Recombinant gamma interferon differentially regulates class II antigen expression and biosynthesis on cultured normal human keratinocytes

Keratinocytes costimulate naive human T cells via CD2: a potential target to prevent the development of proinflammatory Th1 cells in the skin

The interplay between keratinocytes and immune cells, especially T cells, plays an important role in the pathogenesis of chronic inflammatory skin diseases. During psoriasis, keratinocytes attract T cells by releasing chemokines, while skin-infiltrating self-reactive T cells secrete proinflammatory cytokines, e.g., IFNγ and IL-17A, that cause epidermal hyperplasia. Similarly, in chronic graft-versus-host disease, allogenic IFNγ-producing Th1/Tc1 and IL-17-producing Th17/Tc17 cells are recruited by keratinocyte-derived chemokines and accumulate in the skin. However, whether keratinocytes act as nonprofessional antigen-presenting cells to directly activate naive human T cells in the epidermis remains unknown. Here, we demonstrate that under proinflammatory conditions, primary human keratinocytes indeed activate naive human T cells. This activation required cell contact and costimulatory signaling via CD58/CD2 and CD54/LFA-1. Naive T cells costimulated by keratinocytes selectively differentiated into Th1 and Th17 cells. In particular, keratinocyte-initiated Th1 differentiation was dependent on costimulation through CD58/CD2. The latter molecule initiated STAT1 signaling and IFNγ production in T cells. Costimulation of T cells by keratinocytes resulting in Th1 and Th17 differentiation represents a new explanation for the local enrichment of Th1 and Th17 cells in the skin of patients with a chronic inflammatory skin disease. Consequently, local interference with T cell-keratinocyte interactions may represent a novel strategy for the treatment of Th1 and Th17 cell-driven skin diseases.

Human blood basophils do not act as antigen-presenting cells for the major birch pollen allergen Bet v 1

BACKGROUND

Several studies in mice have recently shown that basophils can act as antigen-presenting cells (APC) inducing Th2-mediated immune responses against parasites or protease allergens. The aim of this study was to investigate whether human basophils function as APC for the major birch pollen allergen Bet v 1.

METHODS

Fluorescently labeled Bet v 1 was used to assess surface binding and internalization of allergen by basophils and different types of APC from birch pollen-allergic and nonallergic individuals. Sorted basophils were analyzed in terms of up-regulation of MHC class II and co-stimulatory molecules in the absence and presence of IL-3 and IFN-γ by flow cytometry. Expression of proteins crucial for antigen presentation, namely cathepsin S and invariant chain, was determined. Basophils were used as APC in co-culture experiments with Bet v 1-specific T-cell clones (TCCs).

RESULTS

Basophils from birch pollen-allergic donors very efficiently bound Bet v 1 through IgE/FcεRI complexes on their surface. In contrast to professional APC, basophils did not internalize allergen and expressed marginal levels of cathepsin S and invariant chain. HLA-DP, HLA-DQ, CD80/CD86, and CD40 were absent from purified basophils even when stimulated with IL-3 plus IFN-γ. IL-3/IFN-γ marginally up-regulated HLA-DR. Bet v 1-pulsed basophils failed to induce proliferative and cytokine responses in Bet v 1-specific, HLA-DR-restricted TCCs.

CONCLUSION

Human basophils neither internalize, process nor present Bet v 1. Because Bet v 1 is a highly relevant allergen, we conclude that basophils play no role as APC in IgE-mediated allergy in humans.

A modular view of cytokine networks in atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease known for its complex pathophysiology involving several immune pathways. In the lesion, signals from barrier disruption, allergens, and microbial colonization are integrated and transmitted to diverse immune cell types, which initiate and maintain the disease. Cytokines are critical in the allergic intercellular communication networks. This review focuses on up-to-date knowledge on the role of cytokines in AD, including recently described functions as well as novel cellular sources. We propose three modules defined as the cellular source of groups of cytokines: (1) keratinocytes, (2) innate immune cells, and (3) T cells. This view enables to better position the function of novel cytokine players, such as thymic stromal lymphopoetin, IL-21, IL-25, and IL-33, in linking different modules and ultimately leading to the allergic inflammatory phenotype. Persistent efforts in the detailed characterization of cytokine networks will be fundamental for the understanding of the complex pathogenic mechanisms of the disease and for guiding targeted therapeutic interventions.

The epidermis as an adjuvant

It is now clear that the epidermis has an active role in local immune responses in the skin. Keratinocytes are involved early in inflammation by providing first-line innate mechanisms and, in addition, can contribute to adaptive immune responses that may be associated with clinical disease. Moreover, keratinocytes are capable of enhancing and shaping the outcome of inflammation in response to stimuli and promoting particular types of immune bias. Through understanding the underlying mechanisms, the role of keratinocytes in disease pathogenesis will be further defined, which is likely to lead to the identification of potential targets for prophylactic or therapeutic intervention.

StrataGraft skin substitute is well-tolerated and is not acutely immunogenic in patients with traumatic wounds: results from a prospective, randomized, controlled dose escalation trial

OBJECTIVE

The goal of this study was to assess the immunogenicity and antigenicity of StrataGraft skin tissue in a randomized phase I/II clinical trial for the temporary management of full-thickness skin loss.

BACKGROUND

StrataGraft skin tissue consists of a dermal equivalent containing human dermal fibroblasts and a fully stratified, biologically active epidermis derived from Near-diploid Immortalized Keratinocyte S (NIKS) cells, a pathogen-free, long-lived, consistent, human keratinocyte progenitor.

METHODS

Traumatic skin wounds often require temporary allograft coverage to stabilize the wound bed until autografting is possible. StrataGraft and cadaveric allograft were placed side by side on 15 patients with full-thickness skin defects for 1 week before autografting. Allografts were removed from the wound bed and examined for allogeneic immune responses. Immunohistochemistry and indirect immunofluorescence were used to assess tissue structure and cellular composition of allografts. In vitro lymphocyte proliferation assays, chromium-release assays, and development of antibodies were used to examine allogeneic responses.

RESULTS

One week after patient exposure to allografts, there were no differences in the numbers of T or B lymphocytes or Langerhans cells present in StrataGraft skin substitute compared to cadaver allograft, the standard of care. Importantly, exposure to StrataGraft skin substitute did not induce the proliferation of patient peripheral blood mononuclear cells to NIKS keratinocytes or enhance cell-mediated lysis of NIKS keratinocytes in vitro. Similarly, no evidence of antibody generation targeted to the NIKS keratinocytes was seen.

CONCLUSIONS

These findings indicate that StrataGraft tissue is well-tolerated and not acutely immunogenic in patients with traumatic skin wounds. Notably, exposure to StrataGraft did not increase patient sensitivity toward or elicit immune responses against the NIKS keratinocytes. We envision that this novel skin tissue technology will be widely used to facilitate the healing of traumatic cutaneous wounds.This study was registered at www.clinicaltrials.gov (NCT00618839).

B7-1 induces immunosuppression when expressed in cultured neonatal mice keratinocytes

BACKGROUND

Chimeric (allo-auto or even xeno-auto) cultured keratinocyte grafting did not exhibit obvious acute rejection or chronic rejection. Although cultured murine keratinocytes were recognized by allogenic CD8+ T cells, they were not rejected. The precise mechanisms underlying this process were unclear. To analyze how keratinocytes attenuated the immune response, we investigated the effect of culturing on neonatal murine keratinocytes and their immunomodulatory properties.

METHODS

Keratinocytes isolated and purified from BALB/c and C57BL/6 neonatal mice were cultured for 7 days. The expression of B7-1, B7-2, B7-H1 and MHC-I was examined by semi-quantitative RT polymerase chain reaction (PCR), fluorescence microscopy and flow cytometry. Cytotoxicity and mixed lymphocyte response (MLR) assays were performed to determine the effects of keratinocytes on cytotoxic T-lymphocyte (CTL) mediated cell lysis and lymphocyte proliferation.

