Production and characterisation of monoclonal antibodies to ovine interleukin-5

Monoclonal antibodies (MAbs) were developed against recombinant ovine interleukin-5 (IL-5) produced in the baculovirus expression vector system. One MAb, D11 (isotype IgG1), neutralised the activity of both recombinant and native sources of IL-5 in a biological assay (Baf cell assay) but was only weakly reactive in immunocytochemistry. Conversely, a second MAb, A8 (isotype IgA), successfully detected IL-5 in immunocytochemistry but did not display neutralising activity. The development of these MAbs will enable the assay of ovine IL-5 in vitro and permit studies into the role of hypersensitivity reactions in sheep by neutralisation of IL-5 in vivo.

Interleukin-4 and -13 expression is co-localized to mast cells within the airway smooth muscle in asthma

BACKGROUND

Airway smooth muscle infiltration by mast cells is a feature of asthma and not eosinophilic bronchitis. In asthma, Th2 cytokines have been implicated as playing a critical role in the development of airway inflammation and hyper-responsiveness. Whether inflammatory cells within the airway smooth muscle release these cytokines is unknown.

METHODS

We have undertaken a comparative immunohistochemical study in bronchial biopsies from 14 subjects with asthma, 10 with eosinophilic bronchitis and eight normal controls recruited from two centres.

RESULTS

The median number of IL-4+ cells/mm2 smooth muscle was significantly higher in subjects with asthma than eosinophilic bronchitis and normal controls for both the anti-IL-4 mAb 3H4 (2.4, 0, 0, respectively; P=0.001) and anti-IL-4 mAb 4D9 (1.6, 0, 0, respectively; P=0.02). There were no group differences in the number of IL-5+ cells (P=0.31). In six subjects with asthma, IL-13 expression by cells within the airway smooth muscle was studied. The median (range) of IL-13+cells was 2 (0.9-2.7). Ninety-four percent of the cells expressing IL-4 (3H4), 92% of those expressing IL-4 (4D9) and 100% expressing IL-13 in the airway smooth muscle were mast cells. Fifty-five percent of the mast cells within the airway smooth muscle co-localized to IL-4 (3H4), 29% to IL-4 (4D9) and 17% to IL-13.

CONCLUSIONS

In asthma, IL-4+ and IL-13+ cells were present within the airway smooth muscle and were expressed predominantly by mast cells, suggesting that IL-4 and IL-13 may play an important role in mast cell-airway smooth muscle interactions.

Kinetics of bone marrow eosinophilopoiesis and associated cytokines after allergen inhalation

Allergen inhalation is associated with increased eosinophil/basophil progenitors in bone marrow 24 hours after allergen inhalation. This study examined the kinetics of eosinophilopoiesis in dual (n = 14), compared with isolated early, responders (n = 12). Dual responders, in contrast to isolated early responders, develop significant sputum and blood eosinophilia and prolonged airway hyperresponsiveness. Bone marrow aspirates were taken before and 5, 12, 24, and 48 hours after allergen inhalation. In dual responders, increases in interleukin (IL)-3-responsive progenitors were detected as early as 5 hours after allergen inhalation, and IL-5-responsive progenitors were detected at 12 and 24 hours. No changes were detected in isolated early responders. Bone marrow IL-5 protein levels increased at 12 and 24 hours in dual responders only and these increases correlated with increases in IL-5-responsive progenitors. In addition, bone marrow IFN-gamma levels increased in dual responders at 48 hours. These data demonstrate that, in dual responders, there is allergen-induced activation of an eosinophilopoietic process that is rapid and sustained, and a relationship between increased bone marrow IL-5 levels and increased eosinophil production. We propose that after allergen inhalation, time-dependent changes in cytokine levels in the bone marrow control differentiation of eosinophil/basophil progenitors.

