Human eosinophils have prolonged survival, enhanced functional properties, and become hypodense when exposed to human interleukin 3

Releasability of human hypereosinophilic eosinophils is related to the density of the cells

The activity of eosinophils and neutrophils with respect to the release of granule proteins was studied in 11 patients with the hypereosinophilic syndrome (HES). Granulocytes or purified eosinophils were stimulated with serumopsonized Sephadex particles (C3b-induced release), and the released amounts of eosinophil cationic protein (ECP), eosinophils protein-X (EPX) and myeloperoxidase (MPO) were measured by means of specific radioimmunoassays (RIA). Eosinophils obtained from patients with HES released significantly more ECP (P < 0.002) and EPX (P < 0.01) after 20 min of incubation than cells from the control group. The cellular content of ECP and EPX in eosinophils obtained from the patients with HES was significantly reduced to 50% and 62%, respectively, of the content of these granule proteins of eosinophils from the control group. In separated eosinophils light-density eosinophils released more of both ECP and EPX than normal density eosinophils. There was no difference in MPO release between the patients and the control group. We conclude that the eosinophils from patients with HES have an increased propensity to release their granule proteins and the releasability seems to be related to the density of the cells.

1,1'-Ethylidenebis(tryptophan) (Peak E) induces functional activation of human eosinophils and interleukin 5 production from T lymphocytes: association of eosinophilia-myalgia syndrome with a L-tryptophan contaminant

This study was designed to clarify the important association between eosinophilia-myalgia syndrome (EMS) and the L-tryptophan contaminant, "Peak E." To determine the functional activation of eosinophils induced by Peak E, eosinophil cationic protein (ECP) release was examined. Peak E augumented the release of ECP from peripheral blood normodense eosinophils by degranulation. Proliferative analysis using the human eosinophilic leukemia cell line EoL-3 showed prominent cellular replication in the presence of Peak E. Moreover, Peak E upregulated interleukin 5 (IL-5) receptor levels on normodense eosinophils. Of particular interest, Peak E-stimulated human splenic T cells produced bioactive and immunoreactive IL-5. Marked induction of IL-5 mRNA in Peak E-stimulated T cells was also shown by reverse-transcriptase polymerase chain reaction (RT-PCR). In contrast, L-tryptophan without the contaminant showed none of these effects. Thus, these data suggest that Peak E might be involved in the pathogenesis of EMS through bimodal mechanism including IL-5 generation by T cells and potentiation of eosinophil functional activation.

Leukotriene B4 induces interleukin 5 generation from human T lymphocytes

Leukotriene B4 (LTB4) has been shown to affect several interleukin (IL)-linked functions of human lymphocytes. In this study, we investigated whether LTB4 regulates IL-5 generation from human T cells and subsequently modulates eosinophil functions. Preincubation of T cells with very low concentrations (10(-12) to 10(-8) M) of LTB4 induced concentration-dependent IL-5 production, the event occurring after the first 24 h of cultivation. However, direct action of LTB4 to IL-5 generation is strictly dependent on a preincubation with appropriate concentration of LTB4. In contrast, the stereoisomer of LTB4, 5S,12S-dihydroxy-6,8,10,14-eicosatetraenoic acid showed no enhancement of IL-5 production. IL-5 released from LTB4-primed T cells elicited sustained viability of mature eosinophils and reduced the content of eosinophil cationic protein in their crystalloid matrix by degranulation. These data suggest that LTB4 induces bioactive IL-5 production from T cells and that the released IL-5 modulates eosinophil functions which might play a crucial role in eosinophil-linked allergic inflammatory process.

Characterization and pharmacological modulation of antigen-induced peritonitis in actively sensitized mice

1. The intraperitoneal (i.p.) injection of 1 or 10 micrograms ovalbumin to sensitized Balb/c mice led to an acute histamine release, firstly evidenced 1 min after the challenge and returning to basal levels 30 min thereafter. This phenomenon was unaccompanied by protein extravasation. A dose-dependent increase in the amounts of immunoreactive leukotriene (LT) C4 and LTB4 was observed in the peritoneal washing from sensitized mice 6 h after 1 or 10 micrograms ovalbumin administration. In separate experiments, the i.p. administration of 1 mg activated zymosan to non-immunized mice was followed by a marked protein extravasation, and by immunoreactive LTC4 and LTB4, but not histamine, release in mouse peritoneum 1 h after its injection. 2. Mediator release in the mice peritoneal cavity was concomitant with a transient neutrophil infiltration, which peaked at 6 h and returned to basal levels therefore. An intense eosinophil accumulation starting at 24 h, peaking at 48 h and returning to basal values at 164 h, was also observed. 3. Ovalbumin (1 microgram)-induced eosinophilia, observed at 24 h, was reduced by the pretreatment of the animals with dexamethasone (1 mg kg-1, s.c.) or with the 5-lipoxygenase inhibitor, BWA4C (20 mg kg-1, s.c.), whereas indomethacin (2 mg kg-1, s.c.) and the platelet-activating factor (PAF)-antagonist SR 27417 (10 mg kg-1, s.c.) were ineffective. These results indicate that metabolites of arachidonic acid of lipoxygenase pathway, but not cyclo-oxygenase derivatives or PAF, mediate antigen-induced eosinophil accumulation in the mouse peritoneum. 4. The histamine HI receptor antagonist drug, cetirizine (15-30 mg kg-1, s.c.) markedly reduced ovalbumin-induced eosinophil accumulation under conditions where terfenadine was ineffective, suggesting that the effect of cetirizine was not related to the inhibition of the H1 receptor effects of histamine.5. The immunosuppressive agent, FK-506 (1-2 mg kg-1, s.c.) and the protein synthesis inhibitor,cylcoheximide, when administered either in situ (0.06 ng/cavity) or systemically (5 mg kg-1, s.c.),prevented antigen-induced eosinophil accumulation in the mouse peritoneum, contributing to the concept that substances (probably cytokines) originating from lymphocytes may be involved in the modulation of the eosinophilotactic response in this model.6. The results of the present study indicate that the i.p. administration of ovalbumin to actively sensitized mice induced late eosinophil accumulation in the peritoneal cavity. This phenomenon, which may be in part mediated by the release of lipoxygenase metabolites and/or by newly generated factors,such as T-lymphocytes-derived eosinophilotactic cytokines, offers an interesting tool to investigate the mechanism of action of anti-allergic and anti-inflammatory drugs.