RESULTS

B7-1 was highly expressed in cultured, proliferating murine keratinocytes while no expression of B7-2 and B7-H1 was found. Keratinocytes that expressed B7-1 decreased CTL-mediated cell lysis by an interaction between B7-1 and CTLA-4. In addition, autologous keratinocytes but not allogeneic keratinocytes significantly suppressed auto-specific lymphocyte proliferation in a dose-dependent manner. The modulation was dependent on B7-1 expression and its interaction with CTLA-4.

CONCLUSIONS

Cultured murine keratinocytes expressed B7-1, but not B7-2 or B7-H1. The keratinocytes attenuated CTL-mediated lysis and suppressed lymphocyte proliferation via an interaction with B7-1 and CTLA-4. Therefore, separate expression of B7-1 induced immunosuppression. Non-professional APCs (antigen presenting cells) which separately express B7-1 may possess an ability to induce immunotolerance and thus act as a regulatory APC.

Critical role of indoleamine 2,3-dioxygenase in tumor resistance to repeated treatments with targeted IFNgamma

Targeted delivery of IFNgamma to tumors has been achieved by fusing this cytokine with GCNGRC, a tumor neovasculature homing peptide. Although the therapeutic efficacy of this protein (called IFNgamma-NGR) in animal models is greater than that of IFNgamma, frequent administrations of IFNgamma-NGR may result in lower efficacy and tumor resistance. We investigated the role of indoleamine 2,3-dioxygenase (IDO), an IFNgamma-inducible enzyme that may down-regulate T cells by affecting local tryptophan catabolism in tumor resistance to repeated treatments with IFNgamma-NGR. The study was carried out in immunocompetent mice and in nu/nu mice bearing RMA lymphoma, B16F melanoma, or WEHI-164 fibrosarcoma and in vitro using cultured tumor cells. IDO activity was increased in lymphoma homogenates after multiple treatments with IFNgamma-NGR but not after a single treatment. Coadministration of 1-methyl-tryptophan, an inhibitor of IDO, increased tumor responses to multiple treatments in the lymphoma, melanoma, and fibrosarcoma models. No synergism between IFNgamma-NGR and 1-methyl-tryptophan was observed in vitro in tumor cell proliferation assays or in nu/nu tumor-bearing mice, suggesting that the antitumor effect was host mediated. We conclude that IDO is critically involved in tumor resistance to repeated treatments with IFNgamma-NGR, likely causing excessive stimulation of tryptophan catabolism and inhibiting antitumor immune mechanisms. Coadministration of IFNgamma-NGR with IDO inhibitors could represent a new strategy for increasing its antitumor activity.

Anti-lymphocyte function associated antigen-1 inhibits T-helper 2 function of human allergen-specific CD4+ T cells

BACKGROUND

Blockade of lymphocyte function associated antigen-1 (LFA-1) is proving successful in the management of psoriasis and other inflammatory skin conditions including atopic dermatitis (AD), but the dependence of allergen-specific CD4+ T-cell function on LFA-1 has not been studied extensively.

OBJECTIVES

We sought to investigate the potential ability of LFA-1 inhibition to influence keratinocyte presentation of allergen to specific T-helper (Th) 2 cell clones.

METHODS

Using human leucocyte antigen class II tetrameric complexes, we generated Der p 1-specific DRB1*1501-restricted CD4+ T-cell lines (n=5) and clones (n=4) from the peripheral blood of five adults with AD.

RESULTS

Using doses of anti-LFA-1 present in vivo, we observed significant inhibition (P<0.05) of allergen-specific CD4+ T-cell production of interleukin-4 with such inhibition occurring during presentation of allergen by keratinocytes.

CONCLUSIONS

These data show that at doses present in vivo, LFA-1 blockade inhibits keratinocyte presentation to allergen-specific Th2 cells, suggesting one mechanism through which anti-LFA-1 may be beneficial therapeutically.

Human keratinocyte induction of rapid effector function in antigen-specific memory CD4+ and CD8+ T cells

The ability of human keratinocytes to present antigen to T cells is controversial and, indeed, it has been suggested that keratinocytes may promote T cell hyporesponsiveness. Furthermore, it is unclear whether keratinocytes can process antigen prior to MHC class I and class II presentation. We tested the ability of keratinocytes to induce functional responses in epitope-specific CD4+ and CD8+ memory T cells using peptides, protein and recombinant expression vectors as sources of antigen. Keratinocytes were able to efficiently process and present protein antigen to CD4+ T cells, resulting in cytokine secretion (Th1 and Th2). This interaction was dependent on keratinocyte expression of HLA class II and ICAM-1, which could be induced by IFN-gamma. In addition, keratinocytes could present virally encoded or exogenous peptide to CD8+ T cells, resulting in T cell cytokine production and target cell lysis. Finally, T cell lines grown using keratinocytes as stimulators showed no loss of function. These findings demonstrate that keratinocytes are able to efficiently process and present antigen to CD4+ and CD8+ memory T cells and induce functional responses. The findings have broad implications for the pathogenesis of cutaneous disease and for transcutaneous drug or vaccine delivery.

Transfection of CD40 in a human oral squamous cell carcinoma keratinocyte line upregulates immune potency and costimulatory molecules

BACKGROUND

There is upregulation of class II molecules of the major histocompatibility complex (MHC) by keratinocytes in oral squamous cell carcinoma (OSCC) and inflammatory diseases such as lichen planus. The significance of this expression, or whether it is accompanied by upregulation of membrane-bound costimulatory molecules, is unknown.

OBJECTIVES

To compare the expression of CD40, CD80, CD86, MHC class II and intercellular adhesion molecule-1 (ICAM-1), and the ability to induce allogeneic T-lymphocyte proliferation in vitro, of a CD40- OSCC cell line, its CD40+ transfected derivative and null transfectants.

METHODS

OSCC cell lines and purified T lymphocytes were cocultured and T cell proliferation recorded. Phenotypes were analysed by flow cytometry.

RESULTS

After T lymphocyte proliferation, which all OSCC cell lines were able to induce, there was upregulation of MHC class II and ICAM-1. However, the CD40+ transfectants were the most immunologically potent and were the only cells to show increased expression of CD86 (as well as further upregulation of CD40 and a statistically insignificant rise in CD80). The effects of blocking antibodies on T-cell proliferation were only statistically significant with the CD40+ transfectants.

CONCLUSIONS

While not essential, expression of CD40 by OSCC cells is necessary for optimal induction of allogeneic T lymphocytes, possibly because of concurrent upregulation of other membrane-bound costimulatory molecules.

Targeted delivery of IFNgamma to tumor vessels uncouples antitumor from counterregulatory mechanisms

Because of its immunomodulatory and anticancer activities, IFNgamma has been used as an anticancer drug in several clinical studies, unfortunately with modest results. Attempts to increase the response by increasing the dose or by repeated continuous injection often resulted in lower efficacy, likely due to counterregulatory effects. We show here that targeted delivery of low doses of IFNgamma to CD13, a marker of angiogenic vessels, can overcome major counterregulatory mechanisms and delay tumor growth in two murine models that respond poorly to IFNgamma. Tumor vascular targeting was achieved by coupling IFNgamma to GCNGRC, a CD13 ligand, by genetic engineering technology. The dose-response curve was bell-shaped. Maximal effects were induced with a dose of 0.005 microg/kg, about 500-fold lower than the dose used in patients. Nontargeted IFNgamma induced little or no effects over a range of 0.003 to 250 microg/kg. Studies on the mechanism of action showed that low doses of targeted IFNgamma could activate tumor necrosis factor (TNF)-dependent antitumor mechanisms, whereas high doses of either targeted or nontargeted IFNgamma induced soluble TNF-receptor shedding in circulation, a known counterregulatory mechanism of TNF activity. These findings suggest that antitumor activity and counterregulatory mechanisms could be uncoupled by tumor vascular targeting with extremely low doses of IFNgamma.

