Expression of IL-16 in allergen-induced late-phase nasal responses and relation to topical glucocorticosteroid treatment

Allergen-induced late nasal responses (LNRs) are associated with a cellular infiltrate in which CD4+ cells are prominent. These cells have been shown to be the major cellular source of Th2-type cytokines. Mechanisms responsible for the local accumulation of CD4+ cells in the nasal mucosa after allergen exposure are unclear. IL-16 is a potent chemoattractant for CD4+ cells in vitro and may play a significant role in recruiting CD4+ cells in LNRs. We investigated the expression of IL-16 messenger RNA and immunoreactivity in nasal biopsy specimens from 17 subjects with allergic rhinitis. A biopsy specimen of the nasal inferior turbinate was obtained before and 24 hours after local nasal provocation with grass pollen extract after 6 weeks of treatment with either topical fluticasone propionate (n = 9) or placebo (n = 8) nasal spray twice daily. IL-16 mRNA-positive cells and IL-16-immunoreactive cells were identified in both the epithelium and the subepithelial tissue at baseline. Within the placebo-treated group, the numbers of epithelial and subepithelial IL-16 mRNA-positive cells and IL-16-immunoreactive cells were significantly increased 24 hours after challenge compared with baseline (p < 0.001). Topical glucocorticoid therapy resulted in a decrease in allergen-induced epithelial immunoreactive cells and subepithelial IL-16 mRNA-positive cells. The numbers of CD4+ cells increased after antigen challenge compared with baseline (p < 0.05), and this increase was inhibited by glucocorticoid treatment. There were significant correlations between epithelial and subepithelial IL-16 immunoreactivity and CD4+ cell infiltration after antigen challenge. The upregulation of IL-16 expression in allergic nasal mucosa after antigen challenge may have critical implications in the accumulation of CD4+ cells in response to antigen exposure. Steroid-mediated inhibition of IL-16 may be partly responsible for the decrease in local CD4+ cells after topical glucocorticoid therapy.

IL-5 production by allergen-stimulated T cells following grass pollen immunotherapy for seasonal allergic rhinitis

Grass pollen immunotherapy for the treatment of seasonal allergic rhinitis ('summer hayfever') results in improvement in symptoms, a reduction in the early and late phase responses to allergen provocation and decreased tissue eosinophilia. Immunotherapy may act by altering the pattern of cytokine production by allergen-specific T cells from a 'Th2-type' (IL-4 and IL-5) profile to a 'Th1-type' (interferon-gamma (IFN-gamma)) profile. We set out to determine whether clinical improvement following specific allergen immunotherapy is accompanied by reduced production of the pro-eosinophilic and archetypal 'Th2-type' cytokine, IL-5. Peripheral blood mononuclear cells (PBMC) were isolated from (i) 13 patients who had received 6 or 7 years' continuous conventional immunotherapy with timothy grass pollen (Phleum pratense); (ii) 14 patients who had received 3 or 4 years of conventional immunotherapy followed by 3 years of placebo treatment; (iii) 12 matched seasonal rhinitic patients who had never received immunotherapy; and (iv) 17 non-atopic normal controls. PBMC were stimulated with 20 microg/ml and 200 microg/ml P. pratense extract, or 10 microg/ml of Mycobacterium tuberculosis purified protein derivative (PPD), at 2 x 10(6) cells/ml and 5 x 10(6) cells/ml. IL-5 concentrations in culture supernatants collected after 6 days' culture were measured by ELISA. IL-5 production in response to stimulation with P. pratense extract was highly reproducible and was elevated in both of the immunotherapy treated groups and the untreated rhinitics relative to non-atopic controls (P<0.005 for each group relative to non-atopic controls, under each of the four conditions tested). However, no significant reduction was observed in IL-5 production when immunotherapy treated patients were compared with untreated rhinitic controls. Moreover, abrogation of the cutaneous late-phase responses to allergen following treatment was not associated with reduced IL-5 production by allergen-stimulated peripheral blood T cells. Reduced IL-5 production by peripheral blood T cells may not be necessary for immunotherapy to be effective. Local immunodulation of T cell responses may play a role in this form of treatment.

Relationship between IL-4 and IL-5 mRNA expression and disease severity in atopic asthma

Atopic asthma is characterized by chronic inflammation of the bronchial mucosa in which eosinophil- and immunoglobulin E (IgE)-dependent mechanisms are believed to be prominent. Therefore, specific proeosinophilic mediators such as interleukin (IL)-5 and essential cofactors for IgE switching in B-lymphocytes such as IL-4 could play a pivotal role in asthma. However, the exact role that individual inflammatory mediators play in the development of the disease in humans is still unknown. Using semiquantitative reverse transcriptase-polymerase chain reaction amplification in bronchial biopsies from 10 atopic asthmatics, we have tested the hypothesis that IL-4 and IL-5 mRNA expression relative to beta-actin mRNA correlates with validated indicators of disease severity. IL-4 and IL-5 mRNA copies relative to beta-actin mRNA were detected in bronchial biopsies from atopic asthmatics. The numbers of IL-5 mRNA copies relative to beta-actin mRNA correlated with disease severity assessed by the Aas asthma score (r = 0.70, p = 0.01), baseline FEV1 (r = -0.94, p = 0.001), baseline peak expiratory flow rate (r = -0.77, p = 0.01), peak expiratory flow rate variability over 2 wk (r = 0.69, p = 0.028), and the histamine PC20 (r = -0.72, p = 0.018). Conversely, the numbers of IL-4 mRNA copies relative to beta-actin mRNA did not correlate with asthma severity, but they positively correlated with total serum IgE concentrations (r = -0.90, p = 0.001). Our present results support the concept that IL-5 may determine asthma clinical expression and severity, and by inference they support the development of IL-5 targeted therapies.

