Biomedical subjects

L Koenderman

Publications and source records attributed to L Koenderman.

At least 91 records · Page 5Linked to original sources

PubMed1995

Cognate interaction between human lymphocytes and eosinophils is mediated by beta 2-integrins and very late antigen-4.

Here the cognate interactions between human eosinophils and lymphocytes are studied. These interactions were measured in a double-colored FACS analysis by applying fluorescent red eosinophils (stained with hydroethidine, 40 mumol/L) and fluorescent green lymphocytes (stained with sulfidofluorescein diacetate, 100 mumol/L) in a ratio of 1:3. When normal eosinophils were mixed with a total lymphocyte preparation in stirred suspensions (37 degrees C), no physical interaction was present between both cell types. However, the addition of phytohemagglutinin and PMA resulted in a clear aggregation response between both cell types (up to 30% of the eosinophils interacted with lymphocytes after 15 minutes). CD8(+)- and CD4(+)-positive T cells contributed equally to the heterotypic aggregation response. It is interesting that when lymphocytes were pretreated with phytohemagglutinin or eosinophils with phorbol myristate acetate and subsequently washed, the cells still interacted with unstimulated counterparts. The heterotypic interaction between lymphocytes and eosinophils is blocked by monoclonal antibodies directed against the beta-chain of the beta 2-integrins (CLB LFA1/1; CD18) and the alpha-chain of very late antigen-4 (VLA-4) (HP2/1; CD49d), indicating that both the beta 2-integrins and VLA-4 contributed to this heterotypic interaction. When eosinophils bound to PHA-treated lymphocytes, the cells exhibited an activated phenotype that was characterized by an enhanced expression of CD66b and CD11b. The cells interacted with each other provided that an intact cellular metabolism was present--that is, no interaction was seen after treatment with the glycolysis inhibitor sodium mono-iodoacetate.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗

PubMed1994

Cooperation between Fc gamma receptor II and complement receptor type 3 during activation of platelet-activating factor release by cytokine-primed human eosinophils.

After priming with cytokines, such as granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-3, or IL-5, eosinophils are stimulated potently by opsonized particles like serum-treated zymosan (STZ), resulting in activation of the respiratory burst and production of lipid mediators, such as platelet-activating factor (PAF) and leukotriene C4 (LTC4). In the present study, the role of the opsonin receptors Fc gamma RII and CR3 during both STZ-induced activation of the respiratory burst and PAF release by human eosinophils was investigated. Inhibition studies with blocking mAbs (alpha hFc gamma RII: AT10, IV.3; alpha CR3: B2.12, 44a) showed that both Fc gamma RII and CR3 are important for STZ-induced PAF release by cytokine-primed eosinophils. In contrast, CR3 is involved in activation of the respiratory burst, whereas Fc gamma RII seems not to be important, because blocking anti-Fc gamma RII mAbs had no effect. Subsequently, experiments were performed with zymosan particles coated with IgG, iC3b, or a combination of both. IgG-coated particles poorly activated both responses in GM-CSF primed and unprimed cells. iC3b-Zymosan activated the respiratory burst as well as zymosan expressing both opsonins (IgG/iC3b-zymosan). In contrast, iC3b-zymosan induced significantly less PAF release by GM-CSF-primed eosinophils than did IgG/iC3b-zymosan, suggesting synergism between Fc gamma RII and CR3. This synergistic effect was not observed when IgG-zymosan and iC3b-zymosan were added simultaneously. Therefore, these data indicate that on human eosinophils, Fc gamma RII and CR3 act synergistically to activate PAF release, provided that their ligands are in close proximity.

Cytokines↗

PubMed1994

RANTES- and interleukin-8-induced responses in normal human eosinophils: effects of priming with interleukin-5.