Eosinophil adhesion and maturation is modulated by laminin

Eosinophils (Eo) participate in the inflammatory response to parasites, allergins, toxins, and epitopes recognized by autoimmune antibodies. Nonetheless, little attention has heretofore been paid to the interactions of Eo with extracellular matrix (ECM) proteins during their migration through the subendothelial basement membrane and into the surrounding tissue. Therefore, we have studied the adhesion of Eo to specific ECM proteins and the effect of this adhesion on Eo viability and maturation. Control Eo (from normal donors) adhere no better to substrates coated with laminin (LM), fibronectin (FN), cytotactin (CT), or collagen types I or IV (Col IV) than they do to human serum albumin coated substrates. In contrast, Eo activated in vitro with IL-5 or in vivo in patients with eosinophilia bind well to LM, FN and Col IV. LM is by far the most avid ligand among these molecules. For example, 43% of input cells bind to a substrate bearing 200 fmol/cm2 of LM; a similar level of adhesion to FN requires 30 times as much absorbed protein. Antibody inhibition experiments suggest that the alpha 6 beta 1 integrin heterodimer is the predominant LM receptor on these cells. Flow cytometry showed similar levels of these subunits on control and activated Eo, suggesting that Eo adhesion to LM is not regulated simply by cell surface integrin concentration. The effects of ECM proteins on Eo behavior were also examined. A LM-coated substrate (with no added cytokine) was found to be almost as effective as IL-5 in maintaining Eo viability while an equally adhesive FN-coated substrate had much less effect. Normally, even in the presence of 10% serum, no Eo survive a 5-day incubation in vitro unless IL-3, IL-5, or GM-CSF is added to the medium. Conditions that inhibit adhesion to LM (anti-integrin antibodies in the medium or CT on the substrate) and certain anti-cytokine antibodies inhibited the promotion of Eo viability by LM. During incubation on LM, Eo become hypodense, as they do in the presence of IL-5, indicating that they have become activated. These observations suggest that the interactions of Eo and ECM proteins may be important both for their potential to direct Eo migration and for their ability to regulate Eo viability, cytokine production, and maturation.

IL-5 in post-traumatic eosinophilic pleural effusion

Thoracic trauma or pneumothorax can result in pleural fluid eosinophilia. In this study we investigated the role of the eosinophilopoietic cytokine IL-5 in three cases of post-traumatic eosinophilic pleural effusions (EPE). Using a specific immunoenzymatic assay, significant levels of IL-5 were found in EPE (range 100-3000 pg/ml), while IL-5 was undetectable (< 25 pg/ml) in corresponding serum samples and in non-eosinophilic pleural fluids. IL-5 present in pleural fluids was found bioactive in a proliferative assay using a mouse CTLL-2 cell line transfected with the cDNA corresponding to the alpha chain of the human IL-5 receptor. Using a reverse polymerase chain reaction (PCR) method, we found IL-5 mRNA expression within pleural mononuclear cells from patients with EPE, but not in corresponding peripheral blood mononuclear cells (PBMC), confirming that IL-5 is synthesized locally in the pleural cavity. In the two cases in which pleural CD4+ cells were purified, these cells were identified as the major source of IL-5. Taken together, these data indicate that the development of post-traumatic EPE is related to a local secretion of IL-5 by CD4+ cells present in the pleural cavity.

Detection of GM-CSF in asthmatic bronchial epithelium and decrease by inhaled corticosteroids

The presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) in airway epithelial cells in vivo was assessed in 15 asthmatic and 9 normal subjects. GM-CSF was analyzed using immunohistochemistry with a polyclonal and a monoclonal antibody. Hue saturation intensity color image analysis was used to quantify staining. Asthmatic airway epithelial cells stained significantly more with anti-GM-CSF than those from normal subjects (p = 0.0013 and p = 0.0003 for the polyclonal and monoclonal antibodies, respectively). Additionally, 8 asthmatic individuals inhaled 1,000 micrograms beclomethasone diproprionate per day for 8 wk and 6 asthmatic patients inhaled matching placebo. There was a significant reduction of GM-CSF in the epithelium in the patients who were given corticosteroids (p = 0.014), whereas the group of subjects who were given placebo showed no significant change in GM-CSF staining. There was a correlation between the percentage suppression of GM-CSF staining by inhaled corticosteroids and the percentage increase in FEV1 (r = 0.61, p < 0.05) and percentage decrease in carbachol responsiveness (r = 0.80, p < 0.01). These findings suggest that GM-CSF may play a role in the inflammatory processes of bronchial asthma and that the epithelial cell may be a target cell for drug action.

Mechanism of airway inflammation in asthma

Airway inflammation has emerged as an important contributor to mechanisms of asthma. Furthermore, the presence of airway inflammation is present even in the absence of severe symptoms. To study the mechanisms by which bronchial inflammation can occur in asthma, a number of models have been developed including the airway response to antigen in allergic subjects. The pattern that has emerged from such studies indicates prompt pulmonary mast-cell activation and the apparent initiation of an inflammatory response. This inflammatory response develops over hours and is important in the later and more persistent development of bronchial obstruction. The eosinophil is an important cell in this process as are proinflammatory cytokines generated from activated lung mononuclear cells. The consequence of this multiple cell, multiple proinflammatory product interaction is the establishment of a self-perpetuating, redundant process by which asthma severity increases.

Pharmacological modulation of lipopolysaccharide-induced pleural eosinophilia in the rat; a role for a newly generated protein

Intrathoracic injection of endotoxin lipopolysaccharide, LPS into rats induced a dose-dependent increase in the number of eosinophils recovered from the pleural cavity. The pleural eosinophil accumulation peaked within 24-48 h, and returned to basal levels within 120 h. This phenomenon was accompanied by mononuclear cell infiltration, and preceded by massive neutrophil accumulation. Pretreatment with indomethacin, BW 755C (a dual cyclo/lipoxygenase inhibitor), BW A4C (a specific lipoxygenase inhibitor) or the platelet activating factor (PAF) antagonists WEB 2086 and PCA 4248 failed to inhibit the endotoxin-induced pleural eosinophilia, whilst dexamethasone (5-10 micrograms/cavity) or cycloheximide (14-28 micrograms/cavity) abolished this phenomenon. Transfer of the cell-free pleural washing from LPS-treated donor rats to normal recipient rats led to a two-fold increase in the eosinophil counts. Treatment of donors, but not recipients, with cycloheximide or dexamethasone inhibited the eosinophil accumulation induced by the pleural washings, indicating that the generation of the eosinophilotactic activity, but not its effects, depends on protein synthesis. This eosinophilotactic activity was maintained after lyophilization and heating (100 degrees C for 30 min), but was destroyed by trypsin. This substance has a molecular weight ranging between 10 and 50 kDa. The available data suggest that the late eosinophil accumulation induced by LPS is independent of arachidonic acid metabolites and PAF, and probably depends on a newly generated heat-stable soluble protein.

