Interleukin-8 plays its role at local level in psoriasis vulgaris

The pro-inflammatory properties of interleukin-8 (IL-8) suggest a major role of this peptide in inflammatory processes of skin and other organs. Both biochemical and immunohistochemical studies from our group have demonstrated IL-8 peptide within psoriatic scales and epidermis. So far, however, the relevance of circulating IL-8 and its relation to locally produced IL-8 in this disease remain unclear. Serum IL-8 levels of psoriatic patients were determined in sandwich-ELISA prior to therapy as well as during therapy. Using either the assay from our laboratory or three commercial ELISAs, no correlation was found between serum IL-8 levels and disease severity at any stage of the disease. Similarly, epidermal IL-8-immunoreactivity was monitored immunohistochemically in sequential biopsies from individual psoriatic lesions as they resolved during the course of therapy. Initially, decreased epidermal IL-8 immunoreactivity shifted to a homogeneous staining comparable to normal or non-diseased skin as lesions resolved under treatment. These results indicate a role of IL-8 at local level in psoriatic skin. In contrast to hyperinflammatory diseases like sepsis, where increased serum IL-8 levels are found, in psoriasis either circulating IL-8 is absent or potent mechanisms are operative effectively binding and/or inactivating IL-8 as it enters circulation.

RANTES production by cytokine-stimulated nasal fibroblasts: its inhibition by glucocorticoids

Nasal fibroblasts play an important role in both nasal polyposis and nasal allergic diseases and they are known to release a number of proinflammatory cytokines, including GM-CSF, IL-8 and IL-6. The aim of this present work was to investigate whether cytokine-stimulated nasal fibroblasts release biologically active RANTES as well as to study the effect of corticosteroids on the ability of nasal fibroblasts to produce the cytokine. Measurements of RANTES by ELISA demonstrated that RANTES is constitutively secreted spontaneously (21+/-4 vs. 19+/-6 ng/ml, respectively p>0.05). Stimulation of these cells with either TNF-alpha, IL-1beta or IFN-gamma induce further release of RANTES in a dose-dependent manner with TNF-alpha being the most potent stimulus. RANTES mRNA expression in nasal fibroblasts correlated with the amount of protein released in the culture supernatant upon cytokine stimulation. Moreover, chemotaxis studies demonstrated that the nasal-derived RANTES was biologically active on eosinophils. Betamethasone and hydrocortisone were found to downregulate RANTES mRNA expression in TNF-alpha-stimulated fibroblasts. These observations suggest that RANTES released by nasal fibroblasts may regulate eosinophil recruitment in nasal disease while glucocorticoids may inhibit the influx of these cells by suppressing the production of RANTES.

The CXC receptor 2 is overexpressed in psoriatic epidermis

The CXC chemokines interleukin-8 and GRO/melanoma growth-stimulatory activity (GRO-alpha) are potent activators of neutrophils and lymphocytes, but also stimulate growth and differentiation of nonhematopoietic cells like keratinocytes, fibroblasts, and melanocytes. High mRNA and protein levels have been detected in psoriatic epidermis. Chemokine activation of target cells is mediated by specific receptors and two CXC receptors have been described with similar affinity for interleukin-8 but different affinities for GRO-alpha. In this study, we examined the expression of both CXCR1 and CXCR2 in psoriatic tissue, identifying the target cells of chemokine activation in psoriasis. By immunohistochemistry and in situ hybridization, as confirmed by northern blot analysis and reverse transcriptase polymerase chain reaction, we could detect expression of the CXCR2 in suprabasal lesional psoriatic keratinocytes but not in healthy skin. The CXCR1 could not be localized in psoriatic keratinocytes with immunohistochemistry and in situ hybridization, but infiltrating cells in the dermal compartment expressed both types of receptors. These data suggest that in addition to neutrophil activation by both CXCR1 and CXCR2, activation of keratinocytes mediated by CXCR2 could contribute to the characteristic epidermal changes observed in psoriasis.

