Cell-mediated immunity in cutaneous disease

Mechanisms of drug eruptions: Part I

The pathogenetic mechanisms underlying common, and less common but severe, adverse cutaneous drug reactions are reviewed. Pharmacogenetic variability may account for a susceptibility to serious drug reactions to sulphonamides and anticonvulsants, as well as to lupus erythematosus (LE)-like syndrome. Exanthematous drug reactions may have an immunological basis. Cell mediated cutaneous drug reactions, including lichenoid reactions, LE-like syndrome, fixed drug eruption, erythema multiforme, Stevens-Johnson syndrome and toxic epidermal necrolysis, will inevitably involve elements of the skin immune system. Graft-versus-host disease provides a useful model for aspects of these drug-induced disorders. Urticaria, angioedema, anaphylaxis and anaphylactoid reactions may involve Type I immunoglobulin (Ig)-mediated or Type III hypersensitivity, or may be caused by pharmacological, non-allergic means. Drug-induced vasculitis, serum sickness and the Arthus phenomenon are manifestations of the immune complex disease. Drug-induced pemphigus may involve immune dysregulation, but several thiol-containing drugs are able to cause antibody-independent acantholysis directly.

Human keratinocytes activate primed major and minor histocompatibility antigen specific Th cells in vitro

Keratinocytes are activated to express MHC class II and ICAM-1 molecules during cutaneous inflammatory reactions. It is controversial how the interaction between these 'nonprofessional' antigen presenting cells (APC) and infiltrating T cells affects the local inflammatory response. To address this issue we analyzed whether IFN gamma-treated cultured human keratinocytes would activate established Th cell clones in vitro. Three allo DR specific T cell clones were induced to proliferate in a HLA-DR and LFA-1/ICAM-1 dependent fashion upon coculture with intact layers of IFN gamma stimulated keratinocytes. Likewise, keratinocytes also could activate two out of four minor histocompatibility (mH) antigen specific Th cell clones obtained from peripheral blood leukocytes (PBL) of graft versus host disease patients. The T cell activating potential of MHC class II+ keratinocytes was shown to be relatively low compared to specialized APC as PMNC and EBV-BLCL. Most strikingly, measurable allo MHC and mH antigen specific Th cell proliferation was only induced by using adherent keratinocytes at low cell densities, but not by keratinocytes in suspension. The results presented here indicate that in vitro conditions may crucially influence observations regarding the T cell activating potential of MHC class II expressing keratinocytes. Furthermore, our results indicate that, in addition to a tolerizing effect as suggested by previous reports, interaction of primed antigen specific T cells with activated keratinocytes may also result in enhancement of a cutaneous immune response in vivo.

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.

Delayed type hypersensitivity is abnormal in patients with lichen planus

Lichen planus is characterized by the histological features of a cell-mediated attack on the epidermis. To see whether there is any defect in cutaneous immunity in non-lesional skin, we measured the response to a contact sensitizer in 17 patients with lichen planus and 27 control subjects. Sensitization was induced with 30 micrograms dinitrochlorobenzene applied to the thigh. The subjects were challenged 4 weeks later with three doses of dinitrochlorobenzene (8.8, 12.5 and 17.7 micrograms), and responses were quantified with calipers as the change in skinfold thickness at 48 h. Patients with lichen planus were significantly less responsive with smaller reactions at all challenge doses. These abnormalities suggest that the skin is abnormal in areas unaffected by the rash, and raise the possibility that there may be a primary defect in the cutaneous immune system in lichen planus.