Production of IL-3 by non-transformed primary neonatal murine keratinocytes: evidence for constitutive IL-3 gene expression in neonatal epidermis

Interleukin 3 (IL-3) is a cytokine produced by activated T lymphocytes that is best understood as a hematopoietic growth and differentiation factor. Production of IL-3 by other cell types is controversial; while certain transformed non-lymphocyte cell lines can produce IL-3, it is generally assumed that their non-transformed counterparts do not. It has been previously reported that Pam 212, a transformed murine keratinocyte cell line, produces IL-3. In this study we report that IL-3 can also be secreted by normal murine keratinocytes. Using a cell line (FL5.12) which is responsive to IL-3 and not to other keratinocyte derived cytokines, (e.g. GM-CSF, IL-1 and IL-6), we tested conditioned media from cultures of normal neonatal keratinocytes for biologically active IL-3. These media stimulated the proliferation of FL5.12, and the effect could be neutralized by specific antibodies to IL-3. The presence of IL-3 mRNA was demonstrated by polymerase chain reaction (PCR) amplification of reverse transcribed IL-3 mRNA from cultured normal neonatal keratinocytes and confirmed by Southern blot analysis. By similar techniques, IL-3 mRNA could be identified in freshly isolated neonatal epidermis but not dermis. These data indicated that IL-3 is produced by keratinocytes in the skin of normal neonatal mice, raising the likelihood that the neonatal epidermal microenvironment may have hematopoietic or lymphopoietic properties.

In vitro anti-tumor activity of eosinophils from cancer patients treated with subcutaneous administration of interleukin 2. Role of interleukin 5

Interleukin 2 (IL-2) administration is known to induce marked eosinophilia. To evaluate the potential role of eosinophils as anti-tumor effectors and to understand the direct or indirect effects of IL-2 on eosinophils, the physical and functional characteristics of eosinophils obtained during IL-2 therapy were compared with those of eosinophils obtained from the same patients before IL-2 administration, or from healthy donors. The treatment schedule consisted of subcutaneous (s.c.) injections of IL-2, and was performed in 7 patients with small-cell lung cancer (SCLC) in advanced stage. A marked increase of hypodense cells in peripheral blood was found to correlate with eosinophil activation in patients undergoing IL-2 therapy. Cytotoxic activity of eosinophils against allogeneic tumor cells (SCLC, K562 and melanoma lines), as assessed by direct and antibody (Ab)-dependent cellular cytotoxicity (ADCC), was markedly increased during IL-2 therapy. Conversely, eosinophils obtained before treatment, like those of healthy donors, lacked any activity against tumor cells. Sera from IL-2-treated, but not from untreated, patients, significantly improved the in vitro survival and anti-tumor cytotoxicity of eosinophils from healthy donors. Comparable effects were obtained with eosinophils cultured with interleukin 5 (IL-5), granulocyte-macrophage colony-stimulating factor (GM-CSF) and, to a lesser extent, by tumor necrosis factor-alpha (TNF alpha), while no direct activity was mediated by IL-2. A 91% inhibition of eosinophil ADCC was found after pre-incubation of the sera of IL-2-treated patients with anti-IL-5 but not with anti-GM-CSF or anti-TNF alpha Ab. IL-5 mRNA expression was detected in peripheral-blood lymphocytes (PBL) obtained 4 hr after IL-2 injection during the second and third week of IL-2 therapy. Phenotypic analysis of eosinophils from IL-2-treated patients showed enhanced expression of activation markers, including Fc gamma RII (CD32), HLA-DR, CR3 (CD11b) and CRI (CD35). These findings suggest that a significant cytotoxicity against tumor cells can be mediated by eosinophils after indirect, IL-5-mediated in vivo activation by IL-2, and that eosinophils may be involved in the anti-tumor response(s) induced in vivo by IL-2.

Lack of increased numbers of low-density eosinophils in the circulation of asthmatic individuals

The density distribution pattern of eosinophils over discontinuous isotonic Percoll gradients from the blood of normal, asymptomatic allergic and non-allergic asthmatic individuals was investigated. There was a completely identical distribution pattern between the investigated groups. Analysis of the expression of surface markers for complement receptors CR1 and CR3 and immunoglobulin G receptor on eosinophils derived from the density bands 1.080, 1.085 and 1.090 g/ml supported this finding since they did not reveal differences in expression between the bands within one group but also not between the three groups. Eosinophils of the various density bands were further purified and stimulated in vitro to produce leukotriene C4 (LTC4) by the calcium ionophore A23187 or serum treated zymosan. Equal amounts of LTC4 were synthesized by the eosinophils of the various density bands within one group. However, it appeared that the eosinophils of all density bands of allergic and non-allergic asthmatics synthesized significantly more LTC4 than the eosinophils from normal individuals (five- to tenfold). Probably this indicates in vivo priming of the eosinophils in asthmatic individuals which is not reflected by a change in density. Control experiments, dealing with possible artifacts due to the isolation procedure or the patient selection, to find differences in distribution patterns over discontinuous Percoll density gradients of the eosinophils of asthmatic compared to normal individuals failed to show such a difference. Therefore, the density distribution pattern of eosinophils over these gradients does not reflect cell activation, whereas LTC4 formation clearly does. This could mean that LTC4 formation is a more sensitive parameter for cell activation than density distribution or cell surface marker expression.

