mRNA expression in a dose-dependent manner. TGF alpha induced a similar increase in IL-1 alpha and TGF alpha mRNA in keratinocytes. Hydrocortisone decreased the expression of both IL-1 alpha and TGF alpha mRNA in keratinocytes. These findings document an autocrine mechanism by which IL-1 alpha and TGF alpha can stimulate the proliferation of keratinocytes in the skin. It is proposed that this autocrine loop may be hyperactive in psoriasis. Antagonism of the effects of this autocrine loop may be one of the mechanisms by which glucocorticoids exert clinically useful effects in psoriasis and other diseases of the skin.

Effects of rIFN alpha, beta, and gamma on the morphology, proliferation, and cell surface antigen expression of human dermal microvascular endothelial cells in vitro

The influence of recombinant human interferon alpha 2a (rIFN alpha), recombinant human interferon beta 1 (rIFN beta), and recombinant human interferon gamma (rIFN gamma) on human dermal microvascular endothelial cells (HDMEC) cultured in vitro was studied in various rIFN concentrations (0.1 IU/ml-10(4) IU/ml) over 2, 3, 4, 6, 8, and 10 d. Cell morphology and ultrastructure, cell proliferation, expression of class II alloantigens (HLA-DR and HLA-DQ), and intercellular adhesion molecule-1 (ICAM-1) were investigated using an in vitro technique established in our laboratory. All rIFN tested induced alterations of typical HDMEC morphology; the cells became spindle-shaped and fibroblastoid, although they maintained their endothelial cell marker expression. Also, all IFN dose- and time-dependently inhibited the proliferation of HDMEC in vitro (rIFN alpha greater than beta greater than gamma), whereby rIFN alpha exerted the strongest growth-inhibitory effect. Alkaline phosphatase anti-alkaline phosphatase (APAAP) immunocytochemistry of the cultured cells showed dose- and time-dependent stimulation of ICAM-1 and class II antigen expression only by rIFN gamma (HLA-DR greater than HLA-DQ), rIFN alpha and beta did not exert any immunomodulatory activity on HDMEC in vitro. These results indicate that HDMEC are an important target for the action of IFN. Besides growth inhibition, it seems that rIFN gamma in particular may be involved in the modulation of leucocyte adhesion and trafficking by altering the immunophenotype of the endothelial cell population.

Interferons and collagen production

The immunoregulatory, antiviral, and antiproliferative agents known as the interferons have profound effects on collagen synthesis. Interferons alpha, beta, and gamma suppress collagen synthesis by dermal fibroblasts. In addition, interferon gamma (IFN-gamma) inhibits the constitutively increased collagen synthesis characteristic of fibroblasts derived from lesions of patients with scleroderma. IFN-gamma also inhibits collagen synthesis by myofibroblasts and synovial fibroblast-like cells. Inhibition of collagen synthesis by IFN-gamma is associated with a coordinate inhibition of transcription for types I and III collagen. In addition, IFN-gamma suppresses levels of procollagen mRNA and type II collagen synthesis in human articular chondrocytes. In vivo studies in mice have demonstrated that IFN-gamma inhibits the collagen synthesis associated with the fibrotic response to an implanted foreign body, bleomycin-induced pulmonary fibrosis, and the healing response to cutaneous thermal burns. In the latter case, while collagen content of the wound scar was decreased, hyaluronic acid was increased in mice receiving IFN-gamma compared to controls. This is in accord with in vitro studies showing that, while interferons alpha and beta decrease production of glycosaminoglycans, IFN-gamma increases production of glycosaminoglycans. Of interest, acute inflammation at sites of thermal injury, or when elicited by proinflammatory agents in separate experiments, also was suppressed in mice treated with IFN-gamma. The means by which IFN-gamma inhibits collagen synthesis involves transcriptional regulation. There is a single report that interferon alpha can decrease the size of a keloid of recent onset in a human patient. Because the interferons can inhibit collagen synthesis in vivo, further studies may be warranted to evaluate the usefulness of these agents in the treatment of disease states characterized by abnormal fibrotic responses as well as their potential for altering the healing response associated with particular therapeutic interventions.