We report that responses of normal human eosinophils toward the chemokines RANTES and interleukin-8 (IL-8) are modulated and upregulated by priming with IL-5. In a modified Boyden chamber assay, we studied migratory responses toward the members of the chemokine family RANTES, monocyte chemotactic protein-1 (MCP-1), and macrophage inflammatory protein-1 alpha (MIP-1 alpha) (C-C subfamily), and IL-8, platelet factor-4 (PF-4), and neutrophil-activating peptide-2 (NAP-2) (C-x-C subfamily). These chemokines were also studied in terms of actin polymerization and ([Ca2+]i)-mobilizing properties, intracellular signals that are thought to play a role during migratory responses. We found that eosinophils showed significant migratory responses toward RANTES and IL-8 at concentrations of 10(-9) to 10(-7) mol/L only after priming with IL-5 (10 pmol/L). At these concentrations, PF-4, NAP-2, MCP-1, and MIP-1 alpha induced no significant migratory responses after priming. Unprimed eosinophils only showed a significant migratory response toward RANTES (10(-6) mol/L). Changes in [Ca2+]i were found after addition of RANTES, MIP-1 alpha, and NAP-2 (10 nmol/L) to unprimed eosinophils. RANTES (10(-9) to 10(-7) mol/L) significantly induced actin polymerization both in primed and unprimed eosinophils, whereas IL-8 (10(-9) to 10(-8) mol/L) and MIP-1 alpha (10(-8) mol/L) only induced actin polymerization after priming with IL-5. NAP-2, PF-4, and MCP-1 did not affect actin polymerization. These findings are further evidence for the hypothesis that cytokines like IL-5 and locally secreted chemokines like RANTES and IL-8 are both at the basis of specific eosinophil influx into the allergic inflammatory locus.

Actins↗

PubMed1994

Granulocyte-macrophage colony-stimulating factor, interleukin-3 (IL-3), and IL-5 greatly enhance the interaction of human eosinophils with opsonized particles by changing the affinity of complement receptor type 3.

Eosinophil functions can be modulated by several cytokines such as granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and IL-5. We have investigated the modulatory role of these cytokines on the interaction of human eosinophils with opsonized particles (serum-treated zymosan [STZ]). Addition of STZ to eosinophils isolated from the peripheral blood of normal human donors resulted in an interaction of the STZ particles with only 15% to 25% of the cells. Treatment of the eosinophils with GM-CSF, IL-3, or IL-5 strongly enhanced both the rate of particle binding and the percentage of eosinophils binding STZ. The effect of the cytokines is most likely mediated by a change in affinity of the complement receptor type 3 (CR3) on the eosinophils for the complement fragment iC3b on the STZ particles. This is indicated by the observation that (1) the effect of the cytokines on STZ binding was prevented by a monoclonal antibody against the iC3b-binding site on CR3 and (2) the enhanced binding was already apparent before upregulation of CR3 on the cell surface was observed. In a previous study, similar results were obtained with platelet-activating factor (PAF)-primed eosinophils. Because we found that the cytokines strongly enhanced the STZ-induced PAF synthesis, we investigated the role of both released PAF and cell-associated PAF in the priming phenomenon by the cytokines. Cytokine priming appeared to be largely independent of the synthesis of PAF.

Eosinophils↗

PubMed1994

12-O-tetradecanoylphorbol-13-acetate- and tumor necrosis factor alpha-mediated induction of intercellular adhesion molecule-1 is inhibited by dexamethasone. Functional analysis of the human intercellular adhesion molecular-1 promoter.

Transcription regulation of the human intercellular adhesion molecule-1 gene by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), tumor necrosis factor alpha (TNF alpha), and the glucocorticoid dexamethasone was studied using transient transfections in 293 cells with intercellular adhesion molecule-1 promoter-luciferase constructs (together with a glucocorticoid receptor expression vector). TPA and TNF alpha induced promoter activity, which was repressed by dexamethasone. Four TPA-responsive DNA regions were identified, each containing a potential TPA-responsive enhancer sequence: 1) -677/-340 an AP3-like sequence; 2) -290/278 a TPA-response element (TRE); 3) -227/-175 an NF kappa B-like sequence; 4) -105/-38 an AP2-like sequence. TNF alpha enhanced transcription only through region 3. The TRE in region 2 appeared to be functionally coupled to a distal TATA box at -313 and differed from the consensus TRE with respect to binding characteristics for members of the AP1 family. The newly identified NF kappa B enhancer (TGGAAATTCC) is bound by a TNF alpha-induced nuclear protein and appears to be the key element in rapid transcription induction by TNF alpha (and TPA), while transactivation of this element is repressed by the ligand-bound glucocorticoid receptor. We propose a negative cross-talk between the NF kappa B transcription factor and the glucocorticoid receptor.