Skin prick testing in general practice: a pilot study

Allergy skin prick testing is regarded as a routine diagnostic procedure in hospital settings, but its role in general practice is not yet defined. Our aim was to explore the ways in which skin prick testing might facilitate the work of general practice nurses engaged in asthma patient care. A structured questionnaire was completed by 18 practice nurses before and again after administering allergy skin tests to four common aeroallergens (dust mite, grass pollen, cat and dog danders) to 319 consecutive attenders with known or suspected asthma. Nurses' decisions about whether or not to give allergen avoidance advice were reversed after skin testing in 63 (22%) cases for dust mite, 67 (23%) cases for grass pollen, 38 (13%) cases for cat fur and 49 (17%) cases for dog hair. Had allergen avoidance interventions been targeted only at patients with both a positive skin test and a positive clinical history, the number of planned interventions would have declined from 305 before skin testing to 142 after. The findings suggest that allergy skin prick testing was feasible and acceptable in general practice, and that one role may be to reduce the number of allergen avoidance interventions offered to patients unlikely to benefit.

Enhanced expression of high-affinity IgE receptor (Fc epsilon RI) alpha chain in human allergen-induced rhinitis with co-localization to mast cells, macrophages, eosinophils, and dendritic cells

BACKGROUND

IgE-dependent activation of mast cells and basophils through the high-affinity IgE receptor (Fc epsilon RI) is involved in the pathogenesis of allergen-induced immediate and late responses.

OBJECTIVE

We investigated the expression and cellular distribution of Fc epsilon RI in the nasal mucosa after allergen challenge in patients with summer hay fever.

METHODS

Fourteen grass pollen-sensitive patients and seven normal control subjects underwent nasal challenge with grass pollen and allergen diluent in random order separated by 2 weeks. Nasal airway caliber was monitored by acoustic rhinometry, and nasal biopsy was performed at 6 hours. Messenger RNA for Fc epsilon RI was determined by using reverse-transcription polymerase chain reaction, and Fc epsilon RI protein expression was determined by immunohistology with a mouse monoclonal antibody (22E7) and a rabbit polyclonal antibody (997) directed against the alpha subunit. Co-localization of Fc epsilon RI receptors was performed by using double-immunostaining methods.

RESULTS

In atopic subjects, there was a significant early decrease in nasal airway caliber, which extended up to 6 hours after allergen challenge. Fc epsilon RI mRNA levels were elevated at 6 hours (p = 0.03). Cells expressing Fc epsilon RI protein were increased in patients with atopic rhinitis compared with normal control subjects (p = 0.03). Further increases in Fc epsilon RI+ cells were observed after allergen challenge only in the atopic group (p = 0.02). Double immunohistochemistry revealed that the majority of Fc epsilon RI+ cells were mast cells (64%), followed by macrophages (20%), eosinophils (4%), and dendritic cells (2%), with 10% Fc epsilon RI+ cells being unidentified.

CONCLUSIONS

Our results demonstrate increased Fc epsilon RI expression during allergen-induced rhinitis and highlight a potential target for treatment.

IL-13 mRNA and immunoreactivity in allergen-induced rhinitis: comparison with IL-4 expression and modulation by topical glucocorticoid therapy

The allergen-induced late nasal response (LNR) is associated with high expression of interleukin-4 (IL-4) and IL-5 messenger RNA (mRNA) in the nasal mucosa, suggesting a role for Th2-type cytokines in the development of the LNR. Moreover, topical corticosteroid-mediated inhibition of the LNR is accompanied by inhibition of IL-4, but not IL-5, mRNA expression, IL-13 shares a number of functions with IL-4, including IgE switching and vascular cell adhesion molecule-1 (VCAM-1) upregulation. We investigated the expression of IL-13 mRNA and immunoreactivity in nasal biopsies from 10 normal subjects and 20 subjects with allergic rhinitis. IL-4 mRNA expression was examined in the same subjects. The allergic rhinitis patients were randomized to receive a 6-wk treatment with either topical fluticasone propionate (n = 10) or placebo (n = 10) nasal spray twice daily. A nasal biopsy was taken before treatment and 24 h after local nasal allergen provocation with a grass-pollen extract. Before treatment, there was no significant difference between the allergic rhinitis patients and controls in the expression of IL-13 mRNA and immunoreactivity. After allergen provocation, we observed a significant increase in IL-13 mRNA-positive and immunoreactive cells at 24 h only in subjects given placebo (P < 0.001). Inhibition of the LNR after corticosteroid treatment was associated with a marked decrease in allergen-induced IL-13 mRNA-positive (P < 0.001) and immunoreactive cells (P < 0.001). In subjects given placebo, 76.9 +/- 5.5% of IL-13 mRNA-positive cells observed after allergen were CD3+, whereas 11.2 +/- 2.7% coexpressed immunoreactivity for mast-cell tryptase. In these subjects, increases in cells expressing IL-13 mRNA were greater than for IL-4 mRNA (P = 0.001), and double in situ hybridization studies revealed that 100% of the IL-4 mRNA-positive cells coexpressed IL-13 mRNA, whereas 66.6 +/- 10.5% of IL-13 mRNA-positive cells coexpressed IL-4 transcripts after allergen challenge. The results of this study suggest that IL-13 expression is a prominent feature of the LNR, and that inhibition of the LNR following steroid therapy may be partly attributable to inhibition of IL-13 expression.