Fibroblasts obtained from human nasal, laryngeal and tracheal mucosa produce the chemokine RANTES

RANTES is a chemokine that was already found in tissues obtained from nasal polyps of patients suffering from chronic polypous sinusitis and in lung biopsies of patients suffering from bronchial asthma. Nasal fibroblasts could be shown to be a cellular origin of RANTES. The aim of this study was to investigate whether human nasal, laryngeal and tracheal mucosa fibroblasts are differentiated in production of RANTES. Fibroblasts obtained from healthy human nasal, laryngeal and tracheal mucosa, were cultured. Secretion of RANTES-protein in supernatants was investigated after stimulation with 50 ng/ml tumor necrosis factor-alpha (TNF-alpha), interleukin-1-beta (IL-1-beta), lipopolysaccharide (LPS), phorbolmyrisate acetate (PMA), interferon-gamma (IFN-gamma) and serum-free medium (SFM) for 24 hours. Cultivated nasal, laryngeal and tracheal fibroblasts secreted RANTES-protein upon TNF-alpha, IL-1-beta and IFN-gamma stimulation. The amounts of RANTES-protein production ranged from 10 ng/ml (PMA) to 198 ng/ml (TNF-alpha). Secretion of significant amounts of RANTES-protein were detected in the supernatants from either nasal, laryngeal or tracheal fibroblasts. There was no significant difference between the differential fibroblasts. We conclude that nasal, laryngeal and tracheal fibroblasts could be a cellular source of RANTES in nasal and bronchial mucosa or in secrets of patients suffering from diseases where eosinophilic tissue infiltration represents a characteristic histopathological feature. Results suggest that additional local factors are needed to develop asthma bronchiale and chronic polypous sinusitis.

Fibroblasts but not epithelial cells obtained from human nasal mucosa produce the chemokine RANTES

RANTES is a chemokine that was already found in tissues obtained from nasal polyps of patients suffering from chronic polypous sinusitis. Its cellular origin is as yet unknown. The aim of this study was to investigate whether human nasal mucosa fibroblasts and epithelial cells are capable to produce RANTES. Fibroblasts and epithelial cells, obtained from healthy human nasal mucosa, were cultured. Expression of RANTES-mRNA and secretion of RANTES-protein in supernatants was investigated after stimulation with 50 ng/ml Tumour Necrosis Factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), interferon-g (IFN-gamma), lipopolysaccharide (LPS), phorbolymyristate acetate (PMA) and serum-free medium (SFM) for 24 h. Cultivated nasal fibroblasts either expressed RANTES-mRNA or secreted RANTES protein upon TNF-alpha, IL-1 beta and IFN-gamma stimulation. The amounts of RANTES-protein production ranged from 23 ng/ml (PMA) to 198 ng/ml (TNF-alpha). Nasal epithelial cells expressed RANTES-mRNA only after stimulation with PMA. Secretion of significant amounts of RANTES protein were not detected in the supernatants from nasal epithelial cells. We conclude that nasal fibroblasts but not epithelial cells could be a cellular source of RANTES in nasal mucosa or in secretions of patients suffering from diseases, where eosinophilic tissue infiltration represents a characteristic histopathological feature.

Increased expression of keratinocyte interleukin-8 in human contact eczematous reactions to heavy metals

Heavy metal-induced contact eczematous human skin reactions to cobalt chloride and mercuric chloride were investigated for immunoreactivity to interleukin-8 (IL-8), by using an indirect immunoperoxidase staining technique. There was suprabasal epidermal staining for IL-8, with a decrease in the vicinity of areas with parakeratotic epithelium. However, in the immediate vicinity of a vesicular formation, intense staining of some apically situated keratinocytes was found. In addition, increased immunoreactivity over the acrosyringial area compared with the surrounding epidermis was obtained. These findings indicate an increased synthesis of keratinocyte IL-8 in contact eczematous skin.