Influence of Carbohydrate Ingestion on Cytokine Responses Following Acute Resistance Exercise

The effect of carbohydrate supplementation (CHO) on interleukin 2 (IL-2) and interleukin 5 (IL-5) secretion following acute resistance exercise was examined in 9 resistance-trained males. Subjects completed a randomized, double-blind protocol with exercise separated by 14 days. The exercise consisted of a high intensity, short rest interval squat workout. Subjects consumed 1.0 g · kg body mass-1 CHO or an equal volume of placebo (PLC) 10 min prior to and 10 min following exercise. Blood was collected at rest (REST), immediately post exercise (POST), and at 1.5 h of recovery (1.5 h POST). Isolated peripheral blood mononuclear cells were stimulated with PHA and assayed for IL-2 and IL-5 secretion. IL-2 secretion was significantly decreased at POST for both the PLC and CHO groups. However, the degree of decrease was less in the CHO group (16%) than in the PLC group (48%), and this difference was statistically significant. These responses were transient, and the values returned to normal by 1.5 h POST. A mild and transient but significant decrease in IL-5 secretion by the PLC group was observed at POST (26%) compared to REST. No significant decrease was observed in IL-5 secretion for CHO from REST to POST (12%). These data support a possible effect of carbohydrate supplementation on IL-2 and IL-5 secretion following high-intensity resistance exercise.

Evidence from the generation of immunoglobulin G–secreting cells that stochastic mechanisms regulate lymphocyte differentiation

Naive B lymphocytes undergo isotype switching and develop into immunoglobulin-secreting cells to generate the appropriate class and amount of antibody necessary for effective immunity. Although this seems complex, we report here that the generation of immunoglobulin G-secreting cells from naive precursors is highly predictable. The probabilities of isotype switching and development into secreting cells change with successive cell divisions and interleave independently. Cytokines alter the probability of each differentiation event, while leaving intact their independent assortment. As a result, cellular heterogeneity arises automatically as the cells divide. Stochastic division-linked regulation of heterogeneity challenges the conventional paradigms linking distinct phenotypes to unique combinations of signals and has the potential to simplify our concept of immune complexity considerably.

Regulatory effects of IL-12 and IL-18 on Onchocerca volvulus- and Entamoeba histolytica-specific cellular reactivity and cytokine profiles

In the present study, the cytokines interleukin (IL)-12 and IL-18 were evaluated for their capacity to modulate and to re-direct in vitro parasite antigen-specific cellular responsiveness in patients exposed to Onchocerca volvulus and Entamoeba histolytica infection. We found that IL-18 was highly capable of reducing parasite antigen-induced IL-10 production by PBMC. In contrast, addition or neutralization of IL-12, also in combination with IL-18 and the interferon-gamma-inducible chemokine IP-10 did not affect IL-10 production. Interestingly, the highest IL-10 levels were measured when IL-18 and IP-10 were both neutralized. Although having no effect on IL-10, IL-12 strongly promoted spontaneous and parasite antigen-driven IFN-gamma production by PBMC, whereas IL-18 was only moderately affecting IFN-gamma release by PBMC re-stimulated with E. histolytica- or O. volvulus-specific antigens. Both IL-12 and IL-18 diminished the cellular production of IL-13, and a synergistic effect was observed when the cytokines were combined. Likewise, neutralization of IL-12 enhanced Entamoeba and Onchocerca antigen-driven IL-13 production, but no further increase of IL-13 was observed, when anti-IL-12 and anti-IL-18 were used together. This study disclosed that IL-18 will significantly down-regulate parasite-specific IL-10 production, whereas IL-12 induced IFN-gamma and inhibited IL-13 production by PBMC from humans exposed to O. volvulus and E. histolytica. Such selective immune-regulatory capacity of IL-12 and IL-18 may comprise an important tool to re-direct polarized cytokine responses towards a balanced Th1/Th2 cytokine profile, which may prevent pathology and promote immunity against helminth and protozoan parasite infections.

Rhinovirus-induced interferon-gamma and airway responsiveness in asthma

The majority of asthma exacerbations are caused by respiratory infections, with rhinovirus (RV) being the most common virus. Recent evidence has suggested that decreased generation of IFN-gamma is associated with more severe colds and delayed elimination of virus. Whether the generation of IFN-gamma also has any relationship to general features of asthma severity has yet to be determined. To evaluate this hypothesis, peripheral blood mononuclear cells from 19 subjects with atopy and asthma were incubated with RV16 for 6 days to determine IFN-gamma and interleukin (IL)-5 production; these responses were then compared with measurements of airflow obstruction and airway responsiveness. RV16-induced IFN-gamma production correlated significantly with the methacholine PD (r = 0.50, p = 0.03), and the ratio of RV16-induced IFN-gamma:IL-5 correlated with % predicted FEV1 (r = 0.53, p = 0.02). In contrast, there were no significant associations between measures of asthma severity and RV-induced IL-5. These findings suggest that a cytokine imbalance with a deficient Th1 response to RV, but not a Th2 response, is associated with measures of asthma severity and support the concept that impaired antiviral responses may be associated with asthma severity.

