Decreased Production of Interferon in Whole Blood Cultures Derived from Patients With Psoriasis

Patients suffering from psoriasis show many alterations with respect to their immune system as documented by in vitro test systems. In the present study we investigated the in vitro production of interferons (IFN) of leukocytes from psoriatic patients to stimulation with a variety of IFN inducers. Furthermore, the lymphoproliferative responses were tested. Whole blood cultures of 30 psoriatic patients showing moderate to severe disease activity and 21 cultures from healthy controls were stimulated with the mitogens PHA, ConA, and PWM, with PPD and Tetanus Antigen as IFN γ inducers and with C. parvum, PolyI-PolyC, and Herpes simplex virus as inducers of IFN α. Interferon activity was tested in the supernatant of 48-h cultures by using an antiviral assay. Lympho-proliferation was assayed in 5-d cultures in parallel. Psoriatic patients showed a significantly decreased IFN production to all the stimuli tested. There were no significant differences in the lymphoproliferative responses; only the response to PWM was slightly decreased. The decreased IFN production by leukocytes from psoriatic patients seems to be very remarkable since increased susceptibility to infections is not generally known in these patients

Expression of the B7/BB1 Activation Antigen and its Ligand CD28 in T-Cell-Mediated Skin Diseases

Interactions of CD28 (on T cells) with its recently identified ligand B7/BB1 (on antigen-presenting cells) have been shown to activate T cells via a major histocompatibility complex/Ag-independent “alternative” pathway, leading to an amplification of T- cell – mediated immune responses. The in vivo relevance of these molecules for cutaneous immunity is presently unknown. These findings prompted us to study the expression of B7/BB1 and CD28 in normal human skin and in selected T-cell – mediated inflammatory skin diseases. Biopsies were obtained from lesional skin of patients with allergic contact dermatitis, lichen planus, and, as control, from basal cell carcinoma and from healthy controls. Serial cryostat sections were stained with a panel of MoAbs directed against CD28, B7/BB1, CD3, CD1a, and KiM8 using immunohistochemistry (ABC technique). CD28 expression was observed in the majority of dermal and epidermal CD3+ T cells in contact dermatitis and lichen planus. In normal skin and basal cell carcinoma, CD28 was expressed only occasionally by perivascular T cells. In allergic contact dermatitis and lichen planus, B7/BB1-expression was found on dermal dendritic cells, on dermal macrophages, on Langerhans cells, focally on keratinocytes, and occasionally on dermal T cells. No B7/BB1 immunoreactivity was detected in normal skin and basal cell carcinoma. These findings indicate that T-cell – mediated skin diseases are accompanied by an influx of CD28+ T cells and an upregulation of B7/BB1 on cutaneous antigen- presenting cells, keratinocytes, and on some T cells. We speculate that “alternative” T cell-activation via the B7/CD28 pathway may contribute to the pathogenesis of these skin diseases

55-kd Tumor Necrosis Factor Receptor Is Expressed by Human Keratinocytes and Plays a Pivotal Role in Regulation of Human Keratinocyte ICAM-1 Expression

Tumor necrosis factor α (TNFα) is a potent modulator of human keratinocyte intercellular adhesion molecule-1 (ICAM-1) expression. TNFα is known to exert its biologic effects by binding to specific cell-surface receptors. Two distinct TNF binding molecules, the 55-kd and the 75-kd TNF receptor (TNFR) recently have been found to be expressed by human cells. These two receptor types are independently regulated and differ markedly in their intracellular regions, indicating functional dichotomy. In order to gain further insight into the mechanisms underlying ICAM-1 regulation in human keratinocytes, in the present study, the receptor molecules mediating TNFα induced ICAM-1 upregulation in human keratinocytes was defined. Human keratinocyte TNFR expression was assessed using monoclonal antibodies that specifically recognize the 55-kd or the 75-kd TNFR. Using FACS analysis, normal (HNK) as well as transformed (KB) human keratinocytes were found to react with anti-55-kd TNFR, but not anti-75-kd TNFR antibodies. These immunofluorescence data were confirmed by Northern blot analysis revealing clearly detectable amounts of mRNA specific for the 55-kd TNFR in KB cells. Incubation of human keratinocytes with anti-55-kd TNFR antibodies at 37°C for 24h increased ICAM-1 expression in a TNFα-like fashion. Moreover, the well known synergistic effect of IFNγ plus TNFα on keratinocyte ICAM-1 induction could be mimicked by stimulation of cells with IFNγ plus anti-55-kd TNFR antibodies. Synergistic ICAM-1 induction was not associated with increased expression of the 55-kd TNFR in IFNγ-stimulated human keratinocytes. These studies indicate that human keratinocytes express the 55-kd TNF receptor and that this surface molecule may play an important role in regulation of human keratinocyte ICAM-1 expression