Base Sequence↗

PubMed1994

Immunophenotyping of eosinophils recovered from blood and BAL of allergic asthmatics.

Studies of bronchoalveolar lavage (BAL) fluid from patients with allergic asthma have demonstrated active migration of eosinophils into the bronchial lumen after allergen challenge. The mechanisms mediating this eosinophil infiltration and cell activation are largely unexplained. The expression of several cell-surface molecules was measured on eosinophils derived from blood and BAL fluid 4 h after an allergen-induced early asthmatic reaction in order to find indications for a role of these molecules during extravasation to and activation in the bronchial compartment. Nine patients with allergic asthma participated in the study. An eosinophil-specific, high-depolarization signal enabled us to measure expression on eosinophils in a fluorescence activated cell sorter (FACS) analysis without isolation of these cells. Eosinophils recovered from BAL showed a different phenotype than blood eosinophils; upregulation of CR-3, p150/95, CD67, and CD63, and downregulation of L-selectin indicate that the cells are activated in terms of degranulation. Up-regulation of intercellular adhesion molecule-1 (ICAM-1), LFA-3, and human leukocyte antigen II (HLA-II) might enable cell-cell contact between T-lymphocytes and eosinophils, probably leading to immunomodulation and cell activation. The finding that eosinophils in BAL are activated and can interact with T cells is further evidence for the proinflammatory role of these cells in allergic asthma.

Adult↗

PubMed1993

Relative contributions of human types 1 and 2 T-helper cell-derived eosinophilotrophic cytokines to development of eosinophilia.

The relative contributions of type 1 and 2 T-helper (Th1 and Th2) cell-derived interleukin (IL-5), granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-3 were studied in the regulation of sequential events in the development of eosinophilia. Using eosinophils from normal donors and neutralizing antibodies that selectively block cytokine activities, we analyzed the effects of these cytokines in supernatants (SN) of well-characterized allergen-specific Th2 and Th1 T-lymphocyte clones (TLC) generated from atopic and nonatopic individuals, respectively. Eosinophil colony formation from CD34+ bone marrow progenitor cells in semisolid cultures could be induced both by Th1 and Th2 SN, mainly mediated by the synergistic effects of GM-CSF and IL-3, whereas IL-5 had only a minor additive effect. High production of mature eosinophils in liquid cultures of unseparated mononuclear bone marrow cells could only be induced by Th2 SN, which could be more than 90% blocked by anti-IL-5, but not by anti-IL-3 or anti-GM-CSF. Chemotaxis of mature peripheral blood eosinophils could equally well be induced by Th1 and Th2 SN, although the relative contribution of the individual cytokines was clearly different in the two sets of SN. Priming of platelet-activating factor (PAF) release by peripheral blood eosinophils was regulated by additive effects of the three cytokines and was stronger induced by the Th2 SN than by the Th1 SN. The present results indicate that IL-5, GM-CSF, and IL-3 control eosinophils throughout the course of development of eosinophilia, having different individual contributions in different compartments. The apparent strong and selective IL-5-dependence of certain yet undefined steps in eosinophil production in the bone marrow supports the concept of the generally assumed causal relation between predominant activation of IL-5-producing Th2 cells in response to allergens and development of eosinophilia in atopic disease.

Bone Marrow Cells↗

PubMed1993

A novel syndrome of severe neutrophil dysfunction: unresponsiveness confined to chemotaxin-induced functions.