Survival of Apligraf in acute human wounds

Apligraf consists of bovine collagen dermis seeded with allogeneic male fibroblasts and keratinocytes. It is been shown to promote healing, but the length of persistence and pathological features have not been characterized previously in acute wounds. Forty-eight deep dermal wounds were created and Apligraf, a split-skin graft (SSG), or a dressing was applied. Biopsies of wounds were taken for immunohistochemical analysis and polymerase chain reaction was performed to detect the Y chromosome from Apligraf cells in 14 female wounds. Male allogeneic DNA was detected in wounds for the first 4 weeks. All subsequent time points were negative apart from one biopsy at 6 weeks. The wounds took 4-9 weeks to heal, with the Apligraf exhibiting no features of engraftment. This was in contrast to the rapid healing seen in the SSG control group. Histology revealed a more intense cellular infiltrate, but less vascularization below Apligraf compared with controls. Evidence of an epidermal-mesenchymal interaction was observed. This is the first article to elucidate the survival of Apligraf allogeneic cells in acute wounds in immunocompetent human subjects for up to 6 weeks and demonstrates that in the management of acute surgical wounds, Apligraf has a role only as a temporary biological dressing.

Langerhans cells from human oral epithelium are more effective at stimulating allogeneic T cells in vitro than Langerhans cells from skin

This report is focused on the functional capacity of Langerhans cells (LC) in the epithelium of skin and oral mucosa, which both meet different antigenic challenges. The capacity of LC from human oral and skin epithelium to provide co-stimulatory signals to T cells in vitro was compared. LC in a crude suspension of oral epithelial cells had a significantly enhanced T cell co-stimulatory capacity compared to skin epithelial cells. This applied both to cultures with concanavalin A (con-A)-stimulated syngeneic T cells and to a mixed epithelial cell lymphocyte reaction involving allogeneic T cells. The co-stimulatory capacity of oral and skin epithelial cells was reduced by >70% if monoclonal antibodies against HLA-DR, -DP and -DQ were added to the cultures with allogeneic T cells, indicating the involvement of HLA class II expressing LC. Immunohistochemistry revealed that 6% of the epithelial cells were CD1a + LC in sections from both oral and skin epithelium. Interleukin (IL)-8 production was higher in cultures of oral epithelial cells and con-A stimulated T cells than in corresponding cultures with skin epithelial cells as accessory cells. The results suggest that LC in human oral epithelium are more efficient at stimulating T cells than those of skin.

T-cell costimulatory capacity of oral and skin epithelial cells in vitro: presence of suppressive activity in supernatants from skin epithelial cell cultures

Oral Langerhans cells (LC) have better T-cell costimulatory capacity than skin LC. In this study factors affecting this capacity have been assessed in a mixed epithelial cell lymphocyte reaction (MELR) assay. Flow cytometry analysis of freshly recovered cells revealed major histocompatibility complex (MHC) class II molecule expression on 7.5% of the oral epithelial cells and 9.7% of the skin epithelial cells. Monoclonal anti class II antibodies significantly reduced the T-cell proliferation in the MELR. Pretreatment of skin epithelial cells with interleukin-1beta, tumour necrosis factor-alpha or interferon (IFN)-gamma did not affect the MELR proliferation, but incubation with IFNgamma significantly suppressed the T-cell response. Transfer of supernatants from cultures of skin epithelial cells and allogeneic T cells to cultures of oral epithelial cells and T cells resulted in a reduced T-cell proliferation while supernatants from oral epithelial cells and T cells did not reduce proliferation. The higher proliferation in cultures of T cells and oral epithelial cells than in cultures containing skin epithelial cells may be due to the presence of a suppressive factor in the skin epithelial cell suspensions.

Vaginal immunity in the HSV-2 mouse model

Herpes simplex virus type 2 (HSV-2) is a sexually transmitted pathogen that infects the genital tract. Efforts to develop vaccines to protect women against this and other sexually transmitted pathogens would be facilitated by a better understanding of the immune mechanisms that protect the female reproductive tract against such infections. Such information would be invaluable in developing vaccine strategies to promote the type and magnitude of immune responses in the genital tract that would effectively protect against infection. This review focuses on recent studies using a progestin-treated adult mouse model to explore mucosal immunity to HSV-2 in the vagina. Evidence indicating a major role for both humoral and T cell immunity is presented.

Immunity to oncogenic human papillomaviruses

The establishment of human papillomavirus (HPV) infection as a major cause of several human cancer forms, notably cervical cancer, has spurred development of prophylactic and/or therapeutic HPV vaccines for prevention of cervical neoplasia. Knowledge of the immunity to HPV forms the basis for such endeavors.

METHOD

A literature review of humoral and cellular immunity to HPV. The overview on human leukocyte antigen (HLA) and cervical cancer was expanded to a formal metaanalysis, where relevant articles were located by Medline search and citation analysis and graded by preassigned quality criteria on study design.

RESULTS

The antibody response to the HPV particle is dominated by a neutralizing antibody response to a typespecific, conformationally dependent immunodominant epitope. Vaccines based on viral particles lacking the viral genome (virus-like particles, VLPs) have been highly successful in preventing and treating HPV infection in several animal model systems. In humans, the serum antibody response to VLPs is stable over time, also after the HPV infection has been cleared, resulting in HPV serology being used as a marker of cumulative HPV exposure in spite of the fact that a significant proportion of HPV-exposed subjects fail to seroconvert. More than 90% of HPV infections will clear spontaneously. The factors that determine whether an HPV infection is cleared or persists and increases the risk for cancer are not known, but cellular immunity is implicated. Several HLA class II haplotypes are associated with cervical cancer: DQw3 increases and DR13 decreases the risk for cervical cancer in general (odds ratios (OR) and 95% confidence intervals (CI): 1.25(1.15-1.37) and 0.69 (0.56-0.85), respectively); DR15 increases the risk for HPV16-carrying cancer (OR: 1.47; CI: 1.20-1.81); and DR7 may be either protective or increase the risk. Most cervical cancers have downregulated the expression of at least one HLA class I antigen, whereas class II expression is increased in infected epithelium. A Th2 cytokine profile is associated with progression to cervical cancer. HPV-antigen-specific proliferative responses have been detected in many studies, although it is not entirely clear whether these responses are HPV type specific or may be cross-reactive between HPV types. Specific cytotoxic T lymphocyte (CTL) responses were originally reported in only a minority of infected subjects, typically cancer patients, but with advancing technology, specific CTLs can be stimulated from about half of the women with HPV-carrying disease. In animal model systems, CTL responses can mediate clearance.

CONCLUSION

The antibody response to HPV is a mediator of type-specific protective immunity, which forms the basis for prophylactic vaccine candidates. The cellular immunity to HPV is implicated as an important factor in cervical carcinogenesis, but the main targets and types of responses that mediate HPV clearance are not established.