Interleukin-8 immunoreactivity in malignant tumours of the skin

In the past, interleukin-8 (IL-8) could be demonstrated within keratinocytes in normal epidermis and inflammatory skin diseases, like psoriasis and eczema. Using monoclonal antibodies, the distribution of IL-8 immunoreactivity was inversely related to the density of inflammatory infiltrate. Other in vitro observations indicated IL-8 to be a growth factor for keratinocytes. These results prompted an immunohistochemical examination of IL-8 immunoreactivity in malignant and semimalignant epithelial tumours of human skin. Whereas IL-8 could not be detected within the transformed cells of epithelial tumours or melanoma, some tumour cells within well differentiated squamous cell carcinoma and Bowen's disease showed IL-8 immunoreactivity. Thus, loss of IL-8 immunoreactivity can be a sign of malignant transformation. This indicates an important role in growth regulation as well as terminal differentiation of human keratinocytes.

Identification of an N-terminally truncated form of the chemokine RANTES and granulocyte-macrophage colony-stimulating factor as major eosinophil attractants released by cytokine-stimulated dermal fibroblasts

Eosinophil (Eo) granule proteins and, rarely, intact Eos represent a characteristic histopathologic feature of the dermal part of affected tissue in atopic dermatitis and some allergic reactions. Dermal fibroblasts are a rich source of cytokines and inflammatory mediators; therefore, we have investigated whether these cells release Eo chemoattractants when stimulated with different stimuli. Eo-chemotactic activity was detected after stimulation of cells with TNF-alpha and IL-1, but not when phorbol ester, PHA, or medium alone was used. Biochemical characterization of Eo-chemotactic activity in supernatants of NF-alpha-stimulated cells revealed both heparin-binding and nonbinding activity. HPLC purification with subsequent N-terminal sequencing and mass spectrometric analysis showed that the heparin-binding Eo-chemotactic peak corresponded to the chemokine [Tyr-RANTES]66 that also contained [Ser-RANTES]68 as contaminant, whereas the nonheparin-binding activity was identified as granulocyte-macrophage CSF (GM-CSF) by the use of neutralizing Abs. [Tyr-RANTES]66 was found to show identical behavior in the chemotaxis assay system with respect to potency and efficacy as natural [Ser-RANTES]68. These findings support the hypothesis that dermal fibroblasts can play an important role in the recruitment of Eo by release of the chemokine RANTES together with GM-CSF.

Identification of an N-terminally truncated form of the chemokine RANTES and granulocyte-macrophage colony-stimulating factor as major eosinophil attractants released by cytokine-stimulated dermal fibroblasts

Eosinophil (Eo) granule proteins and, rarely, intact Eos represent a characteristic histopathologic feature of the dermal part of affected tissue in atopic dermatitis and some allergic reactions. Dermal fibroblasts are a rich source of cytokines and inflammatory mediators; therefore, we have investigated whether these cells release Eo chemoattractants when stimulated with different stimuli. Eo-chemotactic activity was detected after stimulation of cells with TNF-alpha and IL-1, but not when phorbol ester, PHA, or medium alone was used. Biochemical characterization of Eo-chemotactic activity in supernatants of NF-alpha-stimulated cells revealed both heparin-binding and nonbinding activity. HPLC purification with subsequent N-terminal sequencing and mass spectrometric analysis showed that the heparin-binding Eo-chemotactic peak corresponded to the chemokine [Tyr-RANTES]66 that also contained [Ser-RANTES]68 as contaminant, whereas the nonheparin-binding activity was identified as granulocyte-macrophage CSF (GM-CSF) by the use of neutralizing Abs. [Tyr-RANTES]66 was found to show identical behavior in the chemotaxis assay system with respect to potency and efficacy as natural [Ser-RANTES]68. These findings support the hypothesis that dermal fibroblasts can play an important role in the recruitment of Eo by release of the chemokine RANTES together with GM-CSF.