Regulation of 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE) binding sites on human epidermal cells by interferon-gamma

We recently detected specific high-affinity binding sites for 12(S)-HETE, the main arachidonic acid metabolite in skin, on epidermal cells. The putative receptor is involved in keratinocyte chemotaxis toward 12(S)-HETE, which points to its participation in wound healing. In an effort to further characterize the 12(S)-HETE receptor, we investigated its regulation by various cytokines. Of the tested cytokines, only interferon (IFN)-gamma led to a massive induction of the 12(S)-HETE receptors. The effect was dose and time dependent and blocked by cycloheximide. The up-regulation of 12(S)-HETE receptors by IFN-gamma may represent an amplification mechanism of the assumed role of 12(S)-HETE in skin wound repair.

Effects of recombinant tumor necrosis factor-alpha on cultured microvascular endothelial cells derived from human dermis

We investigated the effects of recombinant human tumor necrosis factor-alpha (TNF) on cell proliferation and on expression of MHC class II antigens and intercellular adhesion molecule ICAM-1 in human dermal microvascular endothelial cells (HDMEC) derived from human foreskin. Second-passage HDMEC were treated with 0.1-10,000 U/ml TNF for up to 6 d, and cell growth was assessed by cell counts and a recently developed fluorogenic assay using 4-methylumbelliferyl heptanoate as a substrate. APAAP immunocytochemistry was performed using monoclonal antibodies against HLA-DR, HLA-DQ, and ICAM-1. TNF did not markedly inhibit the growth of HDMEC but induced expression of HLA-DR (1,000 U/ml and more) and of ICAM-1 (1 U/ml and more). Combination with interferon-gamma led to synergistic ICAM-1 induction. These results demonstrate a profound effect of TNF on the activation of dermal microvascular endothelial cells and suggest a major role of TNF in the mediation of leucocyte adhesion to endothelial cells of the skin microvasculature with possible implications for the initiation and maintenance of inflammatory skin processes.

Interactions between lymphocytes and dermal fibroblasts: an in vitro model of cutaneous lymphocyte trafficking

Cultures of dermal fibroblasts were established from skin biopsies of CBA mice and used to study the interactions with murine T-lymphocytes. Electron microscopy showed that zones of contact developed between the fibroblasts and the T-cells, particularly after mitogenic activation. The adhesion of the lymphocytes was temperature-dependent, and many more lymphoblasts than resting cells attached to the fibroblast monolayers. Flow cytometry analysis of the adherent population showed that the most prominent type of resting lymphocyte was of the CD4 phenotype, which was also observed using a T-helper lymphoid cell line. However, neither the CD4 nor the CD8 (T-cytotoxic) antigens were involved in the binding process, and while the fibroblasts expressed Class I MHC molecules (but not Class II), these also had no role in mediating lymphocyte adhesion. Although the fibroblasts did not express the ligand Mala-2, the murine homologue of human ICAM-1, a monoclonal antibody against LFA-1, its cognate receptor on the lymphocytes, nevertheless effectively inhibited binding. T-cell attachment was also partially prevented by antibody against the lymphocyte CD2 antigen and by RGDS, a protein epitope known to mediate a number of receptor-integrin interactions. Moreover, this peptide also rapidly and preferentially detached T-lymphocytes which had previously adhered to the fibroblast monolayers. Lymphocyte binding was substantially elevated following treatment of the fibroblasts with cytokines such as tumor necrosis factor-alpha and interferon-gamma, but not interleukin-1 alpha. This increase in adhesiveness was, however, almost completely abolished by monoclonal antibodies specific for LFA-1 or for Mala-2. The results of this study show that while lymphocytes recognize fibroblasts normally via a number of constitutively expressed receptor-integrin interactions, their adhesion can also be modulated by cytokine-induced changes in the expression of other surface ligands.