We have identified a patient with a number of neutrophil dysfunctions. The patient was a female baby who lived for 8 months. During her life, she developed severe bacterial infections and showed omphalitis, impaired wound healing, and a pronounced leukocytosis. She was not a patient with leukocyte adhesion deficiency, because all leukocyte CD18 complex proteins were expressed at normal levels. Yet, neutrophil polarization and chemotaxis to platelet-activating factor, leukotriene B4, or formyl-methionyl-leucyl-phenylalanine (FMLP) were completely absent. We found a strong defect in actin polymerization in response to chemotactic stimuli, but only a retarded or even normal reaction with other stimuli. This indicates that the cellular dysfunctions were not due to an intrinsic defect in actin metabolism. Instead, the regulation of actin polymerization with chemotactic stimuli seemed to be defective. We concentrated on FMLP-induced responses in the patient's neutrophils. Functions dependent on activation of complement receptor type 3, such as aggregation or adherence to endothelial cells, were normally induced. Binding to serum-coated coverslips was normal in cell number; however, spreading was not observed. Exocytosis from the specific granules was readily induced. In contrast, FMLP failed to induce a respiratory burst activity or degranulation of the azurophil granules. FMLP induced a normal increase in free intracellular Ca2+, but a decreased formation of diglycerides (especially the 1-O-alkyl,2-acyl compounds). Thus, we have described a patient whose neutrophils show a severe defect in functional activation via chemotaxin receptors, resulting in a selective absence of NADPH oxidase activity, exocytosis from the azurophil granules, and actin polymerization. Our findings show that actin polymerization for neutrophil spreading and locomotion is regulated differently from that for phagocytosis. Also, the release of azurophil and specific granule contents is clearly shown to be regulated in a different way.

Actins↗

PubMed1993

Granulocyte-macrophage colony-stimulating factor induces sequential activation and deactivation of binding via a low-affinity IgG Fc receptor, hFc gamma RII, on human eosinophils.

Eosinophils are important in antibody-mediated immune defense against parasites based on interaction with Ig receptors (FcR). Of the three classes of IgG FcR in humans, hFc gamma RI, II, and III, solely hFc gamma RII (CD32) is expressed on freshly isolated eosinophils. Despite an expression level similar to that found on monocytes and polymorphonuclear granulocytes, binding activity of hFc gamma RII on eosinophils is constitutively low. Freshly isolated eosinophils had a negligible ability to form rosettes with IgG-sensitized erythrocytes (EA-IgG). Addition of granulocyte-macrophage colony-stimulating factor (GM-CSF) caused an approximately threefold increase in EA-IgG rosettes. This increase was maximal after 35 minutes, and declined upon further incubation at 37 degrees C. Analysis of hFc gamma RII expression levels showed no significant changes and neither was the expression of other hFc gamma R classes induced. Blocking studies with anti-Fc gamma receptor monoclonal antibody (MoAb) proved hFc gamma RII specificity of enhanced IgG complex binding. These phenomena were not restricted to GM-CSF action, because the addition of interleukin-3 or interleukin-5 similarly enhanced EA-IgG binding. The kinetics of activation of hFc gamma RII binding activity were paralleled by the binding of EA-C3bi to CR3 on eosinophils. In contrast to the stable expression of hFc gamma RII during activation with GM-CSF, CR3 expression increased slowly. Ligand binding via both types of opsonin receptors proved receptor specific. However, the kinetics of enhanced binding via hFc gamma RII and CR3 suggested the possibility of a common mechanism underlying the enhancement of ligand binding via hFc gamma RII and CR3. This hypothesis was supported by the fact that binding via hFc gamma RII proved sensitive to both high concentrations of F(ab')2 fragments of anti-CD11b MoAb MO1 and chelation of bivalent cations with EDTA. In conclusion, our studies indicate that cytokines can induce a transient enhancement of hFc gamma RII binding activity. Qualitative, and not quantitative, changes in this receptor appear to underly the modulation of binding activity, which may be linked to changes in CR3 activity.

Cells, Cultured↗

PubMed1993

Human platelets secrete chemotactic activity for eosinophils.

Thrombin-stimulated platelets liberate factors that induce chemotaxis of eosinophils and raise their cytosolic Ca2+ content ([Ca2+]i). The sources of this activity are the dense- and alpha-granules because inhibition of prostaglandin endoperoxide/thromboxane A2 formation and the platelet-activating factor receptor-antagonist WEB 2086 have no effect. Platelets from patients with Storage-Pool Deficiency show about 60% of the normal chemotactic activity with little effect on [Ca2+]i, whereas completely degranulated platelets fail to affect eosinophils. In concentrations secreted by the platelets, adenosine diphosphate (ADP), and platelet factor 4 have no effect, whereas adenosine triphosphate (ATP) induces a strong chemotactic response and increases [Ca2+]i. However, apart from ATP other modulating factors must be involved as platelet releasates induce more chemotaxis than ATP alone. Thus, platelets secrete factors that activate eosinophils and may contribute to inflammatory and allergic processes.