Alpha and gamma interferons inhibit herpes simplex virus type 1 infection and spread in epidermal cells after axonal transmission

The ability of alpha interferon (IFN-alpha) and IFN-gamma to inhibit transmission of herpes simplex virus type 1 (HSV-1) from neuronal axon to epidermal cells (ECs), and subsequent spread in these cells was investigated in an in vitro dual-chamber model consisting of human fetal dorsal root ganglia (DRG) innervating autologous skin explants and compared with direct HSV-1 infection of epidermal explants. After axonal transmission from HSV-1-infected DRG neurons, both the number and size of viral cytopathic plaques in ECs was significantly reduced by addition of recombinant IFN-gamma and IFN-alpha to ECs in the outer chamber in a concentration-dependent fashion. Inhibition was maximal when IFNs were added at the same time as the DRG were infected with HSV-1. The mean numbers of plaques were reduced by 52% by IFN-alpha, 36% by IFN-gamma, and by 62% when IFN-alpha and IFN-gamma were combined, and the mean plaque size was reduced by 64, 43, and 72%, respectively. Similar but less-inhibitory effects of both IFNs were observed after direct infection of EC explants, being maximal when IFNs were added simultaneously or 6 h before HSV-1 infection. These results show that both IFN-alpha and IFN-gamma can interfere with HSV-1 infection after axonal transmission and subsequent spread of HSV-1 in ECs by a direct antiviral effect. Therefore, both IFN-alpha and -gamma could contribute to the control of HSV-1 spread and shedding in a similar fashion in recurrent herpetic lesions.

Langerhans cells and T cells in oral graft versus host disease and oral lichen planus

Chronic graft versus host disease (cGVHD) of the oral mucosa, following allogeneic stem cell transplantation, and oral lichen planus (OLP) are both mucosal diseases where the immune system is involved in the pathogenesis. Although the aetiology of the two conditions is different, they present with a similar clinical appearance. This study compares the two diseases regarding the distribution of cells, which are expressing cell surface markers of interest for inflammatory responses. Monoclonal antibodies (MoAbs) were used in standard immunohistochemical procedures. CD1a+, CD80+ and CD86+ cells in the epithelium of OLP- and cGVHD lesions had the dendritic morphology of Langerhans cells (LC). Higher frequencies of CD1a+ LC as well as CD25+ cells were observed in the OLP epithelium than in the cGVHD epithelium. The OLP lesions showed higher frequencies of subepithelial cells expressing CD1a, CD86, CD4, CD8 and CD25 than the cGVHD lesions. Notably there was a significantly higher frequency of CD25+ cells in the epithelium and the connective tissue of OLP than in cGVHD. These cells might represent regulatory T cells. In conclusion, cGVHD and OLP show marked differences at the cellular level despite similar clinical appearance. Hence, the findings indicate differences in the regulation of the inflammatory response between the two conditions.

Modification of fibroblast gamma-interferon responses by extracellular matrix

Fibroblasts from scaffold-based three-dimensional human cultures have been demonstrated to colonize ulcer wound beds and persist for at least 6 mo without rejection. This study examines the expression in these cultures of molecules associated with activation of the immune system in acute rejection. Studies in monolayer cultures showed that fibroblasts expressed CD40 at about 10% of the surface density seen in umbilical vein endothelial cells, whereas HLA-DR was undetectable. In these cultures, both molecules were induced by gamma-interferon. In scaffold-based three-dimensional cultures, however, a majority of the fibroblasts showed little induction of CD40 and HLA-DR in response to gamma-interferon, although HLA class I expression was increased. Fibroblasts re- isolated from the three-dimensional cultures and cultured in monolayers recovered HLA-DR induction in response to gamma-interferon. Fibroblasts cultured in an alternative three-dimensional system using collagen gels showed CD40 and HLA-DR induction by gamma-interferon in the same manner as monolayer cultures. Comparison of phosphorylation of signal transducer and activator of transcription 1 on tyrosine-701 showed it to be similar in monolayer and three-dimensional culture, and phospho-signal transducer and activator of transcription 1 moved into the nucleus. Induction of the class II transcription activator was greatly reduced, however. We propose that interaction of fibroblasts with the fibroblast-derived extracellular matrix is an important modulator of gamma-interferon responsiveness and that this interaction may play a role in the low immunogenicity of allogeneic fibroblasts grown on scaffolds.

Immunohistologic responses within dermal metastatic melanoma lesions of patients treated with a synthetic peptide vaccine

Three patients with dermal metastatic melanoma lesions responding to a synthetic peptide vaccine (g209-2M) derived from the sequence of gp100 melanoma-associated antigen, along with either IL-2 or granulocyte-monocyte colony-stimulating factor were studied to characterize the immunologic response occurring within and around the lesions during therapy. Standard immunocytochemical techniques were used to study the T-cell response (CD3, CD4, and CD8), the B-cell response (CD20), and the expression of class II major histocompatibility complex (HLA-DR) antigens. Between 40 and 65 days after the initiation of vaccine therapy (more than 3 weeks after the second dose of vaccine), the gross tumor size decreased and the tumors from all three patients showed substantial histologic regression associated with increased numbers of tumor-infiltrating lymphocytes and melanophages. The increased lesional tumor-infiltrating lymphocytes consisted of CD3+ T cells and very few CD20+ B cells. In two of the three patients, the T-cell infiltrate occurring during the initial tumor regression consisted predominantly of CD8+ cells. The number of perivascular T cells surrounding small vessels adjacent to melanoma lesions also increased during the time of peak histologic tumor regression. Also during the course of vaccine therapy, the expression of HLA-DR by vascular endothelial cells of the small vessels adjacent to lesions increased in all three patients, and elevated endothelial expression of HLA-DR was maintained in two of the three patients. These results show that patients with metastatic melanoma, who responded to melanoma vaccine therapy, had a predominantly CD8+ T-cell infiltrate associated with a loss of tumor cells. As the tumor cells diminished, they were replaced by heavily pigmented melanophages.

Induction of transforming growth factor-beta 1 production in human cells by herpes simplex virus

Transforming growth factor-beta (TGF-beta) is a cytokine of particular interest in human retrovirus infections because it can abrogate antigen-specific cellular activation. Although TGF-beta production has been observed in HIV infections, there is no evidence that herpes simplex virus (HSV)-stimulated human cells produce this cytokine. Here we present evidence, for the first time, that in vitro infection of human mononuclear cells with HSV type 1 (HSV-1) induced the release of TGF-beta1 protein. The production of this cytokine was time dependent and was found highly significant (p < 0.001) after 48 h. In addition, we observed that the secretion of TGF-beta1 was dependent on the concentration of human cells. It was found that virus needs to replicate in human cells for the production of TGF-beta1, as UV-inactivated virus did not induce significant production of cytokine protein. Interestingly, increased HSV-1-induced TGF-beta1 production in cultures containing antiinterleukin (IL)-12 or antiinterferon (IFN)-gamma antibodies was observed, whereas an irrelevant antibody had no effect on the production of this cytokine. Taken together, these findings indicate that human cells synthetize TGF-beta1 in response to HSV-1 and at the same time suggest that HSV-1-induced TGF-beta1 production may be one of the mechanisms by which HSV can at least partly evade activation of the host immune system.

The role of gamma interferon in immune resistance to vaginal infection by herpes simplex virus type 2 in mice

We investigated the role of interferon gamma (IFN-gamma) in a mouse model of immunity to vaginal infection by herpes simplex virus type 2 (HSV-2). Within 8 h after immune mice were challenged intravaginally with HSV-2, IFN-gamma concentrations in vaginal secretions reached levels that can be antiviral in vitro. This rapid synthesis of IFN-gamma occurred in immune-challenged mice but not in nonimmune-challenged mice, indicating that it required memory T cells. Immunostaining and in situ hybridization revealed that the IFN-gamma was synthesized by cells whose morphological appearance suggested that they were lymphocytes and macrophage-like cells in the mucosa. The presence of IFN-gamma in vaginal secretions was correlated with upregulation of MHC class II antigens in the epithelium and with vigorous (30-fold) recruitment of T and B lymphocytes into the vagina. In vivo administration of anti-IFN-gamma to immune mice 17 h before virus challenge blocked the subsequent appearance of IFN-gamma in vaginal secretions, blocked upregulation of class II antigens, blocked adherence of T cells to endothelium and their recruitment into the vagina, and markedly reduced immunity against reinfection of the vaginal epithelium.