Spectophotometric quantification of cell-cell adherence by an enzyme-linked immuno-cell adhesion assay

In the present study a spectophotometric method was developed to determine the number of T cells binding to human epidermal keratinocytes (KC). In this cell adhesion assay the adherent T cells were detected with a cell-specific monoclonal antibody conjugated to horseradish peroxidase and the coloured substrate quantified in an ELISA reader at 492 nm. A correlation was demonstrated between the number of T cells and the extinction values measured. The enzyme-linked immuno-cell adhesion assay (ELICAA) was used to quantify KC/T lymphocyte adherence in a series of experiments designed to evaluate its reliability and reproducibility. Compared with the 51Cr-labelled adherence assay, the ELICAA was a safe, rapid and accurate method avoiding the use of radioactive material.

The role of adhesion molecules, chemotactic factors, and cytokines in inflammatory and neoplastic skin disease--1990 update

In 1986 it was discovered that cultured human keratinocytes, when treated with gamma interferon, attract and bind T lymphocytes and monocytes. More is now known about trafficking of inflammatory cells in the skin, with specific molecular details involving various cytokines, chemotactic factors, and adhesion molecules. One key element is the in vivo movement of T cells that express LFA-1 into the epidermis, and their subsequent binding to keratinocytes via the surface expression of intercellular adhesion molecule-1 (ICAM-1). This interaction represents a common immunologic pathway, which has been identified in a wide variety of different skin diseases. This review provides a synopsis of advances in this field, which have grown rapidly during the past few years, and adds recent results dealing with coordinate regulation at the gene-transcriptional level of keratinocyte chemotactic factor production and adhesion molecule expression. Moreover, epidermal keratinocytes appear to play a pre-eminent role in the skin, serving as transducing elements converting exogenously applied low-molecular-weight chemical stimuli such as phorbol ester and urushiol (the active ingredient in poison ivy extracts) into the production of endogenously derived immunoregulatory proteins. These keratinocyte-derived molecules may then influence immunocytes and endothelial cells to further amplify the inflammatory response. The identification of keratinocyte-derived molecules such as IL-8 and ICAM-1, which influence the chemotaxis and adherence of T cells, adds substantial evidence supporting an active participatory role for keratinocytes in cutaneous immunohomeostasis. Finally, we highlight the importance of these immunoregulatory molecules in two malignant cutaneous disorders (cutaneous T-cell lymphoma and basal-cell carcinoma) and attempt to integrate these new findings into novel pathophysiologic models for two inflammatory dermatoses (rhus dermatitis and psoriasis).

Tumor necrosis factor-alpha inhibits cell proliferation and induces class II antigens and cell adhesion molecules in cultured normal human keratinocytes in vitro

The effects of recombinant human tumor necrosis factor-alpha (TNF) on cell proliferation, cell morphology, and on the expression of class II alloantigens and intercellular adhesion molecule-1 (ICAM-1) were assessed in human keratinocytes cultured in serum-free medium. TNF inhibited cell proliferation in a time- and dose-dependent manner with a minimum effective dose of 10 U/ml and a 50% inhibitory dose of 100 U/ml. However, TNF did not induce cell death, and the growth inhibition induced by TNF was completely reversible after its withdrawal. In vitro combination of TNF with interferon-alpha (IFN-alpha) and IFN-beta resulted in additive growth inhibitory effects, while IFN-gamma enhanced the TNF mediated growth inhibition in a synergistic way. Furthermore, TNF altered the morphology of the growing keratinocytes inducing the appearance of a fusiform, fibroblast-like population. Also, treatment with TNF over 6 days markedly induced the expression of ICAM-1 on the cultured keratinocytes with a minimal effective dose of 10 U/ml, while HLA-DR was only moderately expressed after 1,000 U/ml. TNF did not induce HLA-DQ, but reduced the IFN-gamma induced expression of HLA-DR and HLA-DQ. By immunoelectron microscopy, an intense membrane-bound labeling for ICAM-1 was found after treatment with TNF, clearly pronounced in areas of microvillous membrane protrusions. These results indicate that epidermal keratinocytes are a major target for various biological effects of TNF. We also found that TNF differentially modulates IFN-gamma-induced effects, thus suggesting its potential role in the regulation of inflammatory skin disorders.