T lymphocyte adhesion to human synovial fibroblasts. Role of cytokines and the interaction between intercellular adhesion molecule 1 and CD11a/CD18

We studied the adhesion of human peripheral blood T lymphocytes to human synovial fibroblasts stimulated with interferon-gamma (IFN gamma), tumor necrosis factor alpha (TNF alpha), interleukin-1 beta (IL-1 beta), or combinations of these cytokines. T lymphocytes bound poorly to untreated human synovial fibroblasts. IFN gamma treatment resulted in the largest increase in adhesion, followed by TNF alpha and IL-1 beta. Combinations of IFN gamma + TNF alpha and IFN gamma + IL-1 beta had a synergistic effect on intercellular adhesion molecule 1 (ICAM-1) expression and adhesion. The increase in cellular adhesion induced by cytokines correlated with the up-regulation of the number of cells expressing ICAM-1 and the density of antigen/cell. There was no synergistic effect on leukocyte function-associated antigen 3 (LFA-3) or on HLA class I or class II antigen expression. Adhesion was only partially inhibited by anti-ICAM-1, anti-LFA-1, or anti-CD18. These findings suggest the existence of ICAM-1--independent and CD11/CD18-independent adhesion mechanisms. Anti-LFA-3 was completely ineffective as an inhibitor of adhesion. There was no additive or synergistic advantage of using combinations of antibodies to increase the level of inhibition, i.e., anti--ICAM-1 + anti-LFA-3, anti-ICAM-1 + anti-CD18, or anti-ICAM-1 + anti-LFA-1 (CD11a). Our data indicate that proinflammatory cytokines may play a prominent role in the formation and exacerbation of synovial hyperplasia, by regulating the recruitment and retention of T lymphocytes via the up-regulation of adhesion molecules on synovial fibroblasts.

Counts of S-100 positive epidermal dendritic cells in Kveim test skin biopsies

S-100 positive epidermal dendritic cells were counted in skin biopsies from 48 Kveim tests and four known foreign-body reactions. Counts in histologically positive Kveim biopsies (mean 11.3 per 200 basal cells) were significantly higher than in either negative biopsies (5.1; P less than 0.001) or foreign-body reactions (4.7; P less than 0.05). A similar difference was found, irrespective of the histological appearances, between biopsies from patients diagnosed clinically as having sarcoidosis (10.5) and those in which another diagnosis had been made (4.1; P less than 0.001). In biopsies from patients with sarcoidosis 70% had a positive Kveim test, 70% had a raised epidermal dendritic cell count and one or the other was positive in 90%. All cases in which both the Kveim test was positive and the dendritic cell count was raised had a final clinical diagnosis of sarcoidosis. Counts of S-100 positive epidermal dendritic cells are useful in differentiating positive reactions to Kveim suspension from non-specific reactions to foreign material and increase the diagnostic confidence of the Kveim test.

The role of adhesion molecules in epithelial-T-cell interactions in thymus and skin

Interaction of T lymphocytes with other cell types is important for normal T-cell development and function. Recently, a number of adhesion molecules important in T-cell interactions with other cell types have been defined. In this paper we review the role of two adhesion pathways, CD2/LFA-3 and LFA-1/ICAM-1, in T-cell interactions with epithelial cells of the thymus and skin. While thymic epithelium-T-cell interactions were mediated by both the LFA-1/ICAM-1 pathway and the CD2/LFA-3 pathway, epidermal-T-cell interactions were mediated primarily by the LFA-1/ICAM-1 pathway. Although ICAM-1 was not expressed in vivo on epidermal keratinocytes in normal skin, ICAM-1 was expressed by epidermal keratinocytes at the site of T-cell infiltration in inflammatory dermatitis. ICAM-1 was expressed in vivo on thymic epithelium. Both LFA-3 and ICAM-1 were expressed on epithelial cells of thymus and skin early on in fetal ontogeny. These antigen-independent adhesion molecules play an important role in the cell-cell interactions associated with T-cell differentiation and function.

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).

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.

Microvascular endothelial cell culture

Microvascular endothelial cells play a central role in inflammation, tumor metastasis, and wound healing. Methods to study these processes in vitro using cells isolated from adult skin, from the inner and the outer segments of the neontal foreskin, and from experimental animals are reviewed. A new modified Iscove's medium supplemented with 2% pre-partum maternal serum, dibutyryl cyclic AMP, isobutyl methylxanthine, thymidine, and hypoxanthine is described. This modified medium supports growth of both adult and neonatal endothelial cells up to seven passages with retention of cytologic markers closely identified with endothelial cells (Weibel-Palade bodies, Factor VIII-associated antigen). Several functions associated with the microvasculature in situ are expressed by microvascular endothelial cells in cell culture. Such functions include the formation of a basement membrane, angiogenesis, intercelluar gap formation in response to vasoactive agents, and the attachment and migration of lymphocytes through endothelial monolayers.