Eosinophils infiltrating interleukin-5 gene-transfected tumors do not suppress tumor growth

Tumor-associated eosinophils have been observed in human tumors and in experimental tumor models, but their function is poorly understood. To study the role of eosinophils during tumor growth, the plasmacytoma J558L and the mammary adenocarcinoma TS/A were transfected with an expression vector encoding the murine gene for interleukin-5 (IL-5), a cytokine inducing proliferation and activation of eosinophils. Injection of parental cells, mock-transfectants and IL-5-producing cells into syngeneic mice showed that local IL-5 secretion induced rapid tumor infiltration by eosinophils, as evidenced by immunohistochemical staining, but nevertheless did not alter the tumor growth kinetics of IL-5 transfectants. Therefore, the mere presence of IL-5 and eosinophils was not sufficient to induce a protective host immune response.

IL-5 is the predominant eosinophil-active cytokine in the antigen-induced pulmonary late-phase reaction

The mechanism of airway eosinophilia during antigen-induced inflammation was investigated by measurement of eosinophil-active cytokines utilizing an eosinophil survival assay. In the first study, 4 patients with allergic rhinitis underwent segmental bronchoprovocation (SBP) with low, medium, and high doses of ragweed extract instilled into different bronchial subsegments; bronchoalveolar lavage (BAL) fluids were collected from each segment 12 min and 48 h after challenge. Eosinophil granule proteins and eosinophil survival activity were significantly elevated in the 48-h (late-phase) BAL fluids from these segments. Correlations were observed between the concentrations of eosinophil granule proteins and eosinophil survival activity (rs = 0.717 to 0.880, p < 0.001) in BAL fluids. Eosinophil survival activity was completely neutralized by anti-IL-5 monoclonal antibody in five of the seven 48-h samples tested representing three of the 4 patients. In the two remaining samples, eosinophil survival activity was only partially neutralized by either anti-IL-5 antibody or anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) but was completely neutralized by anti-IL-5 and anti-GM-CSF in combination. Subsequently, in the second study, 10 patients with allergic rhinitis were challenged by SBP with ragweed extract. Eosinophil survival activity was significantly elevated in the 48-h BAL fluids; this activity was partially neutralized by anti-IL-5 antibody about (48%) and completely neutralized by the combination of anti-IL-5 and anti-GM-CSF antibodies. These findings suggest that the eosinophil survival activity in the late inflammatory lesions following SBP with allergen is mainly associated with IL-5, with small contributions from GM-CSF.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

T cells and eosinophils in the pathogenesis of asthma

Persistent asthma is characterized by chronic inflammation of the bronchial mucosa, where T cells and eosinophils are prominent. This article summarizes the evidence that asthmatic bronchial inflammation is initiated and propagated by cytokines secreted by activated T cells and other cells, and describes how the release of specific cytokines could result in local preferential accumulation and activation of eosinophils.

Increases in activated T lymphocytes, eosinophils, and cytokine mRNA expression for interleukin-5 and granulocyte/macrophage colony-stimulating factor in bronchial biopsies after allergen inhalation challenge in atopic asthmatics

Immunohistology and in situ hybridization were used to evaluate the presence, activation status, and cytokine mRNA profile of cells in the bronchial mucosa during human allergen-induced asthma. Fifteen atopic asthmatic subjects underwent inhalation challenge with allergen and with allergen diluent, performed in random order separated by an interval of at least 3 wk. Bronchial biopsies were obtained 24 h after challenge. Immunostaining revealed increases in the numbers of secreting eosinophils (EG2+; P < 0.05) and in interleukin-2 receptor (IL-2R)-positive cells (CD25+; P < 0.01) after allergen compared with diluent challenge. No differences were observed in the numbers of total leukocytes (CD45+), T lymphocytes (CD3+, CD4+, and CD8+), elastase-positive neutrophils, macrophages (CD68+), or mast cell subtypes (MCT+ or MCTC+). In situ hybridization revealed significant increases in the numbers of cells expressing mRNA for IL-5 (P < 0.02) and granulocyte/macrophage colony-stimulating factor (P < 0.01) after allergen compared with diluent challenge. A significant inverse relationship was observed between the number of cells expressing mRNA for IL-4 and for interferon-gamma (r = -0.75, P < 0.02). The results support the view that cytokines possibly from activated T lymphocytes may contribute to local eosinophil accumulation during allergen-induced asthma.

Allergic inflammation

A greater understanding of the basic mechanisms of allergic inflammation is pertinent to the development of new treatments. Previous studies have focused on the role of mediators of hypersensitivity and effector cells, including mast cells and eosinophils. Recent evidence suggests that IgE-dependent activation and tissue eosinophilia are under the local regulation of distinct cytokines. Originally described as products from T lymphocytes, these peptide messengers are produced by alternative cells, including mast cells, eosinophils and the respiratory epithelium. In vitro studies in murine models and using cloned human T lymphocytes indicate the preferential production of "Th2-type" cytokines, including interleukin-4 (IL-4) and IL-5. This review considers the evidence from in vivo studies in humans that "Th2-type" cytokines have a primary role in orchestrating both IgE-dependent events and local tissue eosinophilia. Novel therapeutic approaches might include a broad strategy directed against T lymphocytes, including the use of immunosuppressive agents or anti CD4 antibodies or more precise targeting of IL-4 and/or IL-5.

Eosinophils and cytokines

Cytokines act on eosinophils to regulate eosinophil function, with IL-5 recognised to be especially important in control of eosinopoiesis, eosinophil survival and eosinophil priming. In addition, eosinophils have the capacity to produce cytokines involved in acute and chronic inflammatory and repair processes, as well as to produce cytokines that stimulate eosinophils within an autocrine loop. This paper describes (A) an immunomagnetic selection technique for the purification of human blood eosinophils, and (B) a method that employs immunofluorescence with flow cytometry for measurement of blood and sputum eosinophil surface markers. Having demonstrated that sputum eosinophils express HLA-DR, highly purified blood eosinophils were used to analyse (C) the induction and function of eosinophil HLA-DR. Cytokines have the capacity to induce eosinophil HLA-DR, and are produced by eosinophils as an accessory function during antigen presentation. Finally, preliminary data on (D) eosinophil production of IL-8 is presented. Hence, eosinophils have the capacity to act as immunomodulatory cells within cells networks in allergic and asthmatic inflammation.