Langerhans cells from oral epithelium are more effective in stimulating allogeneic t-cells in vitro than Langerhans cells from skin epithelium

Dendritic cells, such as Langerhans cells (LC), in different ectodermal compartments may have different functional capabilities. The present study was undertaken to compare oral Langerhans cells (LC) with those of the epidermis in terms of their ability to co-stimulate T-cells in vitro. A Mixed Epithelial Cell Lymphocyte Reaction (MELR) and a mitogen-driven (concanavalin A) T-cell proliferation assay were used. In both assays, LC in a crude cell suspension of freshly isolated oral epithelial cells were found to be five times more effective in mediating T-cell proliferation than freshly isolated epidermal LC. Twenty-four-hour cell culture at 37 degrees C enhanced the T-cell response in the MELR compared with cells cultured at 4 degrees C. This applied to both skin and oral epithelial cells. Oral and skin epithelial cell suspensions depleted of LC lost the capacity to stimulate allogeneic T-cells. Incubation of the epithelial cell suspensions with recombinant Granulocyte/Macrophage-Colony Stimulating Factor (rGM-CSF) did not enhance the co-stimulating capacity of the LC. Titration of different numbers of oral and skin LC to T-cells showed that skin LC were never able to reach more than 44% of the maximal stimulatory capacity of oral LC. Data show that oral LC are more efficient than skin LC in providing co-stimulatory signals to T-cells, suggesting a difference in functional capacity between the two cell populations.

Interferon-gamma-stimulated human keratinocytes express the genes necessary for the production of peptide-loaded MHC class II molecules

Keratinocytes exposed to interferon (IFN)-gamma synthesize major histocompatibility complex class II antigens both in vivo and in vitro; however, the expression of class II accessory genes has not yet been investigated. In this study, we examined the capacity of normal human keratinocytes activated with IFN-gamma to express HLA-DR, HLA-DM, and invariant chain genes as well as two major transcription regulatory genes, class II transactivator and RFX5. Cultured keratinocytes were shown to synthesize low levels of DM alpha, invariant chain p33, and RFX5 transcription factor. Upon treatment with IFN-gamma, expression of RFX5, DM alpha, and invariant chain p33 mRNA increased, whereas class II transactivator mRNA appeared de novo, followed by the expression of DR alpha, DMbeta, and invariant chain p41 genes. Western blot analysis showed that both p33 and p41 invariant chain forms and DM became detectable in keratinocytes after stimulation with IFN-gamma, with a higher p41/p33 ratio compared with Raji B cells. Finally, HLA-DR molecules present on IFN-alpha-treated keratinocytes were shown to be remarkably resistant to sodium dodecyl sulfate denaturation at room temperature, a feature that class II molecules acquire when their groove is properly loaded with peptide. These results suggest that human keratinocytes activated with IFN-gamma possess the biochemical requirements for the generation of functional class II peptide complexes.

Cytokine regulation of major histocompatibility complex antigen expression by human oral and skin keratinocytes

The expression, and cytokine modulation, of major histocompatibility complex (MHC) class I and class II molecules on oral and skin keratinocytes were compared in cell culture. Both cell types expressed class I, but not class II, constitutively. However, stimulation with interferon-gamma, but not interleukin-1 alpha, and -1 beta, tumour necrosis factor-alpha or lymphotoxin, induced increased expression of class I and de-novo expression of HLA-DR on both cell types. Oral keratinocytes differed from skin keratinocytes in that they exhibited greater sensitivity to interferon-gamma stimulation and higher stimulated expression of both class I and HLA-DR. In addition, interferon-gamma stimulated oral, but not skin, keratinocytes to express HLA-DP and -DQ. These observations suggest that, like skin keratinocytes, under certain conditions, oral keratinocytes may be able to act as antigen-presenting cells. This may be important in the initiation and progression of some immune-mediated mucocutaneous diseases. Moreover, differences in MHC expression may help to explain differences in the presentation of these diseases on the skin and oral mucosa.

The myxoma virus-soluble interferon-gamma receptor homolog, M-T7, inhibits interferon-gamma in a species-specific manner

The myxoma virus M-T7 protein contains significant sequence similarity to the ligand binding domain of the mammalian interferon-gamma receptors, and functions as a soluble homolog which can bind and inhibit the biological activities of rabbit interferon-gamma (Upton, C., Mossman, K., and McFadden, G. (1992) Science 258:1369-1372). M-T7, the most abundantly secreted protein from myxoma virus-infected cells, was shown to be expressed in significant biological amounts as a typical poxvirus early gene product, efficiently secreted at early times of infection to levels that exceed 5 x 10(7) molecules/cell, and function as a stable inhibitory protein in infected cell supernatants until late times of infection. M-T7 was specific in binding and inhibiting rabbit interferon-gamma, and did not bind either human or murine interferon-gamma. Scatchard analysis of rabbit interferon-gamma binding curves yielded a single high affinity binding site on M-T7, with a Kd of 1.2 x 10(-9) M, which is comparable to the affinity between soluble forms of cellular interferon-gamma receptors and their cognate ligands. In comparison, rabbit interferon-gamma was shown to bind its cellular receptor with a Kd of 5.9 x 10(-10) M, again comparable to the affinity of membrane bound forms of other mammalian interferon-gamma receptors for interferon-gamma. Thus, the myxoma virus M-T7 protein is a functional soluble interferon-gamma receptor homolog which binds and inhibits interferon-gamma with high affinity in a species-specific manner.

Effects of cytokines on the gamma interferon-induced tryptophanyl-tRNA synthetase expression by human keratinocytes

Incubation of human keratinocytes with gamma interferon (gamma-IFN) has been shown to potently induce the synthesis of a 53 kDa protein which was recently identified as tryptophanyl-tRNA synthetase (TRS). However, in spite of the high sensitivity of cultured keratinocytes to TRS induction by gamma-IFN, the study of inflammatory skin lesions has allowed the detection of the protein only in a few cases, suggesting regulatory mechanisms from soluble endogenous mediators with antagonistic activity on the induction of TRS by gamma-IFN. Among these mediators, we wondered whether cytokines selected for possible anti-inflammatory activity and potentially derived from activated resident skin cells, such as IL-4, IL-10, TNF-alpha and TGF-beta, may be involved in the modulation of the keratinocyte TRS expression. To assess this possibility, we investigated the modulation of the synthesis of TRS by human cultured keratinocytes upon stimulation by various gamma-IFN/cytokine combinations. The effects were evaluated by immunoblotting assay revealed by enhanced chemiluminescence, with the aid of a specific antibody to the TRS protein. Results failed to demonstrate any effect of the tested cytokines, whether on the basal level of the TRS, or on the gamma-IFN-induced enzyme expression in keratinocytes. It is thus unlikely that such cytokines can account for the infrequency of the TRS detection in inflammatory skin processes. Further investigations of alternative working hypothesis should help elucidate the regulation of TRS in human keratinocytes.

Gamma interferon potently induces tryptophanyl-tRNA synthetase expression in human keratinocytes

Incubation of human keratinocytes with gamma interferon (gamma-IFN) induces the synthesis of a 53-kDa protein of unknown nature and function. We report the identification of this protein through amino acid microsequencing. The NH2-terminal amino acid sequence of the 53-kDa antigen demonstrated that this protein was tryptophanyl-tRNA synthetase (Frolova et al, Gene 109:291-296, 1991, Genbank accession number 61715). This result was validated by the sequencing of tryptic peptides. Identification of the 53-kDa gamma-IFN-induced protein was confirmed by immunoblotting with an antiserum directed against beef pancreas tryptophanyl-tRNA synthetase. Northern blot analysis using a synthetic oligonucleotidic 32P-labeled probe evidenced a 3.1-kb transcript in gamma-IFN-treated cells indicating that the gene was regulated at the pre-translational level. These data show that gamma-IFN potently induces in keratinocytes the expression of an enzyme directly involved in protein biosynthesis. Elevated levels of tryptophanyl-tRNA synthetase in treated cultured keratinocytes might be involved in the cell-growth-inhibitory activity of gamma interferon.