Associations between IL-13 and IL-4 (mRNA and protein), vascular cell adhesion molecule-1 expression, and the infiltration of eosinophils, macrophages, and T cells in allergen-induced late-phase cutaneous reactions in atopic subjects

IL-13, like IL-4, induces up-regulation of vascular cell adhesion molecule-1 (VCAM-1) expression on human endothelial cells in vitro. This may contribute to local accumulation of alpha4beta1+ inflammatory cells, such as eosinophils, macrophages, and T cells. We tested the hypothesis that in human allergic inflammatory reactions in vivo, IL-13 and IL-4 are both involved in VCAM-1/alpha4beta1-dependent recruitment of inflammatory cells. Cryostat cutaneous sections from 13 atopic subjects taken 6, 24, and 48 h after allergen challenge were processed for immunohistochemical staining and in situ hybridization using mAbs and 35S-labeled riboprobes for IL-4 and IL-13. When compared with diluent sites, allergen provoked significant increases in the numbers of cells that were mRNA+ and protein-positive for both IL-13 and IL-4 that were clearly demonstrable at 6 h, peaked at 24 h, and declined by 48 h. Double immunohistochemical staining/in situ hybridization showed that the majority (&gt;60%) of IL-13 mRNA+ signals were colocalized to CD3+ T cells. The numbers of mRNA+ and protein-positive cells for IL-13 significantly correlated with VCAM-1 immunoreactivity on endothelial cells and with total numbers of infiltrating EG2+ eosinophils, CD45RO+ T cells, and CD68+ macrophages, but not elastase-positive neutrophils, at the 6- and 24-h time points. At 6 h, an association was also observed between the numbers of IL-4 mRNA+ or protein product-positive cells and VCAM-1 expression, although this was not statistically significant. These findings suggest that IL-13 may play an important role in recruitment of inflammatory cells to the site of cutaneous allergic inflammatory reaction through VCAM-1/alpha4beta1-dependent mechanisms.

Associations between IL-13 and IL-4 (mRNA and protein), vascular cell adhesion molecule-1 expression, and the infiltration of eosinophils, macrophages, and T cells in allergen-induced late-phase cutaneous reactions in atopic subjects

IL-13, like IL-4, induces up-regulation of vascular cell adhesion molecule-1 (VCAM-1) expression on human endothelial cells in vitro. This may contribute to local accumulation of alpha4beta1+ inflammatory cells, such as eosinophils, macrophages, and T cells. We tested the hypothesis that in human allergic inflammatory reactions in vivo, IL-13 and IL-4 are both involved in VCAM-1/alpha4beta1-dependent recruitment of inflammatory cells. Cryostat cutaneous sections from 13 atopic subjects taken 6, 24, and 48 h after allergen challenge were processed for immunohistochemical staining and in situ hybridization using mAbs and 35S-labeled riboprobes for IL-4 and IL-13. When compared with diluent sites, allergen provoked significant increases in the numbers of cells that were mRNA+ and protein-positive for both IL-13 and IL-4 that were clearly demonstrable at 6 h, peaked at 24 h, and declined by 48 h. Double immunohistochemical staining/in situ hybridization showed that the majority (>60%) of IL-13 mRNA+ signals were colocalized to CD3+ T cells. The numbers of mRNA+ and protein-positive cells for IL-13 significantly correlated with VCAM-1 immunoreactivity on endothelial cells and with total numbers of infiltrating EG2+ eosinophils, CD45RO+ T cells, and CD68+ macrophages, but not elastase-positive neutrophils, at the 6- and 24-h time points. At 6 h, an association was also observed between the numbers of IL-4 mRNA+ or protein product-positive cells and VCAM-1 expression, although this was not statistically significant. These findings suggest that IL-13 may play an important role in recruitment of inflammatory cells to the site of cutaneous allergic inflammatory reaction through VCAM-1/alpha4beta1-dependent mechanisms.