Modulation of eosinophil chemotaxis by interleukin-5

Eosinophilia and eosinophil function are regulated by cytokines such as granulocyte/macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and interleukin-5 (IL-5). We have investigated the modulatory role of IL-5 on N-formyl-methionyl-leucyl-phenylalanine (FMLP), neutrophil-activating factor (NAF/IL-8), platelet factor 4 (PF4), and cytokine-induced chemotaxis of eosinophils from normal individuals. These eosinophils show a small chemotactic response toward PF4 but not to NAF/IL-8 and FMLP. Preincubation of eosinophils with low concentrations of IL-5 caused significantly increased responses toward PF4 and induced a significant chemotactic response toward FMLP and NAF/IL-8. In marked contrast, IL-5 (or IL-3) priming of eosinophils from normal donors resulted in a strong inhibition of GM-CSF-induced chemotaxis. A similar decrease in the chemotactic response toward GM-CSF was observed in eosinophils derived from allergic asthmatic individuals. This finding suggests that the latter eosinophils may have had a prior exposure to IL-5 (or IL-3). Washing of the cells after priming did not abrogate the inhibition of the GM-CSF response. Our data indicate that at low concentrations IL-5 is an important modulator of eosinophil chemotaxis, causing selective upregulation or downregulation of chemotactic responses toward different agents.

Interleukin-3-induced up-regulation of CR3 expression on human eosinophils is inhibited by dexamethasone

Eosinophil function is regulated by several cytokines, including interleukin-3 (IL-3), IL-5 and granulocyte-macrophage colony-stimulating factor (GM-CSF). Culture of human eosinophils with IL-3 produced a marked, dose-dependent up-regulation of CR3 expression. This was maximal after 1 day in culture and dependent on protein and RNA synthesis, as demonstrated by inhibition with cycloheximide and actinomycin D, respectively. IL-5 and GM-CSF had a similar effect on eosinophil complement receptor type 3 (CR3) expression, but the maximal response to IL-5 was always less than to IL-3 or GM-CSF. Dexamethasone inhibited the Il-3-induced up-regulation of CR3 expression in a dose-dependent manner, with an IC50 of 5 x 10(-8) M. This study demonstrates the effect of IL-3, IL-5 and GM-CSF on eosinophil CR3 expression and confirms the capacity of eosinophils to modify their phenotype through de novo protein synthesis. This process could be inhibited by physiological concentrations of glucocorticoids, thus providing an additional mechanism for their mode of action in allergic disease.

The interleukin 2 receptor in the hypereosinophilic syndrome

The hypereosinophilic syndrome (HES) has been previously described as a clinicobiological entity characterized by a blood eosinophil count of over 1.5 x 10(9)/L of unknown cause associated with several clinical complications. In reality, HES is a heterogeneous group of diseases with variable and unpredictable progress in visceral lesions, thought to be related to the deleterious effects of tissue eosinophil infiltration. Various criteria for discrimination between benign and severe forms of HES have been described. These previous retrospective clinical investigations, using biological and clinical markers, have defined different stages of HES. It appears more relevant, however, to consider elements of disease activity by studying mechanisms of induction of persistent hypereosinophilia. The T-cell dependence of blood eosinophilia has led us to evaluate various markers of T-cell activation in particular. In the present review, we report previous results and perspectives suggested by the study of the interleukin 2 receptor in HES.

Effects of cytokines on human basophil chemotaxis

Basophil chemotactic activity (BCA) of eight recombinant human (rh) cytokines was examined. Highly purified basophils were obtained by Percoll discontinuous gradients, followed by negative selection using flow cytometry. Then BCA was measured by means of modified Boyden chamber method. Both interleukin (IL)-3 and granulocyte-macrophage colony-stimulating factor (GM-CSF) had much more potent BCA than complement C5a, leukotriene B4 and platelet activating factor, well known as granulocyte chemotactic factors. Chemotaxis rather than chemokinesis was shown in chequerboard analysis of basophil migration induced by IL-3 and GM-CSF. Relatively high concentrations of IL-5 also induced basophil migration, although predominantly chemokinetic. IL-8 had apparent BCA, which was not so high as that of C5a. In contrast, IL-2, IL-4, interferon(IFN)-gamma and granulocyte colony-stimulating factor (G-CSF) had no significant BCA. These findings suggest that IL-3, IL-5, GM-CSF and, perhaps, IL-8 have an effect on basophil migration as well as modulation of basophil mediator release and may provide some insight into the basophil accumulation observed in late-phase allergic responses.

Structure-function relationships of interleukin-3. An analysis based on the function and binding characteristics of a series of interspecies chimera of gibbon and murine interleukin-3

IL-3 is a glycoprotein cytokine involved in the hematopoietic response to infectious, immunologic, and inflammatory stimuli. In addition, clinical administration of recombinant IL-3 augments recovery in states of natural and treatment-related marrow failure. IL-3 acts by binding to high affinity cell surface receptors present on hematopoietic cells. To determine the site(s) at which IL-3 binds to it receptor, we analyzed a series of interspecies chimera of the growth factor for species-specific receptor binding and biological activity. The results suggest that IL-3 binds to its receptor and triggers a proliferative stimulus through two noncontiguous helical domains located near the amino terminus and the carboxy terminus of the molecule. To corroborate these findings, we have also mapped the binding epitopes of 10 mAb of human or murine IL-3, and have defined four distinct epitopes. Two of these epitopes comprise the amino-terminal receptor binding domain. A third epitope corresponds to the carboxy-terminal receptor interactive domain, and the fourth epitope, apparently not involved in the interaction of IL-3 and its receptor, lies between these sites. And on the basis of sandwich immunoassays using pairs of these mAbs, the two receptor interactive regions appear to reside in close juxtaposition in the tertiary structure of the molecule. These results provide a correlation of the structure-function relationships of IL-3 that should prove useful in evaluating the details of IL-3-IL-3 receptor interaction and in the rational design of clinically useful derivatives of this growth factor.