The activated keratinocyte: a model for inducible cytokine production by non-bone marrow-derived cells in cutaneous inflammatory and immune responses

Keratinocytes, fibroblasts, endothelial cells, and other sessile cells resident to human skin can be induced in vitro to synthesize and secrete cytokine molecules. Cytokines are small protein molecules produced upon injury or cellular activation which influence immune and inflammatory events; as such, they have been best understood previously as products of leukocytes. The appreciation that cultured non-bone marrow-derived cells from skin could produce cytokines capable of initiating an inflammatory response or facilitating an immune response has led to speculation that cells resident to skin may be less passive participants in such phenomena than previously thought. Using as a model the cultured keratinocyte, which produces both interleukin-1 alpha and beta and an interleukin-1 receptor, models of autocrine and paracrine activation of this cell have been constructed. Such "activated keratinocytes," or by analogy other activated resident skin cells, produce a spectrum of cytokines in vitro which could potentially influence leukocyte adhesion to endothelium, direction migration of leukocytes towards the activated cell (presumably an inflammatory nidus), and activation of leukocyte functions in situ. The putative role of regulation of cytokine and cytokine-receptor regulation in mediating the activation of such cells (and thus, presumably, local inflammation) is discussed. An important aspect of this hypothetical model is that in the absence of activation (which characterizes normal uninflamed skin), cytokine production and its consequences do not occur. The conclusion reached is that based on in vitro data it is plausible to guess that local inflammatory or immune responses can be both initiated and facilitated by locally produced cytokines.

Differential modulation of keratinocyte intercellular adhesion molecule-I expression by gamma interferon and phorbol ester: evidence for involvement of protein kinase C signal transduction

There is growing evidence that keratinocyte (KC) intercellular adhesion molecule-I (ICAM-I) expression is involved in the epidermal trafficking of T lymphocytes. To further characterize the molecular basis of KC ICAM-I expression, the detailed kinetics of induction by gamma interferon (IFN-gamma), as well as the phorbol ester, 12-O tetradecanoylphorbol-13-acetate (TPA), were studied. This study reports that KCs express both the class II major histocompatibility antigen (HLA-DR) and ICAM-I in response to IFN-gamma, although the response is distinctive for each molecule. Also, TPA induces ICAM-I, but not HLA-DR expression, whilst the protein kinase inhibitor, H7, blocks the TPA, but not the IFN-gamma-mediated response. The results provide a molecular basis whereby non-cytokine-mediated stimuli (e.g. TPA) alter KC signal transduction events involving protein kinase-C (PK-C) and thereby generate such immunologically relevant events as ICAM-I expression. Thus, KCs may be targets for both T-cell derived cytokines (e.g. IFN-gamma), and non-cytokine TPA-like molecules which stimulate PK-C. Induction of ICAM-I by either mechanism would be capable of instigating intraepidermal T-cell trafficking.

Differential expression of lymphocyte function-associated antigen 1 (LFA-1) on epidermotropic and non-epidermotropic T-cell clones

Various T-cell surface molecules are involved in T-cell adhesion, which is an essential requirement for epidermotropic migration of T cells. Our previous studies demonstrated that certain T-cell clones can migrate into the epidermis upon their intradermal inoculation into the footpads of recipient mice with relevant antigens, while other T-cell clones, despite their identical antigen specificities and functions, are non-epidermotropic. We therefore tested whether the differences in epidermotropism of these T cells could reside in the different levels of expression of T-cell surface molecules such as CD3, CD4, CD2, and lymphocyte function associated antigen 1 (LFA 1). The results of flow cytometric analysis showed that LFA-1 was preferentially expressed on the surface of epidermotropic T-cell clones, while non-epidermotropic T-cell clones were negative or very weakly positive for LFA-1 with one exception. After exposure to phorbol ester, epidermotropic clones with high levels of LFA-1 did not show any further up-regulation of LFA-1. In contrast, under identical conditions, significant up-regulation of LFA-1 was observed on non-epidermotropic T cells with low levels of LFA-1. However, even after exposure to phorbol ester, these T cells remained non-epidermotropic. These results suggest that the presence of high levels of LFA-1 on T cells is absolutely necessary for their epidermotropic migration, but its up-regulation is neither necessary nor sufficient to trigger the epidermotropic migration. High levels of LFA-1, regardless of cell activation, may be required to mediate stable cell adhesions leading to epidermotropic migration.