Local IgE production in nasal allergy

IgE mediates allergic reactions by binding to the high-affinity receptor, Fc epsilonR1, on mast cells and basophils at mucosal surfaces; then cross-linking of the receptor by multivalent antigen triggers the allergic response. We demonstrate here that B cells in the nasal mucosa of patients with hay fever express IgE. The results also suggest that allergen-induced heavy-chain switching to IgE occurs locally within the nasal mucosa. Local IgE synthesis may explain why some 'atopic' patients develop rhinitis whereas others have either no clinical manifestations or develop atopic disease elsewhere.

Dermatobia hominis in the accident and emergency department: "I've got you under my skin"

An unusual form of larval infestation from South America is presented which, in view of increasing tourism to South america's tropical areas, may present to any accident and emergency department. Infestation with Dermatobia hominis is reviewed in terms of clinical recognition and life cycle. Techniques of removal are described.

IL-13 production by allergen-stimulated T cells is increased in allergic disease and associated with IL-5 but not IFN-gamma expression

Interleukin-13 (IL-13) shares many, but not all, of the properties of the prototypic T-helper type 2 (Th2) cytokine IL-4, but its role in allergen-driven T-cell responses remains poorly defined. We hypothesized that allergen stimulation of peripheral blood T cells from patients with atopic disease compared with non-atopic controls results in elevated IL-13 synthesis in the context of a 'Th2-type' pattern. Freshly isolated peripheral blood mononuclear cells (PBMC) obtained from sensitized atopic patients with allergic disease, and non-atopic control subjects, were cultured with the allergens Phleum pratense (Timothy grass pollen) or Dermatophagoides pteronyssinus (house dust mite) and the non-allergenic recall antigen Mycobacterium tuberculosis purified protein derivative (PPD). Supernatant concentrations of IL-13, along with IL-5 and interferon-gamma (IFN-gamma) (Th2- and Th1-type cytokines, respectively) were determined by enzyme-linked immunosorbent assay (ELISA). Allergen-induced IL-13 and IL-5 production by T cells from patients with allergic disease was markedly elevated (P = 0.0075 and P = 0.0004, respectively) compared with non-atopic controls, whereas IFN-gamma production was not significantly different. In contrast to allergen, the prototypic Th1-type antigen M. tuberculosis PPD induced an excess of IFN-gamma over IL-13 and IL-5 production, and absolute concentrations of cytokines were not affected by the presence or absence of atopic disease. Addition of exogenous recombinant IFN-gamma or IL-12, cytokines known to inhibit Th2-type responses, significantly inhibited allergen-driven production of both IL-13 and IL-5, but not T-cell proliferation, whereas exogenous IL-4 did not significantly affect production of IL-13 or IL-5. We conclude that allergen-specific T cells from atopic subjects secrete elevated quantities of IL-13 compared with non-atopic controls, in the context of a Th2-type pattern of cytokine production.

Upregulation of alpha GM-CSF-receptor in nonatopic asthma but not in atopic asthma

BACKGROUND

Intrinsic asthma is characterized by an increased number of activated eosinophils and macrophages and an increased expression of the hematopoietic growth factor granulocyte-macrophage colony-stimulating factor (GM-CSF) in the bronchial mucosa.

OBJECTIVE

This study was carried out to investigate the expression of alpha GM-CSF receptor (alpha GM-CSFr) messenger RNA and protein in the bronchial mucosa of patients with intrinsic or atopic asthma and of control subjects and to correlate the expression of alpha GM-CSFr to the number of EG2+ cells (eosinophils) and CD68+ cells (macrophages) and pulmonary function.

METHODS

Nineteen patients with stable asthma (9 with atopic and 10 with intrinsic asthma) and 22 normal control subjects (12 atopic and 10 nonatopic subjects) were recruited, and FEV1 (percent predicted) and PC20 were measured before bronchoscopy. Endobronchial biopsy specimens were obtained and examined for membrane-bound alpha GM-CSFr by using in situ hybridization and immunocytochemistry.

RESULTS

alpha GM-CSFr mRNA- and protein-positive cells were identified in biopsy specimens from all four groups studied. There was no significant difference in the number of cells expressing alpha GM-CSFr mRNA and protein in patients with atopic asthma compared with atopic and nonatopic control subjects. However, the numbers of alpha GM-CSFr mRNA- and protein-positive cells were significantly higher in nonatopic patients with asthma compared with atopic patients with asthma and atopic and nonatopic control subjects (p < 0.001). In the patients with intrinsic asthma, the number of alpha GM-CSFr mRNA-positive cells per millimeter of basement membrane correlated with numbers of CD68+ cells (r2 = 0.87, p < 0.001) but not with EG2+ cells, and colocalization studies demonstrated that 80% of the cells expressing alpha GMCSFr mRNA were CD68+. The expression of GM-CSF was also significantly increased in patients with intrinsic asthma compared with those with atopic asthma and control subjects (p < 0.05). In addition, in intrinsic asthma, there was a correlation between alpha GM-CSFr mRNA and FEV1 (r2 = 0.61, p < 0.05).

CONCLUSION

These results demonstrate that elevated numbers of cells expressing alpha GM-CSFr can be detected in nonatopic asthma but not in atopic asthma and suggest that this increased expression is predominantly macrophage-associated and may play an important pathophysiologic role in intrinsic asthma.