Flow cytometric analysis and sorting of HLA-DR+CD1+ Langerhans cells

There is a considerable need for reliable methods for enumeration and enrichment of Langerhans cells (LCs), since they continue to be the subject of intensive investigation in normal and diseased skin. It has been claimed that standard labelling with either anti-HLA-DR or OKT6 antibodies alone may fail to identify potentially important subsets of LCs with the phenotypes HLA-DR+CD1- and HLA-DR-CD1+. We report here on flow cytometric analysis of suction blister-derived normal epidermal cell (EC) suspensions, double stained with phycoerythrin-conjugated anti-HLA-DR and fluoresceinated OKT6. In seven separate experiments, no evidence for the existence of either HLA-DR+CDI- or HLA-DR-CDI+ ECs was obtained. We found that HLA-DR+CDI+LCs, which constituted a mean of 2.5% (+/- 0.3 SEM) of all ECs, could be readily identified on the basis of fluorescence, and that their light scatter characteristics were those of moderately sized cells of low granularity. We further describe our method for flow cytometric enrichment of such HLA-DR+CDi+ LCs for functional studies, based on selection on both fluorescence and light scatter criteria. Enrichment is to greater than 90% purity, and the method is applicable to the small number of ECs (approximately 1 x 10(6] obtained from a suction blister.

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)

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

Lymphocytes bind to cultured keratinocytes that are treated with interferon gamma (IFN-gamma) and tumor necrosis factor (TNF). When the lymphocytes are preincubated with antibody to lymphocyte function associated antigen-1 (LFA-1), this adherence is inhibited. Because intercellular adhesion molecule-1 (ICAM-1) is a ligand for LFA-1, we studied the cellular expression of ICAM-1, as well as two other IFN-gamma-inducible antigens, (HLA) human lymphocyte antigens DR and DQ, in both normal and diseased skin. The modulation of these cell surface antigens by IFN-gamma and TNF with the use of short-term organ cultures of skin was compared with isolated keratinocytes grown in a conventional tissue culture system. While in normal skin, keratinocytes did not express HLA-DR, DQ, or ICAM-1, when organ cultures were supplemented with IFN-gamma, rapid induction of keratinocyte ICAM-1 expression occurred after 24 hours; HLA-DR but not DQ expression occurred after 48 hours. TNF also induced keratinocyte ICAM-1 expression (although to a lesser degree than IFN-gamma) but did not induce either keratinocyte HLA-DR or DQ expression. There was good correlation of keratinocyte expression of ICAM-1 and HLA-DR by IFN-gamma and TNF when the epidermis of the organ culture system was compared with the isolated keratinocytes grown in tissue culture. The presence of intraepidermal lymphocytes correlated extremely well with keratinocyte ICAM-1 expression but not with keratinocyte HLA-DR expression in psoriasis, atopic dermatitis, lichen planus, and mycosis fungoides. The intensity of endothelial cell expression of ICAM-1 correlated with the degree of dermal inflammation. We conclude that IFN-gamma, once produced by activated T lymphocytes in the dermis, may be of importance in lymphocyte trafficking in the epidermis by the induction of keratinocyte ICAM-1 expression. The use of the short-term organ culture system, in which there is inducible ICAM-1 expression, provides an experimental bridge between purely in vitro and in vivo investigations to further our understanding of the molecular basis for lymphocyte apposition to keratinocytes in the skin.