Cytokines in the vitreous of patients with proliferative diabetic retinopathy

Sixteen vitreous and paired serum samples from 13 patients with proliferative diabetic retinopathy, vitreous samples from seven cadaveric control subjects, and aqueous humor samples from 15 normal control subjects were assayed for the cytokines interleukin-1, tumor necrosis factor-alpha, interleukin-6, and interferon-gamma. Interleukin-6 was detected in 15 of 16 vitreous samples (94%) from diabetic patients, but it was not detected in any of the aqueous humor samples. Vitreous interleukin-6 levels positively correlated with ocular disease activity. Interleukin-1 was detected in seven of 16 vitreous samples (44%) and in four of ten aqueous humor samples (40%), whereas tumor necrosis factor-alpha and interferon-gamma were never detected in vitreous or aqueous fluid. Serum samples from diabetic patients and control subjects contained comparable low levels of interleukin-6. Interleukin-1, tumor necrosis factor-alpha, and interferon-gamma were not found in any of the sera. Because interleukin-6 can function as B-cell differentiation factor, this cytokine may have a role in immunoglobulin deposition in the ocular tissues and in the immunopathologic characteristics of proliferative retinopathy.

Induction of MHC antigens by tumour cell lines in response to interferons

The induction of major histocompatibility complex antigens by interferons (IFN) on 17 established tumour cell lines was investigated by radio binding. One bladder (Fen) and two testis lines (Tera I and Ha) lacked class I antigens and IFN-gamma failed to induce their expression. However, IFN-gamma upregulated these antigens on lines expressing low class I antigens (Tera II and EP2102) with little or no significant effect on high class I expressing lines (T24 and RT112). In one bladder line (Wil) IFN-gamma, whilst failing to alter monomorphic class I, upregulated polymorphic HLA-A2 and A3 antigens. None of the 17 lines expressed class II antigens, but could all be induced by IFN-gamma except T24, TccSup, Tera II and Lan lines. This defect was not due to the absence of IFN-gamma receptor, since under the same conditions intracellular adhesion molecule 1 was upregulated. IFN-alpha, whilst failing to have any effect on class II, induced class I antigens. IFN-beta showed no activity on either class I or II antigens when used alone. However, in combination, it inhibited IFN-gamma induced class II antigens. Thus, it may be possible to study cells from fresh tumours to preselect the minority of patients who might benefit from cytokine therapy.

Expression of interferon-gamma receptors in normal and psoriatic skin

Psoriatic keratinocytes have a reduced antiproliferative response to interferon (IFN)-gamma, and HLA-DR expression is usually not observed on keratinocytes in psoriatic plaques despite the presence of activated T cells. We have therefore compared the expression of IFN-gamma receptors in psoriatic skin with that of normal human skin. Using mouse monoclonal antibodies and immunoperoxidase staining on cryostat cut sections, we detected IFN-gamma receptors on keratinocytes throughout the epidermal layers except stratum corneum in normal skin (n = 11). Biopsy specimens from involved psoriatic skin (n = 17) consistently showed a staining pattern that differed from that of normal skin in that only the lower part of epidermis reacted with the antibodies to IFN-gamma receptors, whereas the upper layers showed no or minimal staining. Expression of IFN-gamma receptors in uninvolved psoriatic skin (n = 16) did not differ from that of healthy controls. Forty-five percent of the biopsies from lesional psoriatic skin displayed ICAM-1 positive keratinocytes, and only two specimens had a limited expression of HLA-DR reactive keratinocytes. The decreased binding of antibodies against the IFN-gamma receptors in the upper part of psoriatic epidermis might be secondary to abnormal maturation of psoriatic keratinocytes or a primary defect involving abnormal modulation of IFN-gamma receptors.

Cohesion and desquamation of epidermal stratum corneum

This article attempts to provide a comprehensive review on the roles of various classes of molecules in the cohesion and desquamation of the stratum corneum. In the first part of this monograph we review the field of epidermal differentiation in vivo and vitro, describing the expression and functions of a number of key structural molecules that characterize the process. In the second part we emphasize terminal differentiation and the biogenesis of the stratum corneum. The stratum corneum is a cell layer unique to fully differentiated squamous epithelia such as skin. While it is a dead stratum, it nevertheless is in a homeostatic process of continual shedding and renewal in synchrony with basal cell replication. It is also a degradative layer containing many proteinases and glycosidases in which a variety of intracellular and intercellular macromolecules are degraded. We highlight the molecules localized within the intercorneal matrix that are most likely to play a role in cohesion and desquamation, including: glycoproteins, lipids and enzymes. Because it is difficult to study the stratum corneum and desquamation in the native tissue, we discuss a number of model systems that have been used. The stratum corneum can be dispersed into single squames in different ways; these include mechanical dispersion as well as agents such as detergents and enzymes. The solubilized molecules and the structures remaining can then be studied as to their specific roles in desquamation. Using this approach it is possible to reconstitute multilayered structures that resemble a real stratum corneum. We have shown that glycoproteins play a key role in squame reaggregation and that this process can be modulated with amino sugars in a lectin-like fashion. Cohesion and desquamation can also be studied in tissue culture. Depending on the culture system, the extent of terminal differentiation and squame accumulation varies. Yet desquamation does not normally occur. It can be induced however by the inclusion of exogenous agents such as IFN-gamma which are found in the native epidermis but are absent in vitro. Modulation of desquamation by other exogenous agents is likely to yield further knowledge of how shedding occurs in vivo. Insight has also come from studies of scaling skin disorders. The glycoprotein and lipid profiles are altered in the stratum corneum in many diseases of aberrant terminal differentiation. A number of abnormalities in the levels of cytokines and growth factors have also been reported in the lesional tissue of such diseases.(ABSTRACT TRUNCATED AT 400 WORDS)

Interferon-gamma modulates terminal differentiation and the expression of desquamin in cultured keratinocytes

Interferon (IFN)-gamma has been shown to modulate cell differentiation and the expression of cell surface molecules of cultured human keratinocytes; it also induces cell shedding. We have previously described the properties of desquamin, a cell surface adhesion molecule from the stratum corneum. We report here on the impact of IFN-gamma on the expression of desquamin. We document the related morphological changes in terminal differentiation. We cultured human keratinocytes in three different culture systems: in serum-free medium at low Ca2+ (0.1 mM), at high Ca2+ (1.5 mM), and at high Ca2+ with 10% serum. IFN-gamma (100 U/ml) was added to each culture system after overnight incubation. In all cases, IFN-gamma induced an altered phenotype, as shown by phase contrast and electron microscopy. We exposed cultured cells to antibodies to the desquamins (glycoproteins from the stratum corneum). Immunoflurescent localization and Western blotting showed that the desquamins were expressed only under culture conditions where both serum and IFN-gamma were present. The induction of desquamin expression by IFN-gamma coupled with an increase in cell shedding, suggests that we have developed a suitable culture system for the study of desquamation in vitro.