Elevated expression of messenger ribonucleic acid encoding IL-13 in the bronchial mucosa of atopic and nonatopic subjects with asthma

Local secretion of cytokines by T cells within the bronchial mucosa, with consequent selective eosinophil influx, has been implicated in the pathogenesis of bronchial asthma. The cytokine IL-13 exhibits activities (selective eosinophil vascular adhesion by very late antigen-4/vascular cell adhesion molecule-1 interaction and promotion of IgE synthesis and "T112-type" T cell responses) that may be relevant to this process. We hypothesized that, compared with conditions in control subjects, elevated expression of messenger ribonucleic acid (mRNA) encoding IL-13 is a feature of the bronchial mucosa of both atopic (positive skin prick test result to at least one of a range of common aeroallergens) and nonatopic (negative skin prick test results and serum total IgE concentrations within the normal range) subjects with asthma. With use of a semiquantitative reverse transcriptase-polymerase chain reaction technique, we measured the quantities (relative to beta-actin) of IL-13 mRNA in bronchial mucosal biopsy specimens from atopic and nonatopic subjects with asthma and atopic and nonatopic control subjects. Biopsy specimens from the subjects with asthma, whether the subjects were atopic or nonatopic, had statistically equivalent quantities of IL-13 mRNA relative to beta-actin, and these quantities were significantly elevated compared with those in specimens from both the atopic and nonatopic control subjects (p < or = 0.02 in each case), in which the quantities of IL-13 mRNA relative to beta-actin were also statistically equivalent. The quantities of IL-13 mRNA reflected the numbers of EG2+ eosinophils per unit area of submucosa in the biopsy specimens as determined by immunohistochemistry, which were statistically equivalent in the atopic and nonatopic subjects with asthma and significantly elevated as compared with those in both the atopic and nonatopic control subjects without asthma (p < or = 0.007 in each case). Taking the subjects with asthma as a group, no correlations were observed between the quantities of IL-13 mRNA (relative to beta-actin) and several measures of disease severity. These data are consistent with the hypothesis that IL-13 plays a role in the pathogenesis of both atopic and nonatopic asthma, at least partly through promoting recruitment of eosinophils to the bronchial mucosa, although other factors may be more important in regulating the severity of the disease.

Effect of cyclosporin A on the allergen-induced late asthmatic reaction

BACKGROUND

The allergen-induced late asthmatic reaction (LAR) is associated with mucosal inflammation involving several cell types including activated T lymphocytes and eosinophils. In contrast, the early asthmatic reaction (EAR) is considered to results from rapid allergen-induced release of bronchoconstrictor mediators from IgE sensitised mast cells. Cyclosporin A has efficacy in chronic severe corticosteroid-dependent asthma and is believed to act principally by inhibiting cytokine mRNA transcription in T lymphocytes. However, it has effects on other cell types in vitro, including the inhibition of exocytosis/degranulation events in mast cells. It was therefore hypothesised that cyclosporin A would attenuate both the EAR and LAR in subjects with mild asthma.

METHODS

Twelve sensitised atopic asthmatic subjects with documented dual asthmatic responses were studied in a double blind, placebo controlled, crossover trial. On two separate study visits subjects received two oral doses of either cyclosporin A or matched placebo before inhaled allergen challenges. The forced expiratory volume in one second (FEV1) was measured half hourly for eight hours and blood eosinophil counts were analysed three, six, and 24 hours after the challenge. Treatment effects on blood eosinophil counts as well as the EAR and LAR, respectively defined as the areas under the curve (AUC) of FEV1 changes from baseline between 0-1 and 4-8 hours after challenge, were compared by non-parametric crossover analysis.

RESULTS

Cyclosporin A reduced both the LAR (median AUC -41.9 1.h (interquartile range -82.7 to -12.4) for cyclosporin A and -84.5 1.h (-248.9 to -39.1) for placebo; p = 0.007) and the late increase in blood eosinophils (median 0.2 x 10(9)/1 (0.15 to 0.4) for cyclosporin A and 0.4 x 10(9)/1 (0.25 to 0.55) for placebo; p = 0.024) but had no effect on the EAR. The reduction of the LAR by cyclosporin A correlated significantly with prechallenge blood concentrations of cyclosporin A (r = 0.6, p = 0.028).

CONCLUSIONS

These data are consistent with the concept that cyclosporin A has anti-inflammatory actions in asthma resulting from inhibition of mRNA transcription of eosinophil-active cytokines, predominantly in T lymphocytes. Cyclosporin A, possibly in its inhaled form, or other agents which prevent cytokine gene transcription may therefore have potential in ameliorating the inflammatory component of asthma.