Adenosine Diphosphate↗

PubMed1993

Cytokine priming of the respiratory burst in human eosinophils is Ca2+ independent and accompanied by induction of tyrosine kinase activity.

We report that pretreatment of human eosinophils with GM-CSF, IL-3, or IL-5 enhanced the respiratory burst induced by opsonized particles. In order to gain more insight into the intracellular mechanism(s) involved in cytokine priming, the role of [Ca2+]i and tyrosine kinases was studied. Optimal priming concentrations of GM-CSF, IL-3, and IL-5 did not induce a rise in [Ca2+]i, and Ca(2+)-depleted eosinophils ([Ca2+]i < 20 nM) were still primed after preincubation with these cytokines. GM-CSF, IL-3, and IL-5 induced phosphorylation of two proteins (102 and 122 kd) on tyrosine residues, as deduced from Western blot analysis with an antiphosphotyrosine monoclonal antibody (4G10). This cytokine-stimulated tyrosine phosphorylation was not inhibited under Ca(2+)-depleted conditions. In conclusion, this study demonstrates that GM-CSF, IL-3, and IL-5 priming of the opsonized particle-induced respiratory burst in human eosinophils is completely Ca2+ independent. Moreover the tyrosine phosphorylation of a 102-kd and a 122-kd protein is Ca2+ independent, suggesting that this event might be involved in cytokine priming.

Calcium↗

PubMed1993

Transient exposure of human eosinophils to the protein kinase C inhibitors CGP39-360, CGP41-251, and CGP44-800 leads to priming of the respiratory burst induced by opsonized particles.

We report that a transient incubation of human eosinophils with the protein kinase C (PKC) inhibitor CGP39-360 (staurosporine) or the more PKC-specific inhibitors CGP41-251 and CGP44-800 prior to activation of the respiratory burst with opsonized particles results in priming of this response. This priming effect was concentration dependent and occurred in the range in which the phorbol myristate acetate-induced respiratory burst was inhibited. CGP39-360 priming was minimally affected in Ca(2+)-depleted cells, indicating that an increase in [Ca2+]i is not important. Also, the binding of serum-treated zymosan (STZ) particles was strongly enhanced by the inhibitors. On the other hand, the release of platelet-activating factor (PAF) induced by opsonized particles was enhanced only by CGP39-360 and not by CGP41-251 and CGP44-800. Therefore, priming of the respiratory burst is not due to an aspecific enhancing effect of the inhibitors. These data indicate that different signal transduction routes are involved in priming of the STZ-induced respiratory burst and PAF release in human eosinophils.

Alkaloids↗

PubMed1993

Effects of nedocromil sodium on in vitro induced migration, activation, and mediator release from human granulocytes.

Using the allergen-induced late-phase asthmatic reaction as a working model, we studied the activity of certain inflammatory cells and their reaction to nedocromil sodium. The processes that were examined in vitro included the following: the chemotaxis of purified neutrophils and eosinophils, the early steps of neutrophil and eosinophil activation, and the release of mediators from these cells. Nedocromil sodium strongly inhibited neutrophil mobilization caused by four chemotactic factors (zymosan activated serum, N-formyl-methionyl-leucyl-phenylalanine platelet-activating factor [PAF], and leukotriene B4 [LTB4] and eosinophil mobilization caused by two factors (PAF and LTB4). In vitro treatment of eosinophils from normal subjects with picomolar concentrations of interleukin-3, interleukin-5, or granulocyte-macrophage colony stimulating factor increased the chemotactic responsiveness toward PAF and LTB4 and induced a chemotactic responsiveness toward N-formyl-methionyl-leucyl-phenylalanine and neutrophil activating factor/interleukin-8. The zymosan activated serum-induced chemotactic responsiveness remained unaltered. Nedocromil sodium inhibited the cytokine-primed chemotactic responsiveness to the various chemotaxins, not the influence of the cytokines on the cells. Activation of granulocytes, as measured by Ca2+ influx, was not inhibited by nedocromil sodium. Mediator formation in eosinophils was modified only slightly. These results suggest that inhibiting the mobilization of inflammatory cells in the lung tissue may be an important action of nedocromil sodium. Therefore these effects may be relevant to the treatment of asthma given the role of airway inflammation in this disease process.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1993

Inhibition of cytokine-primed eosinophil chemotaxis by nedocromil sodium.