PUVA therapy decreases HLA-DR+ CDIa+ Langerhans cells and epidermal cell antigen-presenting capacity in human skin, but flow cytometrically-sorted residual HLA-DR+ CDIa+ Langerhans cells exhibit normal alloantigen-presenting function

We have investigated the effects of PUVA therapy on human Langerhans cell (LC) immunophenotype and function. Epidermal sheets were obtained from exposed, and control shielded, forearm skin at the end of a course of PUVA therapy, in patients receiving treatment routinely for a variety of dermatoses. PUVA therapy decreased the overall number of HLA-DR+CDIa+ LCs in epidermal sheets, and in epidermal cell (EC) suspensions examined using a fluorescence activated cell sorter (FACS). PUVA therapy also reduced the overall EC allostimulatory capacity in the allogeneic epidermal cell-lymphocyte reaction (ELR), and the capacity of ECs to present tetanus toxoid to, and augment concanavalin A-mediated stimulation of, lymphocytes in the autologous ELR. Depressed allostimulation by ECs from PUVA-treated skin could not be restored by indomethacin (added to block prostaglandin synthesis). The reductions in LC numbers and EC allostimulatory capacity varied according to dose, and time since cessation, of PUVA therapy, and in individual patients were of comparable degree. By contrast, the allostimulatory capacity of residual LCs from PUVA-treated skin (purified using the FACS) did not differ from that of purified control LCs. PUVA-induced suppression of cutaneous immune responses, therefore, results at least in part from an overall impairment of EC antigen-presenting capacity. Residual HLA-DR+CDIa+ LCs in PUVA-treated skin which retain their alloantigen-presenting function may represent a subgroup of PUVA-resistant LCs; alternatively, these cells may be as yet unaffected because they have only recently migrated into the epidermis.

Flow cytometrically-sorted residual HLA-DR+T6+ Langerhans cells in topical steroid-treated human skin express normal amounts of HLA-DR and CD1a/T6 antigens and exhibit normal alloantigen-presenting capacity

Topical corticosteroids decrease the number of HLA-DR+T6+ Langerhans cells (LCs) and the antigen-presenting capacity of epidermal cells (ECs). We have investigated the properties of residual HLA-DR+T6+ LCs in steroid-treated human skin. Flow cytometric analysis revealed that clobetasol propionate 0.05% applied twice daily for 7 d reduced the percentage of HLA-DR+T6+ LCs in EC suspensions to 46% of control (from a mean percentage +/- sem of 2.49 +/- 0.30 in control skin to 1.15 +/- 0.22 in steroid-treated skin), but did not significantly alter the relative amounts of HLA-DR and CD1a/T6 antigens per individual HLA-DR+T6+ cell. HLA-DR+T6- and HLA-DR-T6+ cells were not detected in either group. Steroid therapy significantly decreased the allostimulatory capacity of unsorted ECs. By contrast, in parallel experiments in which the same EC suspensions were greatly enriched (85% to 90%) for HLA-DR+T6+ LCs by flow cytometric sorting, the allostimulatory capacity of purified LCs from steroid-treated skin was not significantly different from control. Residual HLA-DR+T6+ LCs, which preserve their antigenic markers and alloantigen-presenting function, may be relatively unaffected because they have only recently immigrated into the epidermis, or they may represent a subgroup of steroid-resistant LCs. Alternatively, given the dose response relationship between topical steroid potency and decrease in HLA-DR+T6+ LC numbers, the apparent steroid resistance of residual HLA-DR+T6+ LCs may reflect heterogenity in the density of expression of LC steroid receptors.

Biology and molecular biology of epidermal cell-derived thymocyte activating factor

ETAF/IL-1 has a multiplicity of divergent biological effects: enhancement of thymocyte proliferation, stimulation of cells in the hypothalamus to mediate fever, leukocyte chemotaxis, stimulation of hepatic synthesis of acute-phase proteins, augmentation of IL-2 production and keratinocyte proliferation. Until recently, it has not been possible to determine whether these divergent activities are mediated by closely related cytokines or separate cytokines. Now with the identification of IL-1 alpha, IL-1 beta and IL-1k from keratinocytes, these studies will become possible. In either case, it is likely that ETAF/IL-1 plays an important role in local cutaneous and systemic inflammatory and immunological events.