Human epidermal basal keratinocytes express CDw29 antigens

Two monoclonal antibodies, K20 and 4B4, assigned to the CDw29 cluster of differentiation antigens, were shown to react with basal keratinocytes (BK). The aim of this study was to identify the antigens recognized by K20 and 4B4 on epidermal cells, and to determine whether they were identical to those found on lymphocytes. Basal keratinocyte-enriched cell suspensions were labelled with 125I and then 1% NP40 cell lysates were used for immunoprecipitation. Under reducing conditions, K20 and 4B4 immunoprecipitated from basal keratinocytes a broad MW 105,000 band and proteins of MW 145,000, 90,000 and 80,000. Under non-reducing conditions, each band was shifted down by approximately 5000 MW. Metabolic labelling studies demonstrated that the MW 145,000 and 105,000 subunits were synthesized by basal keratinocytes. On lymphoid cells, K20 and 4B4 are known to precipitate glycoprotein complexes made of a broad MW 130,000 protein band (beta subunit) associated with a protein of MW 150,000 (alpha subunit) and proteins of MW 90,000 and 80,000 expressed in very low amounts. The MW 145,000 and 105,000 bands immunoprecipitated by K20 from basal keratinocytes correspond to the alpha and beta subunits present on lymphoid cells. It has recently been demonstrated that K20 recognizes the common beta subunit of the very late antigens family (VLA) and that 4B4 defines the helper-inducer subset of T lymphocytes. The present investigation provides evidence that basal keratinocytes share antigens of the VLA family with lymphoid cells and that they play an important role in the immune response in the skin-immune system.

The effect of in vivo interferon-gamma on the distribution of LFA-1 and ICAM-1 in normal human skin

Lymphocyte function associated antigen 1 (LFA-1) and its ligand intercellular adhesion molecule 1 (ICAM-1) are cell surface adhesion molecules important in many lymphocyte-mediated responses. Recent in vitro studies have demonstrated that the cytokine interferon-gamma (IFN-gamma) can induce ICAM-1 expression by keratinocytes, and that lymphocytes adhere to IFN-gamma treated keratinocytes. In view of the importance of keratinocyte/lymphocyte interactions in the pathogenesis of cutaneous disease, we have examined the effects of in vivo IFN-gamma on cutaneous expression of LFA-1 and ICAM-1. Fourteen volunteers received intradermal IFN-gamma (dose: 1 or 10 micrograms) daily for 3 d. Biopsy was obtained on day 6. Cryostat sections were stained by the peroxidase antiperoxidase technique employing murine monoclonal antibodies to CD11, CD18, and ICAM-1. IFN-gamma intensified ICAM-1 expression by dermal endothelial cells and induced keratinocyte expression of ICAM-1. Furthermore, after administration of 10 micrograms of IFN-gamma LFA-1 positive (LFA + ve) lymphocytes were observed along the basement membrane zone closely related to ICAM-1 + ve basal keratinocytes and also surrounding dermal endothelium. Exposure to IFN-gamma induced expression of both CD11a and CD18 antigens on epidermal Langerhans cells. These studies suggest that the distribution of adherence molecules expression within cutaneous tissue in vivo is modulated by IFN-gamma, and that these alterations may be important in interactions involving cutaneous immunocompetent cells.

