The early history of the eosinophil.

In 1879 Paul Ehrlich published his technique for staining blood films and his method for differential blood cell counting using coal tar dyes and mentions the eosinophil for the first time. Eosin is a bright red synthetic dye produced by the action of bromine on fluorescein and stains basic proteins due to its acidic nature. It was discovered in 1874 by Heinrich Caro, Director of the German chemical company Badische Anilin- und Soda-Fabrik. Ehrlich introduced the term 'eosinophil' to describe cells with granules (which he called alpha-granules) having an affinity for eosin and other acid dyes. He also observed black-staining, indulinophilic, beta-granules in bone marrow-derived eosinophils, which were probably immature crystalloid granules in eosinophil myelocytes. Ehrlich described the features of the alpha-granule and the cell's distribution in various species and tissues. He speculated correctly that the alpha-granule contents were secretory products and described several causes of eosinophilia including asthma, various skin diseases, helminths and reactions to medications. However, the cell was almost certainly observed by others before Ehrlich. In 1846 Thomas Wharton Jones (1808-1891) described 'granule blood cells' in the lamprey, frog, fowl, horse, elephant and man. He 'borrowed' the term granule cell from Julius Vogel (1814-1880) who had observed similar cells in inflammatory exudates. Vogel in turn was aware of the work of the Gottlieb (Théophile) Gluge (1812-1898) who used the term 'compound inflammatory globules' to describe cells in pus and serum. Almost 20 years before Ehrlich developed his staining methods, Max Johann Sigismund Schultze (1825-1874) performed functional experiments on coarse granular cells using a warm stage microscopic technique and showed they had amoeboid movement and phagocytic abilities. Although these early investigators recognised distinct granular cells Ehrlich's use of stains was a landmark contribution, which heralded modern studies on eosinophils and other blood leucocytes.

Elevations in T-helper-2-initiating cytokines (interleukin-33, interleukin-25 and thymic stromal lymphopoietin) in lesional skin from chronic spontaneous ('idiopathic') urticaria.

BACKGROUND: The mechanism of wealing in chronic spontaneous urticaria (CSU) is largely unknown. We previously demonstrated increased expression of T-helper 2 [interleukin (IL)-4 and IL-5] cytokines in skin biopsies from CSU. This suggested that Th2-initiating cytokines [IL-33, IL-25 and thymic stromal lymphopoietin (TSLP)], released through innate immune mechanisms, may play a role in pathogenesis. OBJECTIVES: To identify Th2-initiating cytokines in lesional and nonlesional skin from patients with CSU and to compare the results with a control group. METHODS: Paired biopsies (one from a 4-8 h spontaneous weal and one from uninvolved skin) were taken from eight patients with CSU and nine control subjects, and studied by immunohistochemistry and confocal microscopy. RESULTS: There were increases in IL-4(+) and IL-5(+) cells in lesional skin vs. controls (P = 0·03 and P < 0·001, respectively) and marked elevations in the numbers of IL-33(+), IL-25(+) and TSLP(+) cells in the dermis of lesional skin vs. both nonlesional skin (P = 0·002, P = 0·01 and P = 0·04, respectively) and controls (P = 0·001, P < 0·001 and P = 0·005, respectively). There was also a correlation between the numbers of IL-33(+) and IL-25(+) cells (r = 0·808, P = 0·015). IL-33 localized to CD31(+) endothelial cells, CD90(+) fibroblasts, CD68(+) macrophages and tryptase(+) mast cells, whereas IL-25 was expressed by epithelial cells, mast cells and major basic protein-positive eosinophils. IL-33 and IL-25 were constitutively expressed in the epidermis of both controls and patients with CSU. CONCLUSIONS: Increased expression of Th2-initiating cytokines in lesional skin in CSU suggests that innate pathways might play a role in the mechanism of wealing. As Th2-initiating cytokines play a role in mast cell activation, inflammation and vascular leakage in CSU, these findings may also have therapeutic implications.

Calcitonin gene-related peptide and vascular endothelial growth factor are expressed in lesional but not uninvolved skin in chronic spontaneous urticaria.

BACKGROUND: The mechanisms for producing weals in chronic spontaneous (idiopathic) urticaria (CSU) are incompletely understood. Leucocyte infiltration with vascular leakage and expression of the potent vasoactive agents' calcitonin gene-related peptide (CGRP) and vascular endothelial growth factor (VEGF) are features of late-phase allergic skin reactions, previously proposed as a model of CSU. OBJECTIVE: To measure CGRP and VEGF expression in lesional and non-lesional skin from CSU patients and to compare results with a control group. METHODS: Eight paired biopsies (one from 4-8 h spontaneous weals and one from uninvolved skin) were taken from eight patients with CSU and nine control subjects and studied by immunohistochemistry and confocal microscopy. RESULTS: Lesional skin in CSU contained significantly more CGRP+ and VEGF+ cells than non-lesional skin. No significant differences were observed in CGRP and VEGF expression between non-lesional skin and controls. In lesional skin, VEGF and CGRP co-localised to UEA-1+ blood vessels. CGRP was also expressed by neutrophils and eosinophils and to a lesser extent by CD90(+) fibroblasts, mast cells, CD3(+) and CD68(+) cells. CGRP and VEGF expression was not related to the duration of disease. CONCLUSION AND CLINICAL RELEVANCE: Increased expression of CGRP and VEGF in lesional, but not uninvolved, skin indicates that these potent vasoactive agents may play a role in wealing and tissue oedema in CSU so representing novel targets in therapy.

Elevations in vascular markers and eosinophils in chronic spontaneous urticarial weals with low-level persistence in uninvolved skin.