T-cell responses and hypersensitivity to influenza and egg antigens among adults with asthma immunized with the influenza vaccine

BACKGROUND

The American Lung Association Asthma Clinical Research Centers (ALA-ACRC) reported that the inactivated influenza vaccine is safe for patients with asthma and recommended its use to reduce the morbidity associated with infection.

OBJECTIVE

Because the ALA-ACRC's recommendation would include vaccination of all patients with asthma, including those with severe asthma and first-time vaccinees, we conducted a parallel study to address whether patients with asthma who report bronchospasm after vaccination might be demonstrating a hypersensitivity response to the vaccine.

METHODS

Thirty-two adult patients with asthma from the ALA-ACRC cohort were recruited. Subjects were randomly assigned to receive influenza vaccine or placebo and then recorded asthma symptoms and peak expiratory flow rates for 14 days. On day 14, influenza vaccine and egg antigen-induced mononuclear cell proliferation and IFN-gamma, IL-5, and IL-4 production were measured and compared with symptoms.

RESULTS

Increased influenza but not egg antigen-induced mononuclear cell proliferation was present among vaccinated subjects. These responses were unrelated to asthma exacerbations after vaccine. There were no differences in cytokine production in response to either influenza or egg antigen in association with asthma exacerbations.

CONCLUSIONS

Episodes of bronchospasm after influenza vaccination do not seem related to hypersensitivity to the vaccine.

Excretory-Secretory Products Secreted by Paragonimus westermani Delay the Spontaneous Cell Death of Human Eosinophils through Autocrine Production of GM-CSF

BACKGROUND

Eosinophils play important roles in tissue inflammatory responses associated with helminth infections. Excretory-secretory products (ESP) produced by tissue-invasive helminths contain a large quantity of proteolytic enzymes that can modulate the host's immune responses. However, little is known regarding the roles of worm-derived products that are responsible for eosinophilic inflammatory responses in helminth infections.

OBJECTIVE

In the present study, we investigated whether ESP produced by Paragonimus westermani, which cause pulmonary or extrapulmonary paragonimiasis in human beings, regulates both cell survival and death of human eosinophils.

METHODS

The ESP was obtained from P. westermani newly excysted metacercariae (PwNEM). Eosinophils were purified from peripheral blood of healthy donors, and the purified eosinophils were incubated with or without the ESP secreted by PwNEM. The viability of eosinophils was assessed by staining with propidium iodide using the flow cytometer.

RESULTS

When eosinophils were incubated with a low concentration of the ESP produced by PwNEM, which totally consists of proteolytic enzymes, eosinophil cell death was delayed compared with results for cells incubated with medium alone. In fact, the ESP at a low concentration stimulated eosinophils to produce detectable levels of GM-CSF that can delay eosinophil cell death. In contrast, eosinophil cell death was dose-dependently accelerated when cells were incubated with high concentrations of the ESP. To see whether the dose-dependent biphasic survival effect of the ESP on eosinophils is primarily due to the protease activity contained in the ESP, a high dose of the ESP was treated with heat at 56 degrees C for 30 min before being added to eosinophils. Attenuating protease activity in a high dose of the ESP by heat treatment reversed the ESP-afforded eosinophil cell death. This prolonged survival of eosinophils induced by the heated ESP was remarkably inhibited by anti-GM-CSF-neutralizing mAb and Jak2 kinase inhibitor AG-490.

CONCLUSION

These results suggest that the proteases in the ESP secreted by PwNEM are able to regulate eosinophil survival through the autocrine production of GM-CSF. Thus, the enhanced eosinophil survival induced by Paragonimus-secreted products may contribute to the elicitation of eosinophilic inflammatory responses at the worm-infected lesion in human paragonimiasis.