Lymphocyte adhesion to psoriatic dermal endothelium is mediated by a tissue-specific receptor/ligand interaction

Dermal lymphocytic infiltrates are characteristic of psoriasis and may be involved in the pathogenesis of the disease. We have utilized an in vitro lymphocyte adherence assay to examine the mechanism(s) mediating lymphocyte migration into psoriatic skin. In this assay, we assessed the binding of lymphocytes overlaid onto frozen biopsy sections of normal and psoriatic skin. Lymphocytes isolated from human blood and rat thoracic duct bound specifically to dermal endothelia in psoriatic plaques but not to those of uninvolved skin from psoriatic patients or skin from normal individuals; analysis of the binding properties of B cells and T lymphocyte subsets revealed a preferential binding of CD4+ T cells compared with CD8+ T cells or B cells. This lymphocyte-endothelial interaction is an energy- and calcium-dependent process and involves surface protein and carbohydrate moieties, requirements similar to those found in lymphocyte interaction with post-capillary high endothelial venules (HEV) in lymphoid tissues. However, preincubation of lymphocytes with antibodies directed against surface molecules mediating adhesion to HEV of peripheral lymph node and gut-associated lymphoid tissue did not interfere with the capacity of lymphophocytes to bind to the skin. The results of this study support the hypothesis that emigration of lymphocytes from vasculature into psoriatic skin is promoted by the presence of specialized endothelia in psoriatic dermis capable of mediating specific lymphocyte-endothelial interactions.

Langerhans' cells and subtypes of human papillomavirus in cervical intraepithelial neoplasia

There is strong circumstantial evidence that human papillomavirus is a cofactor in the development of cervical neoplasia. Systemic immunosuppression has also been implicated. A study was therefore carried out examining the relation between subtypes of human papillomavirus and local immunocompetent cells in the cervix. Colposcopically directed punch biopsy specimens were taken from normal cervix and from histologically proved cervical intraepithelial neoplasia for immunohistochemical studies. Human papillomavirus genome probing was performed on the abnormal specimens. A relation was apparent between decreased Langerhans' cells and moderate to high copy numbers of human papillomavirus type 16. The reduction in Langerhans' cells was significant for human papillomavirus type 18 even at low copy numbers. Conversely, the absence of human papillomavirus was associated with increased numbers of Langerhans' cells in cervical intraepithelial neoplasia. These findings suggest that the proposed oncogenic potential of human papillomavirus type 16 and human papillomavirus type 18 in particular may be mediated by a specific effect on the afferent limb of the immune response.

Cellular autoimmunity in psoriasis and lichen planus

The objective of this investigation was to determine whether specific cellular recognition of the epidermis is associated with the human skin diseases, psoriasis and lichen planus. Epidermal cells (EC) obtained from biopsies of involved and uninvolved skin of patients with these diseases were used as stimulators and targets for autologous peripheral blood mononuclear cells (PBMC) in assays of three conventional manifestations of cellular immunity: lymphocyte transformation, leukocyte migration-inhibition and cell-mediated cytotoxicity. Parallel tests were conducted with autologous PBMC as stimulators to ascertain the tissue specificity of the reactions evoked by autologous EC. Similar assays were conducted with EC and PBMC from a large group of normal subjects, and the results were compared to those of the dermatology patients by rigorous statistical analyses. No evidence of lymphocyte-mediated cytotoxicity towards autologous EC was obtained with any of the subject groups, but autologous EC, and to a lesser extent PBMC, of the psoriasis patients, but not of the other two groups, evoked significant lymphocyte transformation. These results were obtained only with patients on Goeckerman therapy, raising the possibility that they were a manifestation of the treatment (topical coal-tar and ultraviolet light irradiation) rather than of the disease, although reasons are presented why this is unlikely. Clearer evidence of disease-associated autoimmunity was obtained in the leukocyte migration-inhibition assays, where autologous EC, and to a lesser extent, PBMC, of the psoriasis patients in general, not just those on Goeckerman therapy, and not those of the lichen planus patients or of the normal subjects, stimulated the release of a leukocyte migration-inhibition factor. These results support the concept of a central role for T-cell mediated autoimmunity in the pathogenesis of psoriasis.