Decreased growth inhibition by recombinant gamma interferon is associated with increased transforming growth factor-alpha production in keratinocytes cultured from psoriatic lesions

Keratinocytes from involved psoriatic plaques (PP), uninvolved, clinically symptomless skin of psoriatic patients (PN) and normal healthy skin (NN) have been cultured in a low calcium serum free system for multiple passages. In this way, the keratinocytes were removed from microenvironmental factors present in the skin. While the basal rate of proliferation of the PP, PN and NN keratinocytes was not different, the PP cells produced more transforming growth factor-alpha (TGF-alpha) than NN cells, and the antiproliferative response of PP cells to gamma interferon (IFN-gamma), a product of activated T lymphocytes, was reduced. We studied IFN-gamma because it can inhibit the proliferation of NN keratinocytes, induce their differentiation and the appearance of two immunoregulatory cell surface molecules, HLA-DR and intercellular adherence molecule-I (ICAM-I), and because in another epithelial cell system, epidermal growth factor (EGF) modulates IFN-gamma activity. The mean antiproliferative effects of IFN-gamma at 50,200, and 500 U/ml for the PP group (n = 10) was less compared to the NN group (n = 11); P less than 0.001, while the PN group (n = 5) had a less dramatic, but statistically significant, reduction in growth inhibition by IFN-gamma only at 200 and 500 U/ml compared to NN cells; P less than 0.05 and P less than 0.01, respectively. The amount of TGF-alpha produced and secreted by PP keratinocytes from five different individuals was significantly greater than by NN keratinocyte cultures. In addition, IFN-gamma induced TGF-alpha to a lesser extent in PP keratinocytes compared to NN keratinocyte cultures. Keratinocytes isolated from atopic dermatitis and Sézary syndrome patients were similar to NN keratinocytes. In contrast to its differential effects on TGF-alpha production and proliferation, IFN-gamma induced similar amounts of HLA-DR and ICAM-I on PP, PN and NN keratinocytes. Thus, for the PP keratinocytes, there was a dissociation between the antiproliferative and immunomodulatory effects of IFN-gamma. These results support our previous hypothesis that the hyperproliferation and altered differentiation of keratinocytes in psoriatic plaques is linked to an altered responsiveness of the keratinocytes to IFN-gamma. Moreover, these results provide an in vitro correlate of our in vivo observation of increased TGF-alpha levels in psoriatic plaques. A new pathophysiological model to understand psoriasis is proposed which integrates these observations involving IFN-gamma and TGF-alpha. This experimental approach also provides a system to dissect biochemical pathways of pathophysiological importance for keratinocyte hyperproliferation in psoriasis.

Adhesion of lymphoid cells to fibroblasts in tissue culture

In this study we have examined the cellular and molecular specificity of lymphocyte interaction with fibroblasts. Using mitogen-activated T-cells, we found that attachment to fibroblasts was highly sensitive to protease treatment, and to an antibody raised against the purified lymphocyte plasma membrane, but it was not mediated by the MEL-14 surface antigen or phosphomannosyl receptors. Lymphocyte interaction with fibroblasts was also unaffected by monoclonal antibodies against the LFA-1, Mac-1, and Class II MHC antigen complexes. In contrast, adhesion of both T- and B-lymphocytes was strongly inhibited by fucoidan, a polymer of sulphated fucose, whereas fucose, mannan, and mannose 6-phosphate had no effect. Both B- and T-lymphoid cell lines were able to recognise and adhere to fibroblasts, although the marked differences between the attachment of the different types of cell did not appear to be related to their immunological function. The attachment of most of the cell lines was prevented by the presence of fucoidan, whereas the inhibition of binding of each of the lymphoid lines in the presence of the anti-T-lymphocyte plasma membrane antibody varied widely. These findings suggest that lymphocyte attachment to fibroblasts involves multiple cell surface receptors, and that these are expressed at different levels on specific T- and B-cells.