Role of eosinophil-chemotactic C-C chemokines in cutaneous inflammation

In the dermal sites of atopic skin, eosinophil (Eo) granule protein or more rarely intact Eos represent a characteristic histological feature. We addressed the question of whether lesional scales of patients with various eosinophilic skin disorders contain Eo attractant and tried to characterize it biochemically. In scales of a patient with drug reaction, heparin-binding Eo attractants could be identified. High-performance liquid chromatographic analyses together with specific ELISA and Western blot analyses revealed identity with RANTES. No other heparin-binding Eo chemotaxin could be identified. HPLC analysis of pooled lesional scale extracts of patients with atopic dermatitis showed fractions containing only weak heparin-binding Eo-chemotactic activity, which, however, showed RANTES immunoreactivity. In experiments to elucidate the putative cellular origin of Eo-attracting chemokines in human skin we investigated supernatants of atopic skin we investigated supernatants of atopic skin-derived T lymphocytes as well as supernatants of stimulated dermal fibroblasts for Eo-chemotactic factors. Unexpectedly, we did not find any heparin-bound Eo attractants in supernatants of stimulated cultured atopic skin-derived T lymphocyte clones, whereas fibroblasts produced RANTES as well as granulocyte-macrophage colony-stimulating factor. Therefore, fibroblasts are likely source of eosinophil attractant cells, which could contribute to the Eo infiltrate. Selectivity of the infiltrate might come from selective induction of RANTES and/or induction of other as yet unidentified Eo-specific chemokines.

Immunohistochemical localization of cytokines and receptor-associated molecules in human tonsils and skin

Human tonsilla palatina and skin were investigated by means of light microscopical and electron microscopical immunohistochemistry using monoclonal antibodies (Mab) against some cytokines. In both tonsils and skin we found intracellular immunoreactivity for interleukin-1-beta in macrophages and interdigitating cells. Also some, but not all crypt-epithelial cells were positive, while keratinocytes in the skin were negative. Interleukin-2-immunoreactivity was found in a subpopulation of lymphocytes (probably T-cells) and unexpectedly also in some antigen-presenting cells (APCs). A Mab against interleukin-4 revealed weak labelling of lymphatic cells in the T-cell area of tonsils. The human skin was negative. A Mab that recognizes a molecule associated with the interleukin-4-receptor gave strong surface labelling in tonsils and skin on APCs and weak immunoreactivity on lymphoid cells. Frequently these APCs formed rosettes with weakly labeled lymphocytes. Mabs against interleukin-8 stained starry sky macrophages in the germinal centers of the tonsil and different APCs in the T-cell region. IL-8 is stored in keratinocytes of normal skin, but becomes mobilized under inflammatory conditions. Our results expand the understanding of cell cell-interactions under normal and inflammatory conditions in tonsil and skin.

Detection of the chemokine RANTES in cytokine-stimulated human dermal fibroblasts

A novel family of structurally and functionally related polypeptides has recently been detected that are now referred to as chemokines. Within this family, a peptide with the acronym RANTES was shown to be chemotactic for memory T cells, monocytes, and eosinophilic and basophilic granulocytes, thus suggesting it plays an important role in chronic inflammatory and allergic diseases. Murine monoclonal antibodies as well as cDNA probes specific for human RANTES were raised and extensively characterized. With these antibodies, stimulated human dermal fibroblasts were shown to express intracellular RANTES peptide by immunocytochemistry. Furthermore, similar kinetics could be demonstrated in fibroblasts for both RANTES mRNA expression and secretion of RANTES peptide using Northern blot hybridization and sandwich-enzyme-linked immunosorbent assay, respectively. RANTES expression was induced upon stimulation with tumor necrosis factor-alpha as well as with interleukin-1 alpha and -beta in a concentration- and time-dependent manner. These results reinforce the role of both resident and circulating cells in the production and release of RANTES and their participation in inflammatory processes.

Immunocytochemical localization of the chemokines RANTES and MIP-1 alpha within human platelets and their release during storage

The cytokines RANTES and MIP-1 alpha are 8-kD peptides which belong to the C-C subfamily of chemokines. They are both potent chemotactic factors for basophils and eosinophils. Apart from lymphocytes, the RANTES peptides was recently shown to be released from human platelets stimulated with thrombin [Kameyoshi et al: J Exp Med 1992;176:587-592]. Employing postembedding immunocytochemistry, we could detect RANTES and for the first time also MIP-1 alpha within the alpha-granules of human platelets. To date, MIP-1 alpha was not reported to occur in platelets. In slightly activated platelets, as found in stored platelet concentrates (PC), label for RANTES and MIP-1 alpha could also be observed within cisterns of the open canalicular system and on the plasma membrane, indicating a release of both peptides. These findings were confirmed by in vitro studies in PC, by investigation of RANTES and MIP-1 alpha release into the suspending medium. Over a period of 8 days, RANTES was steadily released in relatively high amounts, whereas MIP-1 alpha was measured in rather small amounts in the suspending medium. As RANTES and MIP-1 alpha, besides their chemotactic activity on eosinophils and basophils, are able to mediate the release of histamine, it is tempting to speculate about a participation of platelets in inflammatory reactions in which eosinophils and basophils are involved.