Roles of FcgammaRIIB in nasal eosinophilia and IgE production in murine allergic rhinitis

The low-affinity IgG Fc receptor, FcgammaRIIB, displays inhibitory potential in experimental models such as autoimmune diseases. However, whether this receptor is involved in the onset of allergic diseases remains unknown. This study examines the role of FcgammaRIIB in the initiation of allergic rhinitis in mice. Repeated intranasal sensitization with Schistosoma mansoni egg antigen (SEA) induced SEA-specific IgE and marked nasal eosinophilia in high-responder BALB/c mice. FcgammaRIIB gene-deficient (-/-) BALB/c mice displayed severe eosinophilia compared with that of wild-type counterparts. However, FcgammaRIIB -/- mice conversely produced less SEA-specific IgE. The production of interleukin (IL)-4 but not of IL-5 or IFN-gamma by nasal mononuclear cells was also decreased in FcgammaRIIB -/- mice, suggesting that the exacerbation of nasal eosinophila in FcgammaRIIB -/- mice is independent of the local IL-5 levels. The findings in low responder C57BL/6 mice were similar. In addition, nasal eosinophilia in FcgammaRIIB -/- mice passively sensitized with SEA was exacerbated, and conversely, specific IgE production was inhibited after a nasal challenge. These results suggest that FcgammaRIIB plays a regulatory role in the initiation of allergic rhinitis that is independent of either mouse strain or type of sensitization.

Impaired clearance of primary but not secondary Brugia infections in IL-5 deficient mice

Eosinophilia in blood and tissues has been strongly associated with helminth infections for over a century. In vivo depletion of IL-5, a cytokine crucially involved in eosinophilopoiesis with an antibody or through genetic manipulation, reproducibly abrogates helminth-induced eosinophilia, but renders mice permissive only in some models of parasite infection. In the current study, we compared the ability of IL-5(-/-) and B6(+/+) mice to clear intraperitoneal infections with Brugia pahangi L3. IL-5(-/-) mice had statistically significantly higher worm burdens than B6(+/+). This was true for primary infections, in young as well as old mice, suggesting that IL-5 deficient mice are more permissive to Brugian infections. This increase in permissiveness seemed to correlate well with the drastically reduced eosinophil numbers in the peritoneal cavity, the site of infection. In secondary infections, primed IL-5(-/-) mice cleared infections in an accelerated manner, comparable with B6(+/+) mice. These observations suggest that IL-5 induced eosinophilia is more important in the control of a primary infection in naïve mice than a secondary infection in primed mice.

Cloning, expression and biological activity of equine interleukin (IL)-5

The cytokine, interleukin (IL)-5 stimulates eosinophil differentiation, activation and survival and can prime these cells, increasing the response to other mediators. In view of its many effects on eosinophils, IL-5 has been implicated in the pathogenesis of allergic disease in man. Here we report the cloning of equine IL-5 and expression of the recombinant protein by transfection of Chinese hamster ovary (CHO) cells. The cloned cDNA sequence consisted of 405 nucleotides and encoded a protein of 135 amino acids. There is >85% identity with feline, bovine, ovine, canine, and human IL-5 sequences at the nucleotide and protein level. Supernatants containing equine IL-5 were also examined for biological activity. CHO supernatant containing equine recombinant (eqr) IL-5, like the human ortholog (hrIL-5), induced concentration dependent equine eosinophil adherence to autologous serum-coated plastic (9.7+/-1.5% with a 1:100 dilution of eqrIL-5 and 9.1+/-1.6% adherence with 1 nM hrIL-5; n = 4). The eqr protein also caused concentration dependent superoxide production (11.9+/-2.4 nmol (reduced cytochrome (cyt) C)/10(6) cells at a 1:50 dilution, n = 4). In contrast, hrIL-5 only caused significant superoxide production when diluted in conditioned CHO medium, an effect that was inhibited by the anti-human mAb, TRFK5 (4.4+/-0.3 versus 0.3+/-0.4 nmol/10(6) cells for 0.5 nM hrIL-5 in the presence of the isotype matched IgG1 control (10 microM) and TRFK5 (10 microM), respectively). TRFK5 also significantly inhibited hrIL-5 induced adherence at concentrations of 0.3 microg/ml and above but had no significant inhibitory effect on either superoxide or adherence caused by eqrIL-5. These results demonstrate that equine IL-5 expressed by CHO cells stimulates equine eosinophils, suggesting that this cytokine could play a role in eosinophil recruitment and activation in equine allergic disease. The anti-human and murine moAb TRFK5 does not appear to recognise the equine protein.