Interferon-gamma as adjuvant therapy for resistant warts

A patient who for 26 years had common warts, which were resistant to various treatment modalities, was treated with a single intralesional injection of interferon-gamma after dinitrochlorobenzene immunotherapy, because immunologic studies indicated she had failed to respond to prior treatment modalities as a result of a functional impairment of her cellular immune response. Within 1 to 2 days, not only the wart injected with interferon-gamma, but also other warts, became erythematous and swollen, giving a lichen planus-like appearance. Without additional injections of interferon-gamma, all warts disappeared completely, leaving slight pigmentation. Interferon-gamma would be most effective when used with, rather than instead of, other immunotherapy.

The systemic administration of gamma interferon inhibits collagen synthesis and acute inflammation in a murine skin wounding model

The ability of gamma interferon (IFN-gamma) to affect cutaneous collagen synthesis in vivo was examined in a murine wounding model. Reproducible areas of full-thickness skin necrosis were produced by argon laser radiation. Mice received recombinant murine IFN-gamma (rMuIFN-gamma) (8.7 X 10(3) units/hr) over 14 d via osmotic pumps implanted subcutaneously or intraperitoneally. At 14 and 21 d after wounding, there was less fibrous tissue in healing scars of treated animals as determined by light and transmission electron microscopy. Associated with the decrease in connective tissue was an increase in the acid mucopolysaccharide content of healing scars, which was largely hyaluronate. Quantitative image analysis of electron micrographs confirmed that less collagen was present in healing scars of animals receiving rMuIFN-gamma. The mean cross-sectional area of collagen fibers was smaller in specimens from treated mice, but no difference was seen in the size of collagen fibrils. The time required to obtain full skin closure was also delayed 23%-27% in treated animals. Using this injury model, we also found that rMuIFN-gamma significantly reduced the degree of perilesional erythema surrounding the laser injury sites and, in the first 6 d after wounding, the degree of polymorphonuclear infiltrate present histologically at lesional sites. Indeed, rMuIFN-gamma also decreased the cutaneous accumulation of neutrophils induced by known proinflammatory mediators, such as interleukin 1 and activated serum. Thus, systemically administered IFN-gamma not only down-regulates collagen synthesis in the skin but also modulates in a previously unrecognized manner: neutrophil accumulation at sites of tissue injury in vivo.

T lymphocytes and monocytes bind to keratinocytes in frozen sections of biopsy specimens of normal skin treated with gamma interferon

When 2 mm punch biopsy specimens of normal skin are incubated with gamma interferon (IFN-gamma), the keratinocytes are induced to express intercellular adhesion molecule-1 (ICAM-1). Lymphocytes and monocytes that express lymphocyte function-associated antigen-1 (LFA-1) bind to cultured keratinocytes expressing ICAM-1. We have developed an in vitro adherence assay using frozen sections of normal skin that have been incubated with IFN-gamma, and then overlaid by peripheral blood mononuclear leukocytes. Although peripheral blood mononuclear leukocytes do not bind to the epidermal keratinocytes of untreated skin sections, after exposure of the skin to IFN-gamma the peripheral blood mononuclear leukocytes prominently bind to the epidermal keratinocytes that express ICAM-1. The binding by peripheral blood mononuclear leukocytes is increased approximately twofold by activation with phorbol ester treatment. The temperature dependence and kinetics of this adherence reaction reveal no binding at 8 degrees C, good binding at 24 degrees C, and optimal binding at 37 degrees C, reaching a maximal extent by 60 minutes. The adherence reaction is blocked either by pretreating the peripheral blood mononuclear leukocytes with LFA-1 antibody or the IFN-gamma-exposed skin specimen with ICAM-1 antibody. The immunophenotypic analysis of the adherent peripheral blood mononuclear leukocytes to epidermal keratinocytes revealed that most cells activated by 12-O-tetradecanoyl-phorbol-13-acetate are T lymphocytes, with CD8+ T cells binding slightly better than CD4+ T cells, with a smaller population of monocytes. These results provide additional support for a role of LFA-1, ICAM-1, and IFN-gamma in modulating keratinocyte-lymphocyte interactions.(ABSTRACT TRUNCATED AT 250 WORDS)