Protective effects of cyclophosphamide, cyclosporin A and FK506 against antigen-induced lung eosinophilia in guinea-pigs

A close association has been recognized between activated T cells and eosinophils in asthma, albeit circumstantial. The present study attempted to investigate this relationship in an animal model of lung eosinophilia using the new generation of T cell-selective immunosuppressants, cyclosporin A and FK506, compared with the myelotoxic immunosuppressive agent cyclophosphamide. Antigen challenge of ovalbumin-sensitized guinea-pigs resulted in a lung eosinophilia which was assessed by bronchoalveolar lavage. All three agents caused a marked suppression of lung eosinophilia at 24 h post-challenge when the compounds were administered at the time of sensitization but not when administered for 3 days before lavage. However, the lung eosinophilia at 72 h post-challenge was reduced significantly by FK506 and by cyclophosphamide, but not by cyclosporin A, when the drugs were administered for 3 days, before lavage. These results strongly suggest the involvement of T cells in antigen-induced late phase (72 h) eosinophilia in guinea-pigs but not at 24 h. The effects of cyclophosphamide were always associated with a reduction in circulating white cell counts, whereas cyclosporin A and FK506 showed no myelotoxic properties. These results suggest the potential therapeutic use of selective, non-cytotoxic immunosuppressive agents in asthma.

Occurrence and characteristics of hypodense eosinophils in rats infected with Trichinella spiralis

Hypodense eosinophils are observed in peripheral blood and tissue from patients with eosinophilia due to helminthic infections. In this study, the variation in eosinophil density was examined in rats during Trichinella spiralis infection. Hypodense eosinophils were observed in the peripheral blood in association with Trichinella infection. In peritoneal fluid, which was representative of tissue fluid, a majority of eosinophils were hypodense regardless of the infection. During the course of tissue eosinophilia after the infection, there was a particular increase in the lowest dense cells in the population of hypodense eosinophils. Eosinophils with lower density, demonstrated larger diameters and had more potent cytotoxic activity.

Cytokines, platelet activating factor and eosinophils in asthma

Understanding of the pathogenesis of asthma has increased considerably during the past few years. These advances were possible through scientific progress in three areas which contribute to this complex and multifaceted disease: (a) the much clearer understanding of eosinophil function; (b) the defining of lipid mediators in tissue inflammation and bronchial obstruction; and (c) the growing knowledge about the biological action of a new class of protein hormones, collectively called cytokines. In line with this, evidence has accumulated of how these components may interact with each other in providing the basis of inflammatory processes in asthma. Hence it seems appropriate to review the potential implications of this new information for the pathogenesis and therapy of this disease.

Early and late-phase asthmatic reactions: a hypothesis

Why might a foreign particle, exercise or fog inhalation precipitate two asthmatic reactions? It is reasonable to suspect that asthmatic patients develop two reactions because healthy subjects may also develop two physiological responses to the same stimuli. This suggestion is supported by the observation that living things have developed adaptative systems to confront either sudden or persistent changes in the environment or within the internal milieu. The results of several studies suggest that the early phase response (EPR) usually involves cells which are normal residents of the respiratory epithelium (mast cells) and pre-formed substances (histamine), whereas cells participating in the late phase reaction (LPR) are recruited from the circulation (eosinophils, basophils and T cells). Up to now most of the studies of the EPR and LPR have been addressed to detecting a cell or metabolite abnormality. This simplistic approach would probably not improve the knowledge of the mechanisms involved in asthmatic responses. Since the presence of isolated or dual responses seems to depend on the intensity and duration of the stimuli it is reasonable to suspect that EPR and LPR are the result of an excessive adaptative response of the bodies of asthmatics to sudden and prolonged/strong stimuli, respectively.

Immunohistology of the nasal mucosa following allergen-induced rhinitis. Identification of activated T lymphocytes, eosinophils, and neutrophils

We have studied the immunohistology of the nasal mucosa in allergen-induced rhinitis. Sixteen grass pollen-sensitive patients were challenged twice by randomly allocated allergen or control solutions applied on filter paper disks to the inferior turbinate. All had immediate nasal responses, but late-phase responses were equivocal and only evident as nostril blockage. When cell counts in the nasal submucosa were compared with control values 24 h after allergen, there were no changes in CD45+ (total leukocytes), CD3+, or CD8+ cells. Significant increases were found in the numbers of CD4+ T-helper cells (p less than 0.05) and CD25+ [interleukin-2 receptor (IL-2R+)] cells (p less than 0.02). Increases in eosinophils (anti-major basic protein, p less than 0.01) and neutrophils (antineutrophil elastase, p less than 0.01) were also observed. There were increases in tissue macrophages and HLA-DR-positive immunostaining and a reduction in mast cells (tryptase positive), but none of these changes was statistically significant. No significant changes in epithelial thickness, cross-sectional area, or integrity were observed. There was a significant correlation between CD4+ and CD25+ cells (r = 0.61, p less than 0.01) but not between macrophages and CD25+ cells (r = 0.18). The changes in the nasal submucosa were not merely a reflection of alterations in circulating cell populations since it was shown that a significant increase in the lymphocyte CD4/CD8 ratio (p less than 0.05) was observed in nasal biopsies but not in peripheral blood after allergen challenge.(ABSTRACT TRUNCATED AT 250 WORDS)

Inflammation and the allergic response

The atopic diseases--allergic rhinitis, asthma, and atopic dermatitis--are chronic inflammatory diseases characterized by an exacerbating and remitting course and can only rarely be associated causally with allergen exposure. The challenge to ascribe an allergic basis to these diseases is derived from the apparent inability to reconcile these chronic inflammatory features with a process thought to be initiated by the rapid release of mediators after the interaction of allergen with IgE-coated mast cells. The traditional understanding has been that mast cell activation results in the release of a series of preformed and rapidly synthesized substances that mediate the immediate onset of vasodilatation, vascular leakage, smooth muscle contraction, and irritant nerve receptor stimulation. These mediators, however, are rapidly degraded and are not thought to be associated with a significant inflammatory component. Recent studies, however, have established that the interaction of allergen with the immune system is, in fact, far more complex (Fig. 4). In addition to mast cell activation, allergen can interact with and activate T-lymphocytes and mononuclear phagocytic cells, leading to the secretion of cytokines and other inflammatory substances. Furthermore, the interaction of allergen with the mast cell may be far more complex, with the potential to stimulate the delayed release of newly synthesized cytokines. The interaction of allergen with the immune system also promotes the secondary release of inflammatory neuropeptides. Thus, the known spectrum of mediators released after allergen exposure has vastly been expanded. These include numerous still uncharacterized chemotactic and activating peptides; eicosanoids such as 5-HETE, 12-HETE, and leukotriene B4; platelet-activating factor; several proteases; neuropeptides and, most importantly, the cytokines. These mediators recruit and activate neutrophils, monocytes, basophils, and eosinophils, attract additional lymphocytes and mononuclear phagocytic cells, and induce mast cell proliferation with further mast cell degranulation. A vicious cycle subsequently develops, with further inflammation and tissue destruction. Thus, the interaction of allergen with the immune system has become a complex cascade capable of producing the chronic inflammatory changes characteristic of allergic diseases.