Allergen-induced recruitment of Fc epsilon RI+ eosinophils in human atopic skin

We have attempted to identify Fc epsilon RI+ eosinophils in cutaneous late-phase reaction in atopic subjects biopsied at 6, 24 and 48 h after the injection of either allergen or a diluent control. Compared to the diluent sites, allergen-injected sites had significantly increased numbers of eosinophils, peaking between 6 and 24 h, of which approximately 20-30% expressed mRNA for the alpha, beta, and gamma chains of Fc epsilon RI, as shown by in situ hybridization. Using either a monoclonal or a polyclonal anti-alpha chain antibody, the Fc epsilon RI alpha protein also co-localized to approximately 50-80% of eosinophils at all time points studied. We also observed a significant correlation (r = 0.89; p = 0.02) between the numbers of Fc epsilon RI+ (997+)/EG2+ eosinophils and the magnitude of the late-phase reaction. Thus, a significant proportion of eosinophils infiltrating the site of allergen-induced allergic tissue reactions in atopic subjects express Fc epsilon. RI. The findings show that high-affinity IgE receptors may play a role in eosinophil secretory processes in vivo.

Eosinophils and eosinophil-associated cytokines in allergic inflammation

Eosinophils are major effector cells in allergic tissue reactions. Their capacity to synthesize and store cytokines, particularly Th2-type cytokines, which may have autocrine effects such as increased cell survival in tissues, is of particular current interest. We have shown that eosinophils infiltrating the site of human cutaneous late-phase reactions (LPR) express mRNA and protein product for IL-4 and IL-5. Stimulation of peripheral blood eosinophils in vitro with either IgG or sIgA produces time-dependent induction of IL-4 and IL-5 transcription, indicating that mature cells may undergo local cytokine synthesis. We also demonstrated that bronchial biopsies from patients with both atopic and non-atopic (intrinsic) asthma express IL-4 and IL-5 mRNA which mainly co-localized to T cells, although clear hybridization signals were also obtained with eosinophils and mast cells. On the other hand, immunoreactivity for the corresponding protein was detectable predominantly in eosinophils and mast cells; a finding believed to reflect granule storage of cytokines. We also studied the resolution of the cutaneous LPR. Apoptosis of eosinophils persisted slightly longer than neutrophils in the tissues. The eventual decline in both neutrophil and eosinophil numbers followed on from the peak of the LPR. This was associated with terminal-deoxynucteotidyl-transferase-mediated nick and labelling positive (TUNEL+) (apoptotic) cells with the subsequent removal of apoptotic neutrophils and eosinophils by tissue macrophages. Thus, IL-4 and IL-5 production by eosinophils may amplify local allergic inflammatory responses and, in the case of IL-5, may prolong local tissue survival. However, in the allergen-induced LPR, inflammation rapidly resolves, possibly through the initiation of programmed cell death and phagocytosis of apoptotic cells by macrophages.

IL-5 secretion by allergen-stimulated CD4+ T cells in primary culture: relationship to expression of allergic disease

BACKGROUND

IL-5-producing allergen-specific T cells are thought to play a prominent role in the pathogenesis of allergic inflammation. We hypothesized that T cell allergen-driven IL-5 synthesis is elevated in patients with atopic disease as compared with that in atopic patients free of disease and nonatopic control subjects.

OBJECTIVES

The purpose of this study was to compare IL-5 and interferon-gamma (IFN-gamma) secretion and proliferation by peripheral blood T cells from sensitized atopic patients with asthma, rhinitis, and no symptoms and from nonatopic control subjects in response to the allergen Dermatophagoides pteronyssinus (Der p) and the control recall antigen Mycobacterium tuberculosis purified protein derivative (PPD).

METHODS

To measure allergen-induced IL-5 production and proliferation, we developed a short-term culture technique that required a single antigenic stimulation of freshly isolated peripheral blood mononuclear cells (PBMC). With this technique, we measured Der p- and PPD-induced IL-5 production and proliferation in PBMC from atopic patients with asthma who were allergic to Der p, atopic patients with rhinitis, atopic patients with no symptoms, and a group of nonatopic normal control subjects. In four experiments, CD4+ or CD8+ T cells were depleted from PBMC to confirm that IL-5 synthesis was T cell dependent.

RESULTS

T cell IL-5 production, but not IFN-gamma production, in response to Der p was elevated in atopic patients with asthma and atopic patients with rhinitis compared with findings in atopic patients with no symptoms or nonatopic control subjects. IL-5 production was abrogated by depletion of CD4+, but not CD8+, T cells. In subjects with asthma, allergen-driven IL-5 production correlated with bronchial hyperreactivity. Allergen-induced proliferation was also higher in patients with asthma than in atopic subjects with no symptoms or nonatopic controls. T cell IL-5 and IFN-gamma production and proliferation in response to PPD were similar regardless of atopic status or disease.

CONCLUSIONS

Elevated IL-5 production is a characteristic of allergen-specific peripheral blood CD4+ T cells from sensitized patients with atopic disease but not atopy per se.