Association of interleukin-5 and eotaxin with acute exacerbation of asthma

BACKGROUND

Airway eosinophilia is frequently observed during acute exacerbation of asthma. Interleukin-5 (IL-5) and eotaxin are directly involved in the airway eosinophilia found in persistent asthma. Interrelation between these cytokines is expected to occur in acute exacerbation of asthma. Thus, we evaluated the relevance of interaction between eotaxin and IL-5 in the airway inflammation of acute exacerbation.

METHODS

We measured the number of inflammatory cells and the amount of eotaxin and IL-5 in sputum from 22 healthy subjects, 21 asthmatics with acute exacerbation and 16 patients with mild persistent asthma, and reassessed these values in 7 subjects with acute exacerbation after 7 days' treatment with systemic steroid (2 mg/kg/day). Sources of IL-5 and eotaxin were investigated by immunohistochemical staining of sputum cells of 4 cases from each group.

RESULTS

Both IL-5 and eotaxin levels were higher in patients with acute exacerbation of asthma than in patients with persistent asthma and normal subjects. IL-5 and eotaxin levels were significantly correlated with eosinophil percentages in mild persistent asthma. Eotaxin staining was found mainly on macrophages and occasionally on eosinophils. Steroid treatment markedly decreased eosinophil percentages and IL-5 levels within 7 days but did not alter eotaxin levels.

CONCLUSIONS

Both IL-5 and eotaxin are associated with acute exacerbation of asthma. IL-5 rather than eotaxin is effectively decreased by the inhibitory effect of steroid in acute exacerbation.

Allergic bronchial asthma: airway inflammation and hyperresponsiveness

The international consensus report on diagnosis and treatment of asthma was published in 1992 (Clin Exp Allergy 22: 1-72). According to the report, asthma is a chronic inflammatory disorder of the airways in which many cells play a role, including mast cells and eosinophils. Airway inflammation causes various symptoms of asthma which are usually associated with widespread but variable airflow obstruction and causes an associated increase in airway responsiveness to a variety of stimuli. The definition of asthma, provided in this report, is an epoch-making revision of the conventional recognition of asthma based on respiratory physiology and does not contradict the empirical knowledge that asthma responds well to steroid therapy. One reason, which led airway inflammation to be understood as a major factor in the pathophysiology of asthma is the technological advance and the widespread use of bronchoscopes. The use of bronchoscopy as a research tool has markedly improved the understanding of the pathology of asthma. It became also possible to link biopsy findings to autopsy findings in patients who died of asthma. However, it is relatively difficult to repeat a biopsy of the airway mucosal membranes in individual asthmatic patients. Here, animal models of asthma play a significant role. Findings from animal models can provide a clue for the development of new anti-asthmatic drugs. This paper will deal with the paradigm of allergic asthma and focus on recent topics of interleukin (IL)-4 and IL-5, which seem to play a central role in allergic asthma. The causative relationship between airway inflammation and hyperresponsiveness will be discussed.

Allergen-induced fluctuation in CC chemokine receptor 3 expression on bone marrow CD34+ cells from asthmatic subjects: significance for mobilization of haemopoietic progenitor cells in allergic inflammation

There is increasing evidence that primitive progenitors migrate from the bone marrow (BM) via the peripheral circulation to tissue sites where they undergo in situ differentiation to provide a continued source of effector cells, such as eosinophils, during an allergic inflammatory response. To study mechanisms of progenitor cell mobilization in allergic reactions, we investigated fluctuations in the expression of the eotaxin receptor, CC chemokine receptor 3 (CCR3), on CD34+ cells from stable asthmatics following allergen (i.e. antigen) challenge. BM aspirates were taken from seven early responder (ER) and 10 dual responder (DR) asthmatics who, following antigen challenge developed only an early bronchoconstrictor response and an early and late- bronchoconstrictor response, respectively. Expression of CCR3 was detected on primitive (CD34+ cells) and eosinophil-lineage committed progenitors (CD34+ interleukin-5 receptor alpha-subunit+ cells) by flow cytometry and confirmed by co-localization of CCR3 messenger RNA to CD34 immunopositive cells using in situ hybridization. When preantigen levels were compared to 24-hr postantigen levels, significant increases in BM CD34+ CCR3+ cells were detected in DR, who also developed a significant sputum and blood eosinophilia and increased methacholine airway responsiveness. In contrast, a significant attenuation of BM CD34+ CCR3+ cells was observed in ER. In a dose-dependent manner eotaxin, but not interleukin (IL)-5, stimulated CD34+ progenitor cell migration in vitro. This migrational response to eotaxin was abrogated by anti-CCR3 monoclonal antibody and primed by preincubation with IL-5. We propose that fluctuations in CCR3 expression on human BM CD34+ cells may facilitate chemokine-mediated progenitor cell mobilization to the peripheral circulation and the resultant development of pulmonary eosinophilia, a cardinal feature of asthma.