Urticarial and anaphylactoid reactions following ethanol intake

Ingestion of ethyl alcohol may be associated with a number of adverse reactions. Apart from toxicological effects, intolerance syndromes occur, which are caused by genetic or acquired defects in alcohol metabolism and are manifest clinically as flushing. In addition to these abnormalities, rare cases of generalized urticaria and anaphylactoid reactions after ingestion of ethyl alcohol have been reported, the pathogenesis of which is still a matter of debate. We describe three patients who presented with recurrent generalized urticaria, which developed within minutes of consumption of small amounts of ethyl alcohol. Common causes of chronic recurrent urticaria were excluded by case history, physical examination and laboratory investigations, and by comprehensive allergy testing. All patients produce positive prick tests with acetic acid, and developed urticaria after oral challenge with small amounts of highly purified ethyl alcohol. The symptoms are most probably caused by an intolerance to ethyl alcohol or its metabolites, whereas an allergy sensu strictu seems unlikely.

Time- and stimulus-dependent secretion of NAP-1/IL-8 by human fibroblasts and endothelial cells

The neutrophil-activating peptide 1/interleukin 8 (NAP-1/IL-8) has in the past been extensively characterized biochemically as well as functionally. Effects of NAP-1/IL-8 on inflammatory cells like neutrophilic granulocytes and lymphocytes, as well as its production by several different cell types, point towards an important role in different inflammatory processes. Recently, monoclonal antibodies have helped to establish immunoassays for detecting the peptide. Using such antibodies, we have performed in vitro studies on the time- and stimulus-dependent production of IL-8 by endothelial cells as well as fibroblasts. Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 alpha (IL-1 alpha) efficiently induced both focal intracellular expression as well as secretion of the peptide when tested by immunocytochemistry and enzyme-linked immunosorbent assay (ELISA). After stimulation with phorbol myristate acetate (PMA) and lipopolysaccharide (LPS), such effects were seen only in endothelial cells, whereas interferon (IFN)-gamma did not induce any pronounced effect on either of the cells tested. These studies demonstrated in vitro release of IL-8 by different cells upon specific stimulation, thus underlining the significance of the in vivo secretion of this peptide, as noted in recent studies.

IL-8 produced by human malignant melanoma cells in vitro is an essential autocrine growth factor

Normal melanocytes require a number of exogenous growth factors in contrast to most metastatic malignant melanomas. This investigation demonstrates that endogenously produced human IL-8 can act as an important growth factor for human melanoma cells. In the present study, six out of eight human melanoma cell lines tested secrete IL-8 protein into the culture supernatant. In two of these IL-8-secreting melanoma cell lines, SK-MEL 13 and SK-MEL 23, we have determined the IL-8 requirement for their proliferative capacity. These melanoma cell lines produced significant amounts of bioactive IL-8 as measured by the ELISA technique. Secretion of human IL-8 was inducible by IL-1 and by PMA. Human IL-8-specific mRNA was already detected in unstimulated melanoma cells. In addition, human IL-8-R mRNA could be detected for the first time in human melanoma cells. Exposure of the two melanoma cell lines in vitro to antisense oligonucleotides targeted against two different sites of human IL-8 mRNA-inhibited cell proliferation, colony formation in soft agar, and secretion of IL-8 protein into culture supernatant in a dose dependent fashion. Effects were reversible either by removal of the oligomers or by addition of exogenous IL-8 protein. In contrast, exposure to IL-8 sense probes or oligonucleotides in sense or antisense orientation specific for IL-7, TGF-alpha, TGF-beta, and MGSA had no such effect. A monospecific immune serum and two IL-8-specific mAb were also capable of inhibiting melanoma cell proliferation in the same manner. These results provide strong evidence for an autocrine IL-8 synthesis and for an IL-8-dependent proliferation in a subgroup of human melanomas. Furthermore, they suggest that IL-8 may play a role not only in immunomodulation but also in melanoma progression and metastatic spread.