Membrane-bound and soluble alpha IL-5 receptor mRNA in the bronchial mucosa of atopic and nonatopic asthmatics

Eosinophilic inflammation and interleukin-5 (IL-5) expression are characteristic features of the bronchial mucosa in asthma. We have investigated the differential expression of membrane and soluble isoforms of alpha IL-5 receptor (alpha IL-5Rm and alpha IL-5Rs) mRNA in asthmatics and in normal control subjects and examined the correlation between alpha IL-5Rm and alpha IL-5Rs expression and the FEV1 and airway hyperresponsiveness. Nineteen subjects with stable asthma (atopic = 9; intrinsic = 10) and 22 control subjects (atopic = 12; nonatopic = 10) were recruited. Endobronchial biopsies were obtained and processed for in situ hybridization and double-staining techniques. There was a significant increase in the number of cells per millimeter basement membrane expressing mRNA for total, membrane-bound, and soluble alpha IL-5R in asthmatics when compared with that in nonasthmatic control subjects (p < 0.001); 93% of the cells positive for alpha IL-5R mRNA were EG2+ve eosinophils. There was no significant difference in the expression of alpha IL-5Rm and alpha IL-5Rs between the atopic and nonatopic asthmatics. The expression of alpha IL-5Rm and alpha IL-5Rs was also nonsignificantly different between the atopic and nonatopic control subjects. However, in the asthmatic subjects, the number of positive cells expressing mRNA for alpha IL-5Rm inversely correlated with FEV1(r2 = 0.89, p < 0.001), whereas the expression of alpha IL-5Rs mRNA directly correlated with FEV1 (r2 = 0.52, p < 0.001). There were no significant correlations between alpha IL-5R isoforms and the methacholine PC20. These results suggest that alpha IL-5R upregulation and differential regulation of alternatively spliced alpha IL-5R mRNA transcripts may influence the eosinophil response and the accompanying changes in airflow limitation in both atopic and nonatopic variants of chronic asthma.

Expression of IL-4 and IL-5 mRNA and protein product by CD4+ and CD8+ T cells, eosinophils, and mast cells in bronchial biopsies obtained from atopic and nonatopic (intrinsic) asthmatics

We recently demonstrated bronchial mucosal expression of IL-4 and IL-5 at the mRNA and protein level in both atopic and nonatopic (intrinsic) asthma. In this report, using double immunohistochemistry (IHC) and in situ hybridization (ISH), we show that 70% of IL-4 and IL-5 mRNA+ signals co-localized to CD3+ T cells, the majority (&gt;70%) of which were CD4+, although CD8+ cells also expressed IL-4 and IL-5 mRNA. The remaining IL-4 and IL-5 mRNA signals co-localized to mast cells and eosinophils. The cellular distribution of these mRNA species did not differ between atopic and nonatopic asthmatics. In contrast, double IHC showed that IL-4 and IL-5 immunoreactivity was predominantly associated with eosinophils and mast cells, with few IL-5 or IL-4 immunoreactive CD3+ T cells detectable. However, total IL-4- or IL-5-positive cells detected by IHC were &lt;40% of the total mRNA+ cells, raising the possibility that insufficient cytokine protein accumulated within T cells to enable detection by IHC. We conclude that: 1) in atopic and nonatopic asthma CD8+ T cells, in addition to CD4+ T cells, mast cells and eosinophils express mRNA for IL-4 and IL-5; 2) whereas IL-4 and IL-5 mRNA expression was associated mainly with T cells, immunoreactivity for the corresponding protein products was detectable predominantly in eosinophils and mast cells; and 3) this discrepancy may be partly attributable to the relative insensitivity of double IHC technique that does not allow detection of cytokine protein in T cells where, unlike eosinophils and mast cells, there is no facility for storage and concentration in granules.

Expression of IL-4 and IL-5 mRNA and protein product by CD4+ and CD8+ T cells, eosinophils, and mast cells in bronchial biopsies obtained from atopic and nonatopic (intrinsic) asthmatics

We recently demonstrated bronchial mucosal expression of IL-4 and IL-5 at the mRNA and protein level in both atopic and nonatopic (intrinsic) asthma. In this report, using double immunohistochemistry (IHC) and in situ hybridization (ISH), we show that 70% of IL-4 and IL-5 mRNA+ signals co-localized to CD3+ T cells, the majority (>70%) of which were CD4+, although CD8+ cells also expressed IL-4 and IL-5 mRNA. The remaining IL-4 and IL-5 mRNA signals co-localized to mast cells and eosinophils. The cellular distribution of these mRNA species did not differ between atopic and nonatopic asthmatics. In contrast, double IHC showed that IL-4 and IL-5 immunoreactivity was predominantly associated with eosinophils and mast cells, with few IL-5 or IL-4 immunoreactive CD3+ T cells detectable. However, total IL-4- or IL-5-positive cells detected by IHC were <40% of the total mRNA+ cells, raising the possibility that insufficient cytokine protein accumulated within T cells to enable detection by IHC. We conclude that: 1) in atopic and nonatopic asthma CD8+ T cells, in addition to CD4+ T cells, mast cells and eosinophils express mRNA for IL-4 and IL-5; 2) whereas IL-4 and IL-5 mRNA expression was associated mainly with T cells, immunoreactivity for the corresponding protein products was detectable predominantly in eosinophils and mast cells; and 3) this discrepancy may be partly attributable to the relative insensitivity of double IHC technique that does not allow detection of cytokine protein in T cells where, unlike eosinophils and mast cells, there is no facility for storage and concentration in granules.