DNA: a programmable force sensor

Direct quantification of biomolecular interaction by single-molecule force spectroscopy has evolved into a powerful tool for materials and life sciences. We introduce an approach in which the unbinding forces required to break intermolecular bonds are measured in a differential format by comparison with a known reference bond (here, a short DNA duplex). In addition to a marked increase in sensitivity and force resolution, which enabled us to resolve single-base pair mismatches, this concept allows for highly specific parallel assays. This option was exploited to overcome cross-reactions of antibodies in a protein biochip application.

Effect of SCH55700, a humanized anti-human interleukin-5 antibody, in severe persistent asthma: a pilot study

Antagonizing the effect of interleukin (IL)-5 is a potential new treatment strategy in allergic disorders. We evaluated the safety, biological activity, and pharmacokinetics of SCH55700, a humanized anti-human IL-5 antibody, in subjects with severe persistent asthma treated with oral or high doses of inhaled steroids. In a double-blind, randomized, multicenter trial, a rising single dose of SCH55700 (0.03 mg/kg [n = 2], 0.1 mg/kg [n = 4], 0.3 mg/kg [n = 6], or 1.0 mg/kg [n = 12]) or placebo (n = 8) was administered intravenously. SCH55700 dose dependently reduced circulating eosinophil counts. At a dose of 1.0 mg/kg, the decrease remained significant up to Day 30 [(0.07 +/- 0.01) x 10(9)/L versus (0.23 +/- 0.04) x 10(9)/L at baseline] (mean +/- SEM) (p = 0.05). After administration of SCH55700 at 0.3 and 1.0 mg/kg, a trend toward improvement in baseline FEV1 was observed, which reached significance 24 hours after the 0.3-mg/kg dose (p = 0.019 versus placebo). No significant changes occurred in other clinical indices of disease activity. Adverse events were not different between active treatment and placebo. We conclude that SCH55700 is a biologically active anti-human IL-5 antibody that can be safely used in severe steroid-treated asthma. Its therapeutic potential needs to be addressed in specifically designed efficacy trials.

Development and evaluation of a flow-cytometric assay of specific cell-mediated immune response in activated whole blood for the detection of cell-mediated immunity against varicella-zoster virus

A new assay for the detection of specific cell-mediated immune (CMI) responses is described. Whole blood, diluted 1/10 in medium, was cultured in the presence or the absence of specific antigens. Results were assessed by flow cytometric analysis with or without immunophenotyping to detect proliferating lymphoblasts among cultured cells. Interferon-gamma, IL-10, and IL-5 in culture supernatants are measured by ELISAs. The assay was evaluated using samples from 37 VZV-antibody-positive children with a history of chickenpox and samples from 15 seronegative children without a history of chickenpox; it displayed a sensitivity of 95% and a specificity of 100% for the detection of varicella-zoster virus (VZV)-specific CMI. The intraassay and interassay variations of the new test were lower than with the conventional assay for CMI, detecting thymidine incorporation in peripheral blood mononuclear cells (PBMCs). Cytokines were detected in only 70% of cultures from VZV-antibody-positive subjects. The cytokine response was restricted to IFN-gamma in most cases. The Flow-cytometric Assay of Specific Cell-mediated Immune response in Activated whole blood (FASCIA) is a precise and accurate yet simple and convenient test that can be readily employed for the examination of single samples as well as for large-scale studies.