Effects of topical corticosteroid therapy on Langerhans cell antigen presenting function in human skin

We have investigated the mechanisms by which topical corticosteroids modulate cutaneous immune reactions in man. Volunteers applied clobetasone butyrate 0.05% (Eumovate; EV), betamethasone valerate 0.1% (Betnovate; BV), clobetasol propionate 0.05% (Dermovate; DV), and control vehicles twice daily to forearm skin for 7 days. Steroid therapy significantly decreased the number of HLA-DR/T6 (CD1a) positive Langerhans cells (LCs) per mm2 in suction blister-derived epidermal sheets, expressed as a mean percentage of controls, as follows: EV 69.2%; BV 67.3%; DV 37.8%. LC antigen presenting capacity was determined in the allogeneic and autologous epidermal cell-lymphocyte reactions. The LC-dependent allostimulatory capacity of epidermal cells, expressed as a mean percentage of controls, was also significantly reduced by steroid therapy: EV 45.1%; BV 41.9%; DV 23.4%. Following therapy with clobetasol propionate 0.05%, the capacity of epidermal cells to present tetanus toxoid to, and to augment concanavalin A mediated lymphocyte stimulation of, autologous lymphocytes was reduced to 33.6% and 19.7% respectively of controls. Depression of epidermal cell allostimulatory capacity was not the result of a steroid-induced decrease in the production of epidermal cell-derived thymocyte activating factor (ETAF)/interleukin 1 by keratinocytes, since it could not be reversed by addition of exogenous interleukin 1. Indomethacin, added to block any potential prostaglandin synthesis during the culture period, did not restore the allostimulatory capacity of epidermal cells from steroid-treated sites. Addition of epidermal cells from DV-treated sites depressed the capacity of control epidermal cells to stimulate lymphocytes in the allogeneic epidermal-lymphocyte reaction. Our results demonstrate that the anti-inflammatory action of topical corticosteroids in man is associated not only with a reduction in the number of HLA-DR/T6 positive LCs, but also with a marked decrease in Langerhans cell-dependent T lymphocyte activation. The effects of the different steroids on both of these parameters correlated with their potency as determined in the standard occlusive vasoconstrictor assay. Topical corticosteroids are widely used for the treatment of inflammatory skin disorders, and inhibit not only the elicitation phase, but also the induction phase, of allergic contact dermatitis reactions.(ABSTRACT TRUNCATED AT 400 WORDS)

Histological features of skin and rectal biopsy specimens after autologous and allogeneic bone marrow transplantation

The histological appearances of skin and rectal biopsy specimens were studied in 31 bone marrow transplant recipients (13 autologous, 18 allogeneic) before transplant, at 28 days, at six months, and as soon as graft versus host disease (GVHD) was clinically suspected. Grades I and II skin changes were commonly seen in patients before transplant and in the autologous group after transplant, as well as in most of the allogeneic recipients with suspected GVHD. Epidermal lymphocytic infiltration was seen only in allogeneic recipients, with clinical GVHD following transplant, but this was not a consistent finding and no other histological features were seen which would distinguish early GVHD from changes caused by cytotoxic agents. Rectal biopsy specimens, however, were normal in patients before transplant and in autologous recipients at 28 days; single cell necrosis of crypt cells was seen only in six of 13 allogeneic recipients studied after transplant with clinical skin GVHD but no gastrointestinal symptoms. Skin changes greater than I and II are required for the histological diagnosis of GVHD. Rectal changes are more specific and may be present despite a lack of intestinal symptoms.