Selective eosinophil leukocyte recruitment by transendothelial migration and not by leukocyte-endothelial cell adhesion

Eosinophil infiltration is the hallmark of allergic inflammatory events. However, the mechanisms governing the influx of eosinophils into the tissue at a site of an allergic reaction remains unclear. We have examined the interactions of eosinophils and neutrophils isolated from the same atopic donor with cultured human umbilical vein endothelial cell (EC) monolayers in the search for a mechanism for this selective eosinophil recruitment. First, the adherence of eosinophils and neutrophils to ECs stimulated with lipopolysaccharide, interleukin (IL)-1 alpha, and tumor necrosis factor-alpha were compared. Each mediator induced a similar dose-dependent enhancement of eosinophil adhesiveness for both eosinophils and neutrophils. Thus, although cytokine activation of ECs in the vasculature adjacent to an inflammatory site probably serves as an important focusing mechanism for the extravasation of inflammatory cells at this site, there does not appear to be any selective EC-dependent mechanism for eosinophil recruitment. Little or no effect on eosinophil and neutrophil adherence was observed with IL-3, IL-5, granulocyte/macrophage colony-stimulating factor, platelet-activating factor (PAF), leukotriene B4, or histamine. Second, the migration of eosinophils and neutrophils through an EC monolayer in response to chemoattractants was examined. PAF was found to selectively enhance eosinophil transendothelial migration at doses of 10(-7) to 10(-10) M, with optimal effect at 10(-8) M. This effect was gradient dependent and could be inhibited by WEB 2086, a specific PAF inhibitor. These results suggest that localized production of PAF may be a prime factor in the events leading to eosinophil accumulation at allergic inflammatory sites, and that selectivity for eosinophil recruitment occurs at the stage of transendothelial cell migration under the influence of cell-specific chemoattractants.

Characteristics of peripheral blood eosinophils in patients with nocturnal asthma

A number of mechanisms have been proposed to explain nocturnal exacerbations of asthma including circadian patterns in circulating cortisol and catecholamines. These factors may influence airway smooth muscle tone and circulating eosinophil characteristics and function. Because recent evidence has indicated that eosinophils contribute to airway inflammation and the severity of asthma, we evaluated the relationship among peripheral blood eosinophils, their density distribution, and the appearance of nocturnal asthma. Fifteen patients with asthma were evaluated. Spirometry (FEV1 and FVC) was determined at 0400 and 1600, and the number and density distribution of peripheral blood eosinophils were determined. Five patients had nocturnal asthma, defined as a 15% or greater fall in FEV1 at 0400 versus 1600. The patients with nocturnal asthma had greater numbers of eosinophils (cells x 10(6)/ml) at 0400 (0.845 +/- 0.13 versus 0.351 +/- 0.03) and 1600 (0.651 +/- 0.18 versus 0.319 +/- 0.07) and a greater circadian variation with peak eosinophilia at 0400. Furthermore, we found a significant circadian increase in low-density eosinophils (as determined by Percoll density gradient centrifugation) at 0400, but only in patients with nocturnal asthma. These observations suggest that a circadian variation in low density eosinophils may contribute to nocturnal exacerbations of asthma.

Density profile of bronchoalveolar lavage eosinophils in the guinea pig model of allergen-induced late-phase allergic responses

Inhalation of aerosolized ovalbumin by guinea pigs both during sensitization and upon challenge induces a pulmonary eosinophilia as assessed by cells recovered in bronchoalveolar lavage fluid (BALF). In comparison with BALF eosinophil numbers in naive animals of 0.82 +/- 0.2 x 10(6) cells, those in sensitized animals before challenge and 17 and 72 h after challenge were 1.48 +/- 0.2 x 10(6), 2.60 +/- 0.6 x 10(6), and 4.2 +/- 0.7 x 10(6) cells, respectively. BALF eosinophils from all these groups were notable for their heterogeneity with respect to density, size, and appearance under the electron microscope. In comparison with peritoneal eosinophils, which had a single mean density peak of 1.088 +/- 0.001 g/ml, BALF cells comprised hypodense (less than 1.080 g/ml), normodense (1.080 to 1.096 g/ml), and hyperdense (greater than 1.096 g/ml) eosinophils. The percentage of hypodense eosinophils rose from 25% in naive animals to 63% in sensitized animals (P less than 0.001) and fell after challenge. In contrast, challenge induced the appearance of hyperdense eosinophils, which rose from 6% in sensitized animals to 42% 72 h after challenge (P less than 0.001). Blood eosinophils in naive animals showed a similar profile to those in the lung, but after sensitization and challenge no gross changes in the proportion of either hypodense or hyperdense eosinophils were observed. Flow cytometric analysis of BALF eosinophils indicated that hypodense eosinophils, with a mean diameter of 15.8 microns, were larger than both normodense and hyperdense eosinophils, which had mean diameters of 14.3 and 11.6 microns, respectively. Although the numbers and size of granules were not reduced in hypodense BAL eosinophils, electron microscopy morphology indicated a reduced granular content.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin 3 is a growth factor for human follicular B cell lymphoma

More than one-half of adults with non-Hodgkin's B cell lymphomas present with low-grade follicular lymphomas. These tumor cells are found in close association with follicular T lymphocytes and dendritic cells, suggesting that the surrounding cells may play a role in the support of follicular tumors. Supernatants from activated human peripheral blood lymphocytes were found to promote the in vitro proliferation of follicular tumor cells. This effect was entirely due to interleukin 3 (IL-3), a factor generally thought to cause the growth and differentiation of immature hematopoietic cells. IL-3 receptors were detected on fresh isolates of all primary follicular cell tumors examined. These findings suggest that follicular cell tumors may be dependent in vivo on IL-3 and that therapies directed against IL-3, its receptor, or the T cells that produce it may be effective treatment for follicular lymphoma.