BACKGROUND: Eosinophil influx into the lung tissue is considered to be relevant for the pathogenesis of asthma. Various chemotactic factors may be responsible for this influx. Recently it has been demonstrated that the cytokines granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and interleukin-5 (IL-5) are present in the circulation of individuals with allergic asthma. These cytokines have the capacity to modulate chemotactic responses of eosinophils toward platelet-activating factor, formyl-methionyl-leucyl-phenylalanine, (FMLP) and neutrophil-activating factor (NAF)/IL-8, but not toward complement fragment C5a (C5a). Here the effect of nedocromil sodium on the chemotactic response of eosinophils from allergic asthmatic individuals and from normal donors preincubated with GM-CSF or IL-3 toward FMLP, NAF/IL-8 was evaluated. RESULTS: Nedocromil sodium inhibited the chemotactic response toward FMLP and NAF/IL-8 of GM-CSF primed eosinophils approximately 60% (inhibitory concentration of 50% [IC50] approximately 1 to 10 nmol/L), whereas these responses of IL-3 primed eosinophils was completely inhibited (IC50 approximately 1 nmol/L). CONCLUSIONS: The chemotactic responses toward C5a were inhibited by nedocromil sodium at higher concentrations than were required in the priming studies (IC50 approximately 10 to 100 nmol/L). Nedocromil sodium (0.1 mumol/L) was also effective in inhibiting the chemotactic response toward FMLP (10 nmol/L) of eosinophils isolated from the circulation of patients with allergic asthma 3 hours after allergen challenge. These findings might explain in part the antiinflammatory action of nedocromil sodium.

Adult↗

PubMed1993

Upregulation of formyl-peptide and interleukin-8-induced eosinophil chemotaxis in patients with allergic asthma.

BACKGROUND: The cytokine granulocyte-macrophage colony-stimulating factors, interleukin-3 and interleukin-5, are important modulators of eosinophilia and eosinophil function. In particular, eosinophil chemotaxis is very sensitive to cytokine priming. METHODS: We evaluated chemotactic responses of eosinophils from patients with allergic asthma. These cells exhibited a primed phenotype as deduced from enhanced responses toward formyl-methionyl-leucyl-phenylalanine and platelet-activating factor and a decreased responsiveness toward granulocyte-macrophage colony-stimulating factor. Bronchoprovocation of patients with allergic asthma with allergen was performed as a possible means to enhance in vivo priming. RESULTS: Indeed, eosinophils isolated 3 hours after allergen challenge exhibited a more pronounced primed phenotype, which was reflected by an induction of responsiveness towards interleukin-8. Eosinophil responses induced by platelet-activating factor, formyl-methionyl-leucyl-phenylalanine, complement fragment C5a, interleukin-3, interleukin-5, and granulocyte-macrophage colony-stimulating factor were not significantly altered after allergen challenge. CONCLUSION: These data provide further evidence that eosinophils are already primed in the peripheral blood of individuals with allergic asthma. This is most likely due to the presence of circulating cytokines in the peripheral blood of those individuals. This in vivo priming results in selective upregulation and downregulation of responses toward various chemotaxins, which may be released in the lungs during allergic inflammation.

Adult↗

PubMed1993

Eosinophil migration in atopic dermatitis. I: Increased migratory responses to N-formyl-methionyl-leucyl-phenylalanine, neutrophil-activating factor, platelet-activating factor, and platelet factor 4.