Preferential binding of monocytes and Leu 2+ T lymphocytes to interferon-gamma treated cultured skin endothelial cells and keratinocytes

Recombinant gamma interferon (r-IFN-gamma) increases the adherence of peripheral blood mononuclear leukocytes (PBMLs) to cultured keratinocytes and cutaneous microvascular endothelial cells (MECs). To determine which specific type of PBMLs bound to these r-IFN-gamma treated cells, we performed immunophenotyping on the adherent PBMLs. The adherent PBMLs were detached from the r-IFN-gamma treated keratinocytes and MECs by adding EDTA, and collected by cytocentrifugation, followed by immunocytochemical staining using a panel of monoclonal antibodies. Our results reveal that the relative adherent population of PBMLs was composed of approximately 60%-70% monocytes and 18%-24% Leu 2+ T lymphocytes (T-cytotoxic/suppressor) which preferentially bound to r-IFN-gamma treated keratinocytes and MECs. There was some lesser binding by Leu 3 + lymphocytes (T-helper/inducer); approximately 8%, and no binding of B lymphocytes. Since r-IFN-gamma also induced HLA-DR expression in keratinocytes and MECs, these in vitro data suggest that r-IFN-gamma may play an important role in the immunobiology of diverse skin diseases such as graft vs host disease, lichen planus, and other inflammatory dermatoses, because the keratinocytes express HLA-DR and the predominant T-cell subset in the epidermis is Leu 2 + (over the Leu 3 + T cell) in all of these conditions. These results represent a direct attempt to explain in situ immunophenotypic mononuclear leukocyte subset distribution patterns by using r-IFN-gamma and purified cultured cells such as keratinocytes and MECs. We propose that IFN-gamma, by both increasing the adherence of PBMLs, and promoting selective binding of monocytes and Leu 2 + T lymphocytes to both keratinocytes and MECs, may be important in regulating PBML localization and recirculation in the skin.

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

Because keratinocytes (KCs) express HLA-DR in a wide variety of skin diseases in which mononuclear leukocytes are observed in close apposition to KCs (i.e., graft-versus-host disease), and since gamma interferon (IFN-gamma) induces HLA-DR expression on KCs, we asked whether IFN-gamma treatment of KCs would influence the adherence of mononuclear leukocytes. When allogeneic peripheral blood mononuclear leukocytes (PBML) and a Leu-3+ T cell clone were coincubated with IFN-gamma-treated KCs (300 U/ml, 3 days), there was a marked increase in binding compared with nontreated KCs. Similar binding results were obtained using a cutaneous squamous carcinoma cell line (SCL-1) after IFN-gamma treatment. The IFN effect was relatively specific for IFN-gamma, as neither IFN-alpha nor -beta had any effect. Tumor necrosis factor exposure (500 U/ml, 3 days) increased the binding of the Leu-3+ T cell clone to both KCs and SCL-1 cells. Neutrophils displayed a less marked (but statistically significant) increase in binding to IFN-gamma-treated KCs. Using the Leu-3+ cell clone and SCL-1 cells, detailed kinetic analysis of the effect of IFN-gamma on binding was performed. The increased adherence between the cells began to appear after only 7 hours of treatment with r-IFN-gamma (300 U/ml) and reached a plateau at 48 hours, with significantly enhanced binding continuing for at least 48 hours after removal of IFN-gamma. The mechanism of binding was explored by preincubation of the PBML/Leu-3+ T cells with anti-LFA-1 (lymphocyte function-associated antigen) antibody (0.6-6.0 micrograms/ml), which totally inhibited the binding with no effect by anti-LFA-2 or -3 or class I or II antibodies despite documented binding of these antibodies to the cells. These results suggest that, after exposure to IFN-gamma, the ability of KCs to bind mononuclear leukocytes is strongly enhanced, and this adherence may be important in leukocyte trafficking in the skin as well as contributing to altered KC-leukocyte interaction, which may be of fundamental importance in a variety of skin disease.