The Chemokine RANTES Is More than a Chemoattractant: Characterization of Its Effect on Human Eosinophil Oxidative Metabolism and Morphology in Comparison with IL-5 and GM-CSF

Eosinophils were shown to play a major role in the allergic inflammatory process leading to the clinical symptoms of atopic dermatitis. Only selected cytokines are capable of inducing a chemotactic response in eosinophils. In particular, the chemokine RANTES was recently shown to be a potent eosinophil chemotaxin. To examine the role of RANTES in eosinophil activation, we investigated the effect of RANTES and other chemokines on morphology and oxidative metabolism of highly purified eosinophils of normal nonatopic blood donors by assessment of functional as well as morphologic criteria. RANTES, and, to a lesser extent, MIP-1α significantly induced the production of reactive oxygen species by human eosinophils, whereas MCP-1, MIP-1β, and interleukin (IL)-8/NAP-1 had no significant effects. RANTES stimulated only a subpopulation of the normal eosinophils. With the exception of IL-8, none of the cytokines tested had any significant effect on polymorphonuclear neutrophilic granulocytes.. By scanning electron microscopy, RANTES induced characteristic changes that were completely abrogated in the presence of cytochalasin B. Based on functional and ultrastructural assays significant extracellular but not intracellular H2O2 production was detected and completely inhibited by cytochalasin B. Separation of eosinophils by discontinous density gradients revealed the existence of two hypodense eosinophil populations, one which showed significantly reduced responses upon stimulation with RANTES. RANTES-induced production of reactive oxygen species was almost completely inhibited by staurosporine, wortmannin, or pertussis toxin. Based on these data it is evident that RANTES represents a potent eosinophil-specific activator of oxidative metabolism. Besides its chemotactic activity on T cells and eosinophils, therefore, RANTES may be involved in the functional activation of eosinophils in the skin of patients with atopic dermatitis

Induction of Intercellular Adhesion Molecule 1 (ICAM-1) Expression in Normal Human Eosinophils by Inflammatory Cytokines

Intercellular adhesion molecule-1 (ICAM-1) functions as a ligand for lymphocyte function-associated antigen-1 (LFA-1), and thereby plays a crucial role in mediating cell-cell interactions in inflammatory reactions. Human eosinophils represent important effector cells in allergic skin diseases. To gain more insight into the capacity of eosinophils to physically interact with LFA-1-positive inflammatory leukocytes, in the present study ICAM-1 expression in eosinophils was investigated. Using fluorescence-activated cell sorter analysis, it could be shown that highly purified (⩾95%) eosinophils from peripheral blood of non-atopic individuals do not constitutively express ICAM-1 molicules. However, stimulation of eosinophil with interferon gamma (IFNγ), tumor-necrosis factor alpha (TNFα), or interleukin 3 (IL-3) markedly upregulated ICAM-1 surface expression in a time-and dose-dependent manner. Cytokine-induced ICAM-1 expression in human eosinophils was corroborated by Northern blot analysis. Accordingly, unstimulated eosinophils did not express significant amounts of ICAM-1 mRNA, but ICAM-1 mRNA expression could be markedly induced in these cells upon stimulation with IFNγ plus TNFα. The combination of TNFα with either IFNγ, IL-3, IL-5, or granulocyte/macrophage colony-stimulating factor (GM-CSF) increased ICAM-1 expression in a synergistic fashion, whereas IL-5 or GM-CSF by itself did not induce ICAM-1 expression. Cytokine-induced ICAM-1 expression was specific, because IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-7, IL-8, C5a, and platelet-activating factor did not significantly affect eosinophil ICAM-1 surface expression. In summary, these studies indicated that eosinophils may be activated to express the adhesion molecule ICAM-1 surface expression. In summary, these studies indicated that eosinophils may be activated to express the adhesion molecule ICAM-1 upon stimulation with selected inflammatory cytokines, which may allow adhesion-mediated crosstalk between eosinophils and LFA-1-positive cells. In addition, these data demonstrate for the first time a role for IL-3, IL-5, and GM-CSF in regulation of ICAM-1 expression in human cells