IL-8 produced by human malignant melanoma cells in vitro is an essential autocrine growth factor

Normal melanocytes require a number of exogenous growth factors in contrast to most metastatic malignant melanomas. This investigation demonstrates that endogenously produced human IL-8 can act as an important growth factor for human melanoma cells. In the present study, six out of eight human melanoma cell lines tested secrete IL-8 protein into the culture supernatant. In two of these IL-8-secreting melanoma cell lines, SK-MEL 13 and SK-MEL 23, we have determined the IL-8 requirement for their proliferative capacity. These melanoma cell lines produced significant amounts of bioactive IL-8 as measured by the ELISA technique. Secretion of human IL-8 was inducible by IL-1 and by PMA. Human IL-8-specific mRNA was already detected in unstimulated melanoma cells. In addition, human IL-8-R mRNA could be detected for the first time in human melanoma cells. Exposure of the two melanoma cell lines in vitro to antisense oligonucleotides targeted against two different sites of human IL-8 mRNA-inhibited cell proliferation, colony formation in soft agar, and secretion of IL-8 protein into culture supernatant in a dose dependent fashion. Effects were reversible either by removal of the oligomers or by addition of exogenous IL-8 protein. In contrast, exposure to IL-8 sense probes or oligonucleotides in sense or antisense orientation specific for IL-7, TGF-alpha, TGF-beta, and MGSA had no such effect. A monospecific immune serum and two IL-8-specific mAb were also capable of inhibiting melanoma cell proliferation in the same manner. These results provide strong evidence for an autocrine IL-8 synthesis and for an IL-8-dependent proliferation in a subgroup of human melanomas. Furthermore, they suggest that IL-8 may play a role not only in immunomodulation but also in melanoma progression and metastatic spread.

Interleukin-8 is not involved in the increased chemotactic activity of peripheral blood plasma during acute myocardial infarction

Polymorphonuclear neutrophils (PMN) are known to participate in the development of tissue injury during myocardial infarction due to both free oxygen radicals release, as well as to their involvement in the "no-reflow" phenomenon. We have previously shown that peripheral blood plasma (obtained from patients with acute myocardial infarction) has chemotactic activity for PMN and is able to induce PMN adherence as well as superoxide anion production. To investigate whether interleukin-8 (IL-8/NAP-1), a potent chemotactic factor for PMN, is involved in plasma-mediated PMN stimulation, we measured plasma levels of IL-8 in five patients with transmural myocardial infarction with highly sensitive enzyme-linked immunosorbent assay (ELISA) using specific antibodies. Blood samples were taken immediately after patients' admission, within 15 and 30 min of treatment with intravenous nitrates, as well as after 1, 2, 3, and 7 days. All samples expressed IL-8 activity within the detection limit (0.4 ng/ml) as observed at the basal state. Thus, IL-8 may not be considered as responsible for the chemotactic activity in peripheral blood in patients with myocardial infarction.

Pro- and anti-inflammatory cytokines in primary systemic vasculitis

The expression of cytokines that are potentially involved in the pathogenesis of vasculitis was studied in patients with primary systemic vasculitis (PSV). In extension of earlier reports, we detected an overexpression of transforming growth factor beta (TGF beta), interleukin 6 (IL6), and interleukin 8 (IL8), indicating that the whole cytokine cascade is activated to a significant extent in PSV.