Eosinophil granular protein deposits have been demonstrated in lesional atopic dermatitis skin. This suggests active tissue infiltration of eosinophils. To find an explanation for the tissue influx of eosinophils, eosinophil migration was studied in vitro by means of a microchemotaxis assay. Eosinophils from the circulation of patients with atopic dermatitis showed an altered capacity to respond to chemotactic stimuli in vitro compared with eosinophils from healthy donors. Eosinophils from patients with atopic dermatitis had significantly increased migratory responses toward dose ranges of N-formyl-methionyl-leucyl-phenylalanine, neutrophil-activating factor, platelet-activating factor, and platelet factor 4. Eosinophils from normal individuals did not respond to N-formyl-methionyl-leucyl-phenylalanine and neutrophil-activating factor and responded only slightly to platelet factor 4. The migratory responses toward tumor necrosis factor-alpha and complement factor C5a were identical in both groups. Interleukin-5, an eosinophil-selective cytokine, is a strong modulator of the migratory responses to these chemotaxins in eosinophils from normal donors. A migratory response toward N-formyl-methionyl-leucyl-phenylalanine and neutrophil-activating factor was induced by interleukin-5, whereas the migratory response toward platelet-activating factor and platelet factor 4 was markedly potentiated. In contrast, the response to complement fragment C5a was only slightly influenced. Our findings indicate that the increased migratory responsiveness of eosinophils from patients with atopic dermatitis to various chemotaxins reflects in vivo "priming" of eosinophils, presumably by circulating cytokines such as interleukin-5. This in vivo "priming" is not optimal because it can be further potentiated by renewed contact with interleukin-5.

Adolescent↗

PubMed1993

Down modulation of L-Selectin expression on eosinophils recovered from bronchoalveolar lavage fluid after allergen provocation.

In allergic asthma eosinophils infiltrate into the lung after allergen challenge. The mechanism of this cellular infiltration is not fully understood. L-Selectin is involved in leucocyte-endothelial cell recognition and participates in homing of leucocytes into sites of inflammation. To find indications for a role of L-Selectin in the migration of eosinophils to the bronchoalveolar space we measured L-Selectin expression on eosinophils in peripheral blood and bronchoalveolar lavage fluid (BAL) 4 hr after the early allergic reaction after allergen challenge. Nine patients with allergic asthma participated in the study. An eosinophil specific high depolarization signal enabled us to measure L-Selectin expression on eosinophils in a FACS analysis without isolation of these cells. Eosinophils recovered from BAL showed a strong decrease of L-Selectin expression compared to blood eosinophils. This decrease in L-Selectin expression can be induced in vitro by activation of eosinophils with PMA or FMLP whereas priming of eosinophils during several hours with GM-CSF did not influence L-Selectin expression. Our results are a first indication that L-Selectin may play a role during homing of eosinophils in the lung in asthma after allergen challenge. Moreover, the low expression of L-Selectin on eosinophils in the lung is a further indication that these cells exhibit an activated phenotype.

Adult↗

PubMed1993

Glucocorticoid-mediated repression of intercellular adhesion molecule-1 expression in human monocytic and bronchial epithelial cell lines.

Increased expression of the intercellular adhesion molecule-1 (ICAM-1) on cells present in the airways has been suggested to play a role in the pathogenesis of asthma by enhancing airway inflammation. We used the monocytic U937 cell line, both undifferentiated and differentiated to a macrophage-like phenotype, and the bronchial epithelial cell line NCI-H292 as cellular model systems for human monocytes/macrophages and bronchial epithelial cells, respectively, and studied the effects of 12-O-tetradecanoyl phorbol-13-acetate (TPA) and dexamethasone on ICAM-1 expression. Both cell lines expressed the ICAM-1 protein constitutively. In addition, TPA- or 1,25-dihydroxyvitamin D3-mediated differentiation of the U937 cell line into a macrophage-like phenotype was associated with increased expression of ICAM-1. In both cell lines, two ICAM-1 mRNA transcripts were found, and expression was stimulated to a similar degree within 1 to 2 h after addition of TPA. In both cell lines, the anti-inflammatory corticosteroid dexamethasone repressed both constitutive and TPA-stimulated ICAM-1 expression, within 3 h of its addition. In the presence of cycloheximide, a marked superinduction of ICAM-1 was observed, while the repressive effect of dexamethasone remained, supporting the hypothesis that dexamethasone acts directly at the transcriptional level.

Antibodies, Monoclonal↗