Localization and up-regulation of mucin (MUC2) gene expression in human nasal biopsies of patients with cystic fibrosis

Using digoxigenin-UTP-labelled human HAM-1 (92 bp) or SMUC41 (850 bp) cRNA probes, the expression and localization of MUC2 gene transcripts were determined by in situ hybridization in human nasal tissues obtained as biopsies from 12 patients with cystic fibrosis (CF): all had been part of a gene therapy trial in which CFTR cDNA-liposome complexes had been delivered by topical application to eight and liposome alone to four as a placebo control. For comparison, there were nasal tissues taken at surgical resection from four non-CF subjects and a further four biopsies taken from normal healthy volunteer controls. Both SMUC41 and HAM-1 probes provided a strong signal. MUC2 mRNA transcripts were present in serous and mucous acini of submucosal glands, ciliated and basal cells of the surface epithelium, and occasional mononuclear inflammatory cells. The percentages (mean +/- SEM) of serous and mucous acini showing positivity for MUC2 gene expression in the four samples surgically resected from non-CF subjects were 25.4 +/- 5.6 and 26.7 +/- 3.3 per cent, respectively. Compared with the non-CF subjects, the mean percentage of acini showing MUC2 gene expression in the four placebo-treated CF subjects was significantly higher for serous (80.5 +/- 12.7 per cent; P < 0.05, t-test), but not for mucous acini (53.1 +/- 16.8 per cent; P = 0.38). In CF and non-CF groups, where present, MUC2 positivity was strongly expressed and constituted approximately 84 per cent of the cell area in serous acini, whereas it was less obvious and was confined to the perinuclear area of cells in mucous acini. A significantly greater proportion of the surface epithelium was positive for MUC2 mRNA transcripts in the CF subjects (89.0, +/- 1.4 per cent) than in the surgically resected tissues of the four non-CF subjects (19.4, +/- 4.0 per cent) (P = 0.02). In the eight CFTR-cDNA-treated subjects, there was an overall trend to reduction, but no statistically significant alteration of MUC2 gene expression. It is concluded that the MUC2 gene is expressed at three- to four-fold higher levels in CF nasal mucosa than in non-CF nasal tissue and that it is expressed in a variety of cells additional to submucosal mucus-secreting glands.

Increases in IL-12 messenger RNA+ cells accompany inhibition of allergen-induced late skin responses after successful grass pollen immunotherapy

IL-12, a novel cytokine produced by tissue macrophages and B lymphocytes, stimulates proliferation of TH1-type T lymphocytes. We recently showed that in patients with summer hay fever, immunotherapy was effective and was associated with inhibition of allergen-induced late skin responses and increases in local interferon-gamma messenger RNA-positive cells. In this study 10 patients were reassessed after 4 years of immunotherapy and compared with 10 untreated patients with hay fever. Intradermal grass pollen challenge was performed, the late response was measured, and biopsies were performed at 24 hours. In situ hybridization of biopsy sections was performed by using a riboprobe coding for IL-12 mRNA. When immunotherapy and control subjects were compared, there was a marked reduction in the size of the late skin response (p = 0.0001). Significant increases in allergen-induced IL-12 mRNA+ cells in cutaneous biopsy specimens occurred only in the immunotherapy-treated group (all 10 patients, p = 0.002). At allergen-challenged sites, IL-12+ cells correlated positively with interferon-gamma + cells (r = 0.64, p < 0.05) and inversely with IL-4+ cells (r = -0.67, p < 0.05). The principal cell source (55% to 80%) of IL-12 message was the tissue macrophage (CD68+ cells). We suggest that IL-12 may promote TH1 responses and inhibit late-phase responses after successful immunotherapy.

RANTES in human allergen-induced rhinitis: cellular source and relation to tissue eosinophilia

Human allergen-induced rhinitis is associated with recruitment and activation of CD4+ T lymphocytes and eosinophils. RANTES is a novel CC chemokine that is a potent chemoattractant for both memory T cells and eosinophils. We therefore investigated RANTES in the nasal mucosa after local allergen provocation. Nasal lavage was performed, and biopsies from the inferior nasal turbinate were taken from 14 atopic, seasonal rhinitic patients and seven normal subjects for as long as 6 h after challenge with a grass pollen extract and after a control (allergen diluent) challenge. In five of seven rhinitics tested, radioimmunoassay of nasal fluid demonstrated increases in RANTES at 2 to 4 h (p < 0.05). Nasal allergen challenge provoked significant increases in RANTES mRNA (p = 0.0015) and protein (p = 0.01) containing cells in the nasal submucosa at 6 h. No changes were observed in normal subjects. Increases in RANTES mRNA+ cells correlated with the associated increases in eosinophils (r = 0.78, p = 0.001). Colocalization studies revealed that the majority of RANTES mRNA+ cells were macrophages (51%) followed by eosinophils (15%), T lymphocytes (11%), and mast cells (3%). Our results demonstrate that allergen-induced rhinitis is associated with release of RANTES and upregulation of RANTES mRNA and protein+ cells, predominantly macrophages, in the nasal mucosa. RANTES synthesis, release, or receptor antagonism may represent a potential target for antiallergy treatment.