Elevated levels of NAP-1/interleukin-8 are present in the airspaces of patients with the adult respiratory distress syndrome and are associated with increased mortality

The adult respiratory distress syndrome (ARDS) is characterized by increased neutrophils within the airspaces of the lungs. In order to determine if neutrophil activating protein (NAP)-1/interleukin-8 (NAP-1/IL-8) could be an important cause of neutrophil influx and activation in ARDS, we examined fluid, which was either directly aspirated or lavaged with saline from the lungs of patients with ARDS. NAP-1/IL-8 was present in significantly higher concentrations in the fluids of patients with ARDS compared with control subjects. There was a significant correlation between the percentage of neutrophils in the lavage fluids and the NAP-1/IL-8 concentration (r2 = 0.74). Furthermore, the NAP-1/IL-8 concentration of the pulmonary edema fluid was equivalent to the optimal concentration required to induce neutrophil chemotaxis in vitro. Although not all of the chemotactic activity of the edema fluid was removed by an anti-NAP-1/IL-8 affinity column, the data established that NAP-1/IL-8 is an important neutrophil chemotaxin in the airspaces of patients with ARDS. In addition, those patients with very high concentrations of NAP-1/IL-8 in their bronchoalveolar lavage fluids had a higher mortality rate than those patients with lower concentrations of NAP-1/IL-8. The correlation between NAP-1/IL-8 concentration and mortality is not paralleled by total protein concentration and mortality.

Neutrophil attractant protein-1-immunoglobulin G immune complexes and free anti-NAP-1 antibody in normal human serum

After obtaining data indicating the presence of a neutrophil attractant protein-1 (NAP-1)-IgG complex in normal human serum, we developed sandwich ELISAs that could quantify NAP-1 and NAP-1-IgG in mixtures of the two moieties. The ELISA for free NAP-1 used a monoclonal capture antibody that did not bind NAP-1-IgG. The ELISA for NAP-1-IgG was based on omission of the anti-NAP-1 detection antibody (required for the free NAP-1 ELISA) and on interaction of phosphatase-conjugated anti-human IgG with the human NAP-1-IgG complex. Gel filtration of immunoaffinity-purified NAP-1-IgG showed that the bulk of the complex comprised a single IgG. Binding between NAP-1 and antibody is strong, since 8 M urea at neutral or alkaline pH did not release NAP-1. However, at pH 2.0 in 9 M urea approximately 15% of the total NAP-1 could be dissociated from the complex. NAP-1-IgG was detected in 18 of 26 sera from normal humans. The mean serum concentration was 58 ng of IgG-bound NAP-1/ml, with an SEM of 16 and a range from undetectable to 247 ng/ml. NAP-1-IgG concentrations in paired sera drawn at a 1-mo interval were remarkably constant. Using an ELISA for free NAP-1 with a detection limit of 200 pg/ml, we found no free NAP-1 in the 26 sera. Free anti-NAP-1-IgG autoantibody was found in 9 of 26 sera by direct ELISA. IgG anti-NAP-1 of all nine sera was polyclonal, comprising both kappa and lambda isotypes; predominant subclasses were IgG2 and IgG3. NAP-1-IgG did not compete with 125I-NAP-1 for binding to neutrophils, which suggests that IgG anti-NAP-1 is a molecular trap that prevents binding of NAP-1 to neutrophils after it diffuses from production sites into the circulation.

Immunohistochemical studies on NAP-1/IL-8 in contact eczema and atopic dermatitis

The neutrophil activating peptide NAP-1/IL-8 has in the past been shown to be secreted by diverse cell-types involved in inflammatory processes. Furthermore, potent biological effects on both neutrophilic granulocytes and lymphocytes enforce its role in inflammation. Recently, immunohistochemical studies using monoclonal anti-NAP-1/IL-8 antibodies have been performed on dermal inflammatory conditions like psoriasis vulgaris. These have demonstrated epidermal IL-8 immunoreactivity in a pattern inversely related to the degree of inflammatory infiltration. Based on these results, in the present study biopsies from patients with contact eczema as well as atopic dermatitis were examined. The same patterns of immunoreactivity were found with either homogeneous epidermal staining, focally negative staining or overall decreased or even absent staining. As in psoriasis, these patterns were related to the degree of inflammatory infiltration. These results prove NAP-1/IL-8 to be involved not only in psoriasis vulgaris, but more likely to be a marker of different inflammatory processes. Future work will have to examine the kinetics as well as stimuli causing these effect.