The expression of MHC class II (Ia) antigens on mouse keratinocytes following epicutaneous application of contact sensitizers and irritants

The expression of MHC class II (Ia) antigens on mouse keratinocytes was studied following both the induction and elicitation of contact sensitivity, and after primary irritant reactions. IA+ and IE+ keratinocytes were detected, using an indirect immunofluorescence assay on epidermal sheets, only after the induction and elicitation of contact sensitivity with the sensitizers oxazalone, picryl chloride and 2,4-dinitrochlorobenzene but not with formaldehyde. Ia+ keratinocytes were not detected after epicutaneous application of the non-sensitizing irritants croton oil, SDS and anthralin, or following attempted sensitization of nude mice, suggesting that the expression of Ia antigen on keratinocytes during contact sensitivity reactions is T-cell mediated. Because Ia antigen expression on keratinocytes could be detected only several days after induction or elicitation of contact sensitivity, and contact sensitization could also be demonstrated to occur independently of aberrant Ia expression, Ia+ keratinocytes cannot be involved in the initiation of these reactions. However, they might be important in exerting an immunomodulatory influence during the later stages of the responses to certain sensitizers.

Antigenic profile of human acrosyringium

The demonstration of HLA-DR on human acrosyringium has led to the suggestion that eccrine epithelium, through its interaction with certain molecules, might play an active role in epidermal immune responses. An immunohistochemical study was undertaken to identify the antigenic profile of acrosyringium in normal skin and following the intradermal administration of a T-lymphocyte-derived cytokine, interferon gamma (IFN-gamma). Acrosyringium in normal skin, in contrast to interappendageal epidermis, was found to lack CD1a+ Langerhans cells. However, antigens CD36 (OKM5) and L1 (MAC387) were uniquely expressed by keratinocytes immediately adjacent to the distal portion of acrosyringium. Constitutive expression of each class II MHC antigen, namely HLA-DR, DP and DQ was observed on luminal acrosyringial cells. EMB11 antigen (CD68), a mononuclear cell determinant, was similarly expressed on acrosyringial epithelium in normal skin. Following intradermal administration of IFN-gamma, intercellular adhesion molecule-1 (ICAM-1) (CD54) was induced on acrosyringial epithelium and the expression of HLA-DR was intensified. A range of other markers including CD3, CD4, CD8, CD11a, CD11b and CD15 were not expressed by acrosyringium either in normal skin or after administration of IFN-gamma. Expression of antigens associated with cell-mediated immune mechanisms on acrosyringium is consistent with the hypothesis that it may have an immunological role in epidermal immune responses.

MHC antigen expression in human oral squamous carcinoma cell lines

This study quantified the constitutive and interferon-gamma (IFN-gamma) stimulated expression of MHC class I (HLA-ABC and beta 2 microglobulin) and class II antigens (HLA-DR, -DP, -DQ) on normal and malignant oral keratinocytes using radioimmunoassay and immunocytochemical techniques. Normal keratinocytes and three of four malignant cell lines (H103, H157, H314) expressed MHC class I antigens constitutively; IFN-gamma increased MHC class I expression with significant changes in normals, H157 and H314. Normal keratinocytes expressed significantly more constitutive MHC class I antigens than H103 and H157 and significantly more IFN-gamma stimulated MHC class I antigens than H103, H157 and H314. MHC class II antigens predominantly were not expressed constitutively on normals, H103 and H157 but, in H314, HLA-DR, -DP and -DQ antigens were demonstrated on 35, 11 and 5 per cent of cells, respectively, and resulted in a non-coordinated pattern of expression (HLA-DR greater than -DP = -DQ). IFN-gamma induced HLA-DR on normals, H103 and H157, whilst HLA-DP and -DQ remained undetectable. In H314, IFN-gamma enhanced HLA-DR, -DP and -DQ (significant increase of HLA-DQ) but the interrelationship between these antigens was maintained (HLA-DR greater than -DP = -DQ). Normal keratinocytes expressed significantly more IFN-gamma stimulated HLA-DR than H103 and H157 but significantly less HLA-DR than H314 under similar experimental conditions. One oral malignant cell line (H191) did not express MHC class I and MHC class II antigens either constitutively or in response to IFN-gamma. The results demonstrate aberrant patterns of MHC expression (absence, enhanced, diminished) in the different malignant oral keratinocyte cell lines.

Effect of IFN-gamma on the expression of MHC class I and class II antigens in a human malignant oral epithelial cell line

This study examined the expression of major histocompatibility complex (MHC) antigens in the KB human carcinoma cell line. MHC class I antigens (HLA-ABC and beta 2microglobulin) were constitutively expressed but not significantly enhanced by interferon-gamma (IFN-gamma). By contrast, MHC class II antigens were absent or expressed minimally on unstimulated KB cells, but DR and DP were significantly stimulated in a non-coordinated pattern (HLA-DR greater than -DP greater than -DQ) by IFN-gamma.

Interleukin-1 alpha gene-transcription in murine keratinocytes is inhibited by HSV-1 infection

The effect of in vitro infection with herpes simplex virus 1 (HSV-1) on the Interleukin-1 (IL-1) activity of murine keratinocytes was investigated. IL-1 alpha mRNA synthesis was measured by the Northern blot technique, and the IL-1 protein production was measured in terms of the ability of dialysed supernatants from cultures of uninfected and HSV-1 infected keratinocytes to enhance mitogen-induced murine thymocyte proliferation. IL-1 alpha mRNA-synthesis in uninfected keratinocytes was detected 24 h and 48 h after isolation of the keratinocytes. IL-1 protein secretion by these keratinocytes was measureable at 18 h and reached a peak of 73 h, whereas intracellular and membrane-bound IL-1 protein production reached a maximum after 25 h. Keratinocytes, which had been cultured in vitro for 18 h, were infected with HSV-1 for 2 h and further cultured for an additional 4 h or 22 h before IL-1 measurements. A marked reduction of IL-1 alpha gene-expression was noted 6 hours after HSV-1-infection of keratinocytes, and nearly total shut-off was detected after infection for 24 h. Reduced gene-expression was paralleled by a reduction in the IL-1 protein secretion from the HSV-1 infected keratinocytes.

Predominantly indurated reactions to sensitizers may not cause keratinocytes to express HLA-DR

Dermal reactions to primary intradermal or appendageal sensitization are compared to predominantly dermal reactions to standard patch tests and to intradermal antigen tests. In contrast to epicutaneous spongiotic contact dermatitis, HLA-DR was only seen on skin appendages and nearby basal keratinocytes in indurated tissue reactions with the exception of the reactions with focal basal cell layer disruption and an indurated patch test performed one week post angry back syndrome. Other intradermal skin tests showed only minimal epidermal HLA-DR expression despite spongiotic epidermal changes. Predominantly dermal hypersensitivity reactions can be induced by intradermal or epicutaneous routes. They can evoke hypersensitivity responses which do not cause most epidermal keratinocytes to express HLA-DR.

Detection and quantitation of HLA class II molecules on keratinocytes by quantitative immunofluorescence

The paper describes measurements of HLA-DR antigen expression on normal human keratinocytes in culture using anti-HLA-DR antibodies and fluorescent Protein A or fluorescent second antibody methods and a low-light level video camera and image analysis program to quantitate the fluorescence output. The measurements are ultimately quantitated in terms of molecules of Ia antigen reacting material per cell. The method has a sensitivity at a S/N ratio of 10:1 of 180 molecules/micron2. The results show that normal keratinocytes do indeed express class II antigens on their surfaces at levels well above background. We confirm that treatment of the cells with gamma-interferon produces enhanced expression of DR antigens within 4 days. The method of quantitation is applicable to fluorescence and other low light level images.