Platelet-activating factor primes human eosinophil generation of superoxide

Platelet-activating factor (PAF) is a potent inflammatory mediator that can cause airway obstruction and hyperresponsiveness; these processes are also associated with pulmonary eosinophilia, suggesting a link between these two events. Thus, PAF's interaction with eosinophils may provide a mechanism for airway damage. However, direct in vitro activation of eosinophils by PAF requires concentrations that are likely higher than those achieved in vivo. As a result, we investigated whether lower, more physiologic concentrations of PAF could prime eosinophils for subsequent activation to another receptor-stimulated factor, in this case formylmethionylleucylphenylalanine (FMLP). To test this hypothesis, eosinophils were preincubated (1 and 15 min) with low concentrations of PAF (1 x 10(-8) and 1 x 10(-10) M); this exposure to PAF resulted in enhanced generation of superoxide anion to FMLP stimulation. Moreover, similar concentrations of PAF decreased eosinophil density and increased expression of cell surface CR3 receptors. Finally, low, nonactivating concentrations of PAF (1 x 10(-10) to 1 x 10(-8) M) caused transient increases in eosinophil cytosolic free Ca2+ concentrations. Collectively, these responses are consistent with the hypothesis that short-term exposure to low concentrations of PAF primes eosinophils to cause an enhanced inflammatory response upon subsequent activation to another receptor agonist. The consequences of this PAF-associated phenomenon can produce an enhanced inflammatory response and airway injury.

Cytokine regulation of eosinophil function

The development and function of eosinophils are regulated by a number of cytokines. Three cytokines have major effects on eosinophilopoiesis. Both granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 stimulate the development of eosinophils as well as other leukocytes. Interleukin-5 promotes eosinophil development and terminal differentiation. These three cytokines also effect the functions of mature eosinophils and can prolong their longevity in in vitro culture, enhance their capacity for release of leukotriene C4 (LTC4), augment their capacity for helminthotoxicity and degranulation, and render them less dense ("hypodense") than normal, unactivated eosinophils. GM-CSF can also induce the expression of HLA-DR on mature eosinophils, which can enable eosinophils to serve as antigen-presenting cells in stimulating T-cell responses. A T-cell-derived cytokine, lymphocyte chemoattractant factor (LCF), which stimulates the migration and function of CD4+ lymphocytes and eosinophils, also utilizes CD4 expressed on human eosinophils as its receptor. LCF stimulates eosinophil migration but not degranulation, leukotriene C4 release, or respiratory burst activity. Interleukin-2 is also a potent chemoattractant for eosinophils. Thus, cytokines are involved in both increased production of eosinophils as well as regulation of the functions of mature eosinophils. These functions of mature eosinophils include effector functions and collaborative interactions with lymphocytes and other tissue cellular elements.

The pathobiology of bronchial asthma

Early studies of patients dying from status asthmaticus revealed marked inflammation of the bronchial tree. Subsequent histological studies of the airways and examination of bronchoalveolar lavage fluid of subjects with mild asthma have confirmed the presence of airway inflammation in life. There is epithelial edema and desquamation, subepithelial deposition of collagen and fibronectin, and an inflammatory cell infiltrate in the mucosa. There are increased numbers of activated eosinophils, CD25-positive T lymphocytes, and immature macrophages with the phenotypic characteristics of blood monocytes. An increased expression of HLA class II is present on epithelium, macrophages, and other infiltrating cells. The severity of clinical asthma correlates with several measurements of the severity of the inflammatory response, suggesting a crucial role for airway inflammation in the pathophysiology of the disease. There is considerable interest and research into the mechanisms underlying the pathogenesis and maintenance of the inflammatory response in asthma. The development and maintenance of the inflammatory response in asthma is likely to be a consequence of a complicated interaction between various cells and the mediators they generate. The characterization of an ever-increasing number of cytokines is of particular interest. Interleukin-3, interleukin-5, and granulocyte-macrophage colony-stimulating factor are hematopoietic growth factors that increase the survival of eosinophils in culture and enhance certain eosinophil functions, such as mediator generation and toxicity. Alveolar macrophages derived from asthmatic subjects produce twofold to threefold more GM-CSF than do those from normal control subjects. Using in situ hybridization, the presence of IL-5 mRNA has been demonstrated in bronchial biopsies from asthmatic subjects. Thus IL-3, IL-5, and GM-CSF influence eosinophil function and survival, and may be generated by T lymphocytes and/or alveolar macrophages within the airways in asthma. In addition to these three cytokines, IL-4 and interferon-gamma may be crucial to the regulation of IgE biosynthesis. TNF-alpha and IL-1 are potentially important in the up-regulation of endothelial adhesion molecules. An important step in the recruitment of leukocytes to an inflammatory focus is margination to the vascular endothelium. Our understanding of the molecular events involved in migration of leukocytes to an inflammatory focus has been advanced by the discovery and characterization of a variety of cell adhesion molecules. The potential role of ELAM-1 and ICAM-1 in allergic inflammation is suggested by their up-regulation on vascular endothelium in association with late cutaneous responses to allergen and by their role in certain primate models of asthma.(ABSTRACT TRUNCATED AT 400 WORDS)

Correlation of eosinophilia with clinical response in patients with advanced carcinoma treated with low-dose recombinant interleukin-2 and mitomycin C

On the basis of our clinical findings that the ability of cancer patients to generate lymphokine-activated killer cells became markedly augmented after mitomycin C administration, we designed a treatment regimen comprising mitomycin C 12 mg/m2, i.v. on day 1 and recombinant interleukin-2 700 U/m2 (8000 IU/kg), i.v. every 12 h from day 4 through day 8. The treatment course was repeated at almost 7-day intervals. Altogether 33 patients with advanced carcinoma, including mainly gastrointestinal carcinoma, were treated with this regimen. Of these, 10 had a partial response (PR) and 4 had a minor response (MR). Since eosinophil counts peaked 1 day after either the first or second course of the therapy, the posttreatment values were compared to each pretreatment level, with regard to the clinical antitumor response to this treatment. When patients who showed PR were defined as responders, absolute eosinophil counts and the percentage of eosinophils in responders after both the first and second courses of the therapy were significantly greater than each pretreatment value or the posttreatment level in nonresponders. Further, these findings were almost identical, when both PR and MR were considered to be a true remission and therefore patients who exhibited PR or MR were defined as responders, although the difference between posttreatment levels of eosinophils in responders and nonresponders was not significant at the second course. These results indicate that eosinophilia induced by this treatment correlates with the clinical response to this therapy.