Platelet activating factor-induced clinical and histopathologic responses in atopic skin and their modification by the platelet activating factor antagonist BN52063

The clinical and histopathologic responses to intradermal platelet-activating factor (PAF-acether) in atopic subjects, without evidence of atopic dermatitis are documented. An immediate acute wheal and flare reaction was observed in all volunteers. Histopathologically, the reaction was characterized by a predominantly neutrophilic response, which was seen at 30 minutes and was maximal at 4 hours. Eosinophils were observed in the infiltrate as early as 30 minutes after injection, and were maximal by 12 hours. The specific PAF-acether antagonist BN52063 antagonized the acute flare response to intradermal PAF-acether but had little effect on cellular recruitment at the site of injection.

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).

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.

Marked synergism between tumor necrosis factor-alpha and interferon-gamma in regulation of keratinocyte-derived adhesion molecules and chemotactic factors

T lymphocytes and mononuclear cells preferentially accumulate in the epidermis in inflammatory skin disease. To determine the role of keratinocytes in both the chemotaxis and adhesion of these cells to the epidermis, cultured keratinocytes were incubated with IFN-gamma and tumor necrosis factor-alpha (TNF-alpha), and mRNA detected and quantitated for IL-8, monocyte chemotaxis and activating factor, and intercellular adhesion molecule-1. Whereas induction of these mRNAs was either absent, or relatively weak and transient, to either IFN-gamma or TNF-alpha alone, when administered in combination there was a dramatic increase and persistence in the induction of all three genes. Pretreatment of the keratinocytes with cycloheximide failed to eliminate transcription, implying that all three are primary response genes. Transforming growth factor-beta, which modulates other keratinocyte functions (not related to adhesion or chemotaxis of inflammatory cells) failed to induce any of the genes. These novel findings potentially explain the selective recruitment of T cells and monocytes observed in inflammatory skin disease, because IFN-gamma and TNF-alpha can co-ordinately regulate keratinocyte-derived chemoattractants and adhesion molecule production.

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.

Keratinocyte expression of OKM5 antigen in inflammatory cutaneous disease

Keratinocyte expression of the monocyte/macrophage surface antigens defined by OKM1 and OKM5 antibodies (Ortho Diagnostics) was examined using the peroxidase anti-peroxidase immunohistochemical technique. A range of inflammatory cutaneous disorders were investigated, including lichen planus, psoriasis and atopic dermatitis. Positive suprabasal keratinocyte expression of OKM5 antigen was observed in all disorders, while keratinocyte staining with OKMI antibody was consistently negative. These results provide further evidence that keratinocytes may play an important role in cutaneous immune responses. Furthermore, they are consistent with the recent observation that HLA-DR positive keratinocytes may modulate cutaneous immunological reactions by inducing T-cell unresponsiveness.

Gamma-interferon induced human keratinocyte HLA-DR synthesis: the role of dermal activated T lymphocytes

Experiments were performed to examine the hypothesis that the surface expression of HLA-DR by keratinocytes in certain disease states is conferred by the activity of gamma-interferon, derived from dermal activated T lymphocytes. In vivo studies revealed a spatial relationship between keratinocyte HLA-DR expression and activated T lymphocytes within the dermal inflammatory infiltrate. In vitro studies confirmed that gamma-interferon can induce keratinocyte synthesis of HLA-DR. These results suggest that, in vivo, gamma-interferon produced by activated T lymphocytes induces keratinocyte HLA-DR synthesis and expression.

Products of class II major histocompatibility complex gene subregions are differentially expressed on keratinocytes in cutaneous diseases

Aberrant expression of class II major histocompatibility complex (MHC) subregion antigens by keratinocytes was examined immunohistochemically in a range of cutaneous disorders. Although cell surface expression of human lymphocyte antigen (HLA)-DR was observed, HLA-DQ and HLA-DP were not expressed in any disorder investigated except for allergic contact dermatitis. Epidermal Langerhans cells expressed antigens of all three subregions on the cell surface. Differential expression of class II MHC subregion antigens may be related to tissue levels of gamma-interferon or to different functions of each subregion.

Surface-bound immunoglobulin E on antigen-presenting cells in cutaneous tissue of atopic dermatitis

Both type I and type IV hypersensitivity reactions have been implicated in the pathogenesis of atopic dermatitis. Using monoclonal antibodies we have identified IgE on the surface of cutaneous dendritic cells in both lesional and nonlesional skin. Double immunofluorescence labeling demonstrates these cells to be antigen-presenting cells. Immunoglobulin E (IgE) was not identified on such cells either in atopic individuals with no history of dermatitis or in patients with a range of other dermatoses. Further studies are consistent with IgE being bound to the cell surface via an Fc-IgE receptor. We conclude that this finding is specific for atopic dermatitis and thus may provide a link between the two types of hypersensitivity reactions frequently observed.

Epidermal class II human lymphocyte antigen expression in atopic dermatitis: a comparison with experimental allergic contact dermatitis

Epidermal patterns of class II human lymphocyte antigen (HLA) expression in atopic and allergic contact dermatitis have been compared, using monoclonal antibodies recognizing each subregion. Expression of class II human lymphocyte antigens on keratinocytes has been confirmed in allergic contact dermatitis, while we have found them to be absent in atopic dermatitis. This finding argues that cell-mediated immune responses, possibly to epicutaneous contact with allergen, are not implicated in the pathogenesis of atopic dermatitis.

Evaluation of lingual artery hemodynamics in stroke patients using Doppler ultrasound

Doppler blood flow studies were carried out on deep lingual arteries of young adults and stroke patients to see how the hemodynamics of this artery would be altered in the stroke group, who were selected on the basis of their having carotid atherosclerosis. The healthy controls exhibited a consistent and characteristic velocity pulse profile, which included a distinctive dichrotic notch and significant diastolic flow. The stroke group especially lacked these two critical parameters, and some exhibited amorphous flow patterns and cardiac arrhythmias. Implications of these findings in relationship to atherosclerosis are discussed.

Developmental behaviors: delayed appearance in monkeys asphyxiated at birth

In "Developmental behaviors: delayed appearance in monkeys asphyxiated at birth" by J. A. Sechzer et al. (19 Mar., p. 1173), the last two lines of column 1 and the first five lines of column 2, page 1175, should read "Deficits in learning and memory (10, 11) when compared with the establishment of these developmental behaviors (although significantly delayed) suggest that brain damage by neonatal asphyxia can result in a degree of dissociation..."

Development behaviors: delayed appearance in monkeys asphyxiated at birth

Developmental behaviors were studied in monkeys subjected to asphyxia at birth. Visual depth perception, visual pla ing, and locomotion appeared significantly later than in nonasphyxiated monkeys. After these behaviors had been established in asphyxiates, however, there was little difference from those observed in normal monkeys. These results were compared with reports of permanent learning deficits that occur in monkeys asphyxiated at birth for similar periods of time. Such comparison suggests that the neural structures responsible for the developmental behaviors studied are not damaged by asphyxia to the same extent as those for acquisition. Delay in development may be an early indication of brain damage with subsequent mental retardation.