Interleukin-2 stimulates resting human T lymphocytes' response to allogeneic, gamma interferon-treated keratinocytes

In order to investigate the biologic significance of HLA-DR expression by human keratinocytes, we have examined the possibility that DR-positive keratinocytes become alloantigen presenting cells for resting T cells in the presence of interleukin-2. Using this system, gamma interferon-treated, DR-positive keratinocytes stimulate the proliferation of allogeneic, resting T cells approximately 3-fold whereas non-gamma interferon-treated, DR-negative keratinocytes do not. Because a monoclonal antibody against recombinant gamma interferon inhibits this proliferation, the stimulation is dependent on pre-incubation with gamma interferon. By contrast, since the stimulation is not inhibited by a monoclonal antibody against HLA-DR, it is not clear that the stimulation is due to class II antigen expression by keratinocytes. To rule out that gamma interferon increases the expression of class I antigens, leading to stimulation of resting T cells on that basis, we determined whether gamma interferon treatment enhances class I antigen expression by keratinocytes. The lymphokine treated cells did not demonstrate more class I antigen expression than untreated keratinocytes. Thus, the observed stimulation of allogeneic, resting T cells by gamma interferon-treated keratinocytes in the presence of IL-2 is not due to increased class I antigen expression but is due to other cell surface antigen(s) induced by recombinant gamma interferon treatment. These results suggest that gamma interferon-exposed keratinocytes in the presence of interleukin-2 may augment the activation of resting T lymphocytes and, in this manner, may contribute to cutaneous inflammation.

Immunologic aspects of acute cutaneous graft-versus-host disease: decreased density and antigen-presenting function of Ia+ Langerhans cells and absent antigen-presenting capacity of Ia+ keratinocytes

Cutaneous graft-versus-host disease (GVHD) provides a unique model for studying the pathogenesis of several important lymphocyte-mediated skin diseases. Morphologic studies have suggested that Ia antigen (Ia)-bearing epidermal Langerhans cells (LC) may be specific targets for destruction in these conditions. Keratinocytes synthesize and express Ia in GVHD and some other lymphocyte-mediated skin disorders; Ia+ keratinocytes, constitutively able to secrete epidermal cell-derived thymocyte activating factor (ETAF)/interleukin 1, may possess antigen-presenting capacity, thus leading to enhanced cutaneous immune responses and disease chronicity. We therefore investigated the fate of Ia+ LC, and the potential antigen-presenting capacity of Ia+ keratinocytes, in a murine model of GVHD. Lethally irradiated C3H/He (H-2k) mice developed acute cutaneous GVHD, and expressed keratinocyte Iak, 8 days after injection of BALB/c (H-2d) bone marrow and spleen cells. Immunofluorescence studies showed a progressive decrease in the density of Ia+ epidermal LC during the evolution of GVHD. This decrease was paralleled by a progressive reduction in the allostimulatory capacity of GVHD epidermal cells (EC) in the allogeneic EC-lymphocyte reaction (ELR). The fall in the density of Ia+ LC, and in EC allostimulatory capacity in both primary and secondary ELRs, was consistently greater in GVHD mice than in mice treated only with x-irradiation. The allostimulatory capacity of GVHD and x-irradiated EC could not be restored by addition of indomethacin or exogenous ETAF to ELR cultures. The decreased allostimulatory capacity was not the result of inhibition of the ELR, since EC from GVHD and x-irradiated mice did not cause suppression when added to control ELR cultures. The capacity of EC to present ovalbumin, purified protein derivative of tuberculin, 2,4,6-trinitrobenzenesulfonic acid coupled to EC, and native cytochrome c (CYTc) to antigen-specific T-cell lines, clones, or hybridomas was reduced in x-irradiated mice and markedly decreased in GVHD mice. The capacity of EC from x-irradiated and GVHD mice to present CYTc fragment 81-104, which does not require further processing or catabolism by accessory cells, was similarly decreased. Taken together, the results indicate that: the function of LC is markedly and progressively impaired in acute GVHD; LC function is also decreased, but to a lesser extent, following x-irradiation alone; and Ia+ keratinocytes from lethally irradiated mice undergoing GVHD do not exhibit antigen-presenting capacity.