Marked airway eosinophilia prevents development of airway hyper-responsiveness during an allergic response in IL-5 transgenic mice

Tissue eosinophilia probably plays important roles in the pathophysiology of bronchial asthma and allergic disorders; however, this concept was challenged recently by controversial results in mouse models of bronchial asthma treated with anti-IL-5 Ab and the failure of anti-IL-5 therapy in humans. We have now used a unique model, IL-5 transgenic (TG) mice, to address a fundamental question: is airway eosinophilia beneficial or detrimental in the allergic response? After sensitization and challenge with OVA, IL-5 TG mice showed a marked airway eosinophilia. Surprisingly, these IL-5 TG mice showed lower airway reactivity to methacholine. Immunohistochemical analysis of the lungs revealed a marked peribronchial infiltration of eosinophils, but no eosinophil degranulation. In vitro, mouse eosinophils from peritoneal lavage fluids did not produce superoxide anion, but did produce an anti-inflammatory and fibrotic cytokine, TGF-beta 1. Indeed, the TGF-beta 1 levels in bronchoalveolar lavage fluid specimens from IL-5 TG mice directly correlated with airway eosinophilia (r = 0.755). Furthermore, anti-IL-5 treatment of IL-5 TG mice decreased both airway eosinophilia and TGF-beta 1 levels in bronchoalveolar lavage fluids and increased airway reactivity. Thus, in mice, marked eosinophilia prevents the development of airway hyper-reactivity during an allergic response. Overall, the roles of eosinophils in asthma and in animal models need to be addressed carefully for their potentially detrimental and beneficial effects.

Generation of gingival T cell lines/clones specific with Porphyromonas gingivalis pulsed dendritic cells from periodontitis patients

OBJECTIVES AND BACKGROUND

It is well documented that in periodontitis lesions, most infiltrated gingival T cells are antigen-specific memory T cells. These cells play an important role as regulators and effector cells in the pathogenesis of periodontitis. In this study, we used dendritic cells (DCs) as antigen-presenting cells to generate human gingival T cell lines and clones specific for Porphyromonas gingivalis from periodontitis patients.

METHODS

Autologous DCs were derived from the patients' adherent monocytes using granulocyte-macrophage colony-stimulating factor and interleukin (IL)-4. Lymphocytes were isolated from gingival biopsies using collagenase enzyme digestion and the number was increased by subsequent culturing in IL-2-containing medium. T cells were then negatively sorted using flow cytometry, cocultured with P. gingivalis-pulsed DCs and subsequently expanded in the culture medium containing IL-2. T cells were kept viable and active by periodic exposure to antigen-pulsed DCs. The specificity of the T cell lines was tested against four plaque bacteria: P. gingivalis, Actinobacillus actinomycetemcomitans, Prevotella intermedia and Actinomyces viscosus. The established T cell lines were then cloned. Three P. gingivalis-specific T cell lines and 12 gingival T cell clones were generated. They all showed good specificity against P. gingivalis but not to other plaque bacteria.

RESULTS

All T cell clones were positive for CD4 and the majority of them produced interferon gamma, but a minimal or negligible amount of IL-5.

CONCLUSIONS

The data obtained clearly showed that monocyte-derived DCs could be used as powerful antigen-presenting cells to generate antigen-specific T cells from periodontitis tissues.

Technology evaluation: mepolizumab, GlaxoSmithKline

GlaxoSmithKline (formerly SmithKline Beecham) is developing mepolizumab (SB-240563), a monoclonal antibody directed against IL-5, as a potential treatment for asthma and atopic dermatitis. Phase II trials in asthma were underway by April 1998 and by March 2002, phase II trials had also been initiated in atopic dermatitis.

Neuropeptide-induced inhibition of IL-16 release from eosinophils

OBJECTIVES

Eosinophils are prominent inflammatory cells that respond to peripheral neuropeptides in vitro and in vivo. At inflammatory sites, cytokines activate distinct cellular and biochemical pathways that act in a coordinated fashion. We investigated whether peripheral neuropeptides can act as immunomodulators by influencing cytokine release from eosinophils.

METHODS

Human eosinophils were enriched using magnetic cell sorting, and IL-16 levels in supernatants from maintained eosinophils were measured by ELISA. Biological activity of IL-16 was confirmed in lymphocyte chemotaxis assays.

RESULTS

Substance P, vasoactive intestinal polypeptide, calcitonin gene-related peptide and secretoneurin reduced the IL-16 release from eosinophils; this effect was additive to that observed with GM-CSF or IL-5. Decreased IL-16 levels in supernatants resulted in reduced lymphocyte chemotaxis, whereas supernatants derived from SP-treated eosinophils stimulated lymphocyte chemotaxis, even though IL-16 was decreased.

CONCLUSIONS

Results suggest that distinct neuropeptides are able to reduce the number of lymphocytes at inflammatory sites during existing eosinophilia by inhibiting eosinophil IL-16 release, thus attenuating the pro-inflammatory action of lymphocytes and monocytes.