Interferon-gamma activates co-ordinate transcription of HLA-DR, DQ, and DP genes in cultured keratinocytes and requires de novo protein synthesis

The purpose of this study was to determine the effect of interferon-gamma on keratinocyte major histocompatibility complex class II gene transcription. Transformed human foreskin keratinocytes (SVK14 cells) were incubated with recombinant IFN-gamma in the presence or absence of the protein synthesis inhibitor cycloheximide. Total cellular RNA was extracted from the cells and Northern blot analysis carried out using cDNA probes for all the functional class II genes. We report that 1) there is co-ordinate activation of all the class-II genes; 2) the rate of transcription varies between gene loci after activation; and 3) de novo protein synthesis is required for IFN-gamma activation of class II transcription.

Human endometrial epithelial cell lines for studying steroid and cytokine actions

Recent studies suggest that the proliferation and expression of HLA-DR molecules in endometrial epithelium may be regulated by systemic steroids and local cytokines. To test the interacting influences of cytokines and steroids on the expression of HLA-DR and proliferation of epithelial cells, an endometrial cell model is required that is sensitive to both signals. In this study, we characterize cells of carcinoma cell lines of endometrial lineage for their responsiveness to cytokines and steroids. Independently developed for its response to steroid hormones from a well-differentiated adenocarcinoma of human endometrium, EnCa101AE cell line is further cloned for the expression of progesterone receptor. Immunohistochemical localization using monoclonal antibodies demonstrates that both EnCa101AE cell line and cloned ECC1 cells are purely epithelial, as evidenced by the expression of cytokeratin and epithelial membrane antigen, express estrogen receptors, and concomitantly exhibit IFN-gamma receptor. Experiments using radioiodinated IL-1 reveal that these cell lines also possess high affinity receptors for IL-1. As indicated by the induction of HLA-DR molecules, and alterations in morphologic characteristics, these cell lines are sensitive to both IFN-gamma and IL-1 action. The class II molecules (HLA-DR, HLA-DP, and HLA-DQ) are differentially induced by IFN-gamma treatment in carcinoma cell lines, with HLA-DR being the prevailing induced molecule. IFN-gamma inhibits and estradiol-17 beta promotes growth of ECC1 cells in a dose- and time-dependent manner. These findings indicate that the interacting effect(s) of the cytokines and steroid hormones on endometrial epithelium may be studied in these unique steroid- and cytokine-sensitive epithelial cell lines.

Kinetics of class II MHC expression on cytotoxic T cells generated by skin allograft

In the present work the kinetics of class II MHC expression on OX8+ lymphocytes generated by skin allograft and its relationship to the lytic activity were studied. Mononuclear cells from the spleen of LEW (RT1(1) rats bearing BN (RT1n) skin graft for 3, 5 or 7 days were sorted out by sequential immune affinity using columns of Degalan-V26 beads treated with anti-rat or anti-mouse Ig. After depletion of B cells, T cells were precoated with W3/25 MoAb (anti-CD4 equivalent) and sorted out using an anti-mouse Ig column. The W3/25-/OX8+ cells (CD8 equivalent) were then coated with OX4 MoAb (anti-RT1.B) or murine A.TH anti-A.TL alloantiserum (anti I-E, cross-reacts with RT1.D) and were passed through a new anti-mouse Ig column in order to obtain the four subpopulations, RT1.B+, .B-, .D+ and .D-. Their specific lytic activity against BN Con A-stimulated cells increased from the 3rd to the 7th d after the skin graft. The lytic activity observed on the 3rd and 5th d was associated with all four subpopulations analyzed. In contrast, on the 7th d, the lytic activity was concentrated in the RT1.B+ subpopulation. These results, associated with the increase in the number of OX8+/RT1.B+ cells along with days after graft, suggest that RT1.B expression is not essential but is associated with the effectiveness of the cytotoxic activity. It is also possible that RT1.B expression is a marker of cytotoxic T-cell differentiation.

Differential enhancement of interferon-gamma-induced MHC class II expression of HEp-2 cells by 1,25-dihydroxyvitamin D3

Interferon-gamma (IFN-gamma) induces the expression of MHC class II antigens on non-lymphoid cells. In this study we investigated the effect of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), the most active metabolite of vitamin D3, on the IFN-gamma-induced expression of MHC class II antigens on HEp-2 cells. We found that 1,25(OH)2D3 enhanced the IFN-gamma-induced expression of HLA-DR on these cells. Differential effects on the MHC class II antigens HLA-DR, -DQ and -DP were also observed.

Expression of MHC class II antigens and immunoglobulin M by the corneal epithelial cells in herpetic keratitis

The corneal buttons obtained from 4 patients with active epithelial and stromal herpetic keratitis were studied with routine microscopy and immunohistochemistry. We used an immunoperoxidase technique with monoclonal antibodies directed against Langerhans cells, lymphocyte subsets, MHC products and immunoglobulins A, G, M and D. The epithelium and stroma contained an inflammatory infiltrate composed of polymorpho-nuclear leukocytes, dendritic cells, B-lymphocytes and T-lymphocytes (helper/inducer and suppressor/cytotoxic subsets). The epithelial cells of all the corneal buttons expressed MHC class II antigens. IgM was bound to the membrane of the epithelial cells in 3 specimens. HSV antigenic material was localized in the epithelial cells and in the stromal keratocytes by a direct immunofluorescence technique. Our data suggest that cell-mediated as well as antibody-mediated immune responses are involved, with a possible role for an autoimmune mechanism in the pathogenesis of this condition.

Effect of gamma-interferon on lectin-binding glycoproteins in cultured human keratinocytes

We report the effect of exposure of human keratinocyte cultures to human recombinant gamma-interferon (g-IFN) on the expression of glycoproteins. Concanavalia ensiformis agglutinin (Con-A), and Arachis hypogaea agglutinin (PNA) were used to investigate expression of glycoproteins. NP-40 extracts from cultures grown with or without 100 U/ml g-IFN were analyzed by incubation of SDS-polyacrylamide gels with 125I-labeled lectins. Comparison of Con-A binding glycoprotein profiles showed both qualitative and quantitative changes related to the effect of g-IFN. Differences were also apparent after labeling of the gels with PNA. A limited number of components were labeled, with most of the reactivity falling within a couple of diffuse bands with high molecular weight (300 to 360 kDa). These components were strongly labeled in extracts from cells grown in the presence of g-IFN, but weakly reactive in control cultures. Neuraminidase treatment unmasked a 205 kDa PNA binding molecule only when cells were cultured in the absence of g-IFN. These changes are interpreted in terms of increased keratinocyte differentiation induced by g-IFN and demonstrate that glycoproteins bearing carbohydrate residues available to lectins Con-A and PNA have to be taken into account to better understand the complex action of this lymphokine. In inflammatory lesions, such changes in the glycoproteins of keratinocytes expressing HLA-DR antigens remain to be explored.

Alterations induced in normal human skin by in vivo interferon-gamma

In a study of the direct effects of interferon-gamma (IFN-gamma) on normal human skin, healthy adult male volunteers received either 3 micrograms (n = 4) or 30 micrograms (n = 9) of recombinant IFN-gamma administered intradermally over 3 days. Biopsies were taken on day 6 and histopathological examination of fixed paraffin-embedded sections from sites which had received 30 micrograms IFN-gamma revealed a moderate perivascular lymphohistiocytic dermal infiltrate with mast cells. Immunophenotyping of 5 microns cryostat sections demonstrated that 3 micrograms IFN-gamma induced keratinocyte HLA-DR expression in the absence of any significant infiltrate. More intense keratinocyte HLA-DR expression was produced by 30 micrograms IFN-gamma in all specimens, with HLA-DP concurrently expressed in three biopsies. The ratio of CD4:CD8 cells within the infiltrate was approximately 3:1. CD1 + cells within the epidermis were markedly depleted by 30 micrograms IFN-gamma, while CD1-labelled cells were observed in the dermal perivascular infiltrate. Intradermal IFN-gamma induces similar immunopathological changes to those observed in many of the inflammatory dermatoses.