BACKGROUND: In chronic spontaneous urticaria (CSU) mast cell activation together with inflammatory changes in the skin are well documented and may play an important role in mechanisms of tissue oedema. OBJECTIVES: To confirm and extend these observations by measuring microvascular markers, leucocytes and mast cell numbers in lesional and uninvolved skin and to compare findings with a control group. METHODS: Paired biopsies (one from 4-8-h spontaneous weals and one from uninvolved skin) were taken from eight patients with CSU and nine control subjects and studied using immunohistochemistry and confocal microscopy using the lectin Ulex europaeus agglutinin 1 (UEA-1). RESULTS: Lesional skin in CSU contained significantly more CD31+ endothelial cells; CD31+ blood vessels, neutrophils, eosinophils, basophils and macrophages; and CD3+ T cells than nonlesional skin. Increased vascularity was confirmed by confocal imaging using the lectin UEA-1. Uninvolved skin from CSU contained significantly more CD31+ endothelial cells, CD31+ blood vessels and eosinophils compared with the control subjects. There was a threefold increase in mast cell numbers when CSU was compared with controls but no difference was observed between lesional and uninvolved skin. CONCLUSIONS: Increased vascular markers together with eosinophil and neutrophil infiltration are features of lesional skin in CSU and might contribute to tissue oedema. Eosinophils and microvascular changes persist in uninvolved skin, which, together with increased mast cells, suggests that nonlesional skin is primed for further wealing.

Immunotherapy is allergen-specific: a double-blind trial of mite or timothy extract in mite and grass dual-allergic patients.

BACKGROUND: One hundred years ago, Noon [Lancet 1911;1:1572-1573], using conjunctival provocation testing (CPT), was the first to demonstrate the effectiveness of subcutaneous immunotherapy (SCIT) in grass-allergic subjects with hay fever. In this centenary year, we present data that, by use of CPT and allergen-specific IgG, replicate this observation and additionally confirm the allergen specificity of SCIT by using a double-blind design employing either grass or mite SCIT in dual grass- and mite-allergic individuals. METHODS: Twenty adults (11 females) with perennial rhinoconjunctivitis and exacerbation of symptoms during the grass pollen season and in the autumn had immediate skin and conjunctival sensitivity and raised specific IgE to both Dermatophagoides farinae and Phleum pratense. Participants were randomly assigned to either timothy or D. farinae immunotherapy for 3 years. CPT and specific IgG tests to both allergens were performed annually. After 3 years, subjects gave their blinded overall evaluation. RESULTS: Six mild-to-moderate general reactions occurred in 2 timothy- and 4 mite-treated patients. Four of these patients and 2 other patients withdrew from the study. Seven patients in each group completed the study. After 3 years of immunotherapy, the timothy CPT threshold concentration had increased 16- fold in timothy-treated patients (p < 0.05; between-group change, p < 0.05). The increase in the mite CPT threshold in mite- compared to grass-treated patients was 31-fold (p < 0.05). The overall assessment of conjunctival sensitivity was highly significant in favour of treatment (p < 0.015), as was that of allergen-specific IgG (p < 0.0001). CONCLUSIONS: Allergen immunotherapy is allergen species-specific, as judged by decreased conjunctival sensitivity and changes in allergen-specific IgG concentrations.

Early production of thymic stromal lymphopoietin precedes infiltration of dendritic cells expressing its receptor in allergen-induced late phase cutaneous responses in atopic subjects.

BACKGROUND: Thymic stromal lymphopoietin (TSLP) is an interleukin (IL)-7-like cytokine that triggers dendritic cell-mediated T helper (Th)2 inflammatory responses through a receptor consisting of a heterodimer of the IL-7 receptor alpha (IL-7Ralpha) chain and the TSLP receptor (TSLPR), which resembles the cytokine receptor common gamma chain. Dendritic cells activated by TSLP prime development of CD4(+) T cells into Th2 cells contributing to the pathogenesis of allergic inflammation. We hypothesized that allergen exposure induces expression of TSLP and results in recruitment of TSLPR bearing cells in the cutaneous allergen-induced late-phase reaction (LPR) in atopic subjects. METHODS: Skin biopsies were obtained from atopic subjects (n = 9) at various times after cutaneous allergen challenge. In situ hybridization and immunohistochemistry were used to determine TSLP mRNA expression and to measure infiltration of TSLPR(+) DC in skin LPR. RT-PCR and flow cytometry were employed to analyse TSLPR expression on isolated blood DC. RESULTS: Allergen-induced skin TSLP expression occurred as early as 1 h after allergen challenge, whereas TSLPR(+) and CD11c(+) cells infiltrated relatively late (24-48 h). The majority of TSLPR(+) cells were DC co-expressing blood DC antigen-1 (BDCA-1) or BDCA-2. Freshly isolated blood DC expressed both TSLPR and IL-7Ralpha chains. Maturation and stimulation with TSLP or polyriboinosinic-polyribocytidylic acid in vitro upregulated the expression of both TSLPR and IL-7Ralpha chains in DC but not in chemoattractant receptor-homologous molecule expressed on Th2 cells(+) CD4(+) T cells. CONCLUSION: The data suggest that TSLP plays a role in augmenting, through DC recruitment and activation, the development of Th2-type T cells in allergic inflammation.

Alcohol consumption is not protective for systemic lupus erythematosus.

OBJECTIVE: Several studies have suggested that alcohol drinking is protective for the development and progression of systemic lupus erythematosus (SLE). However, a protopathic bias might also explain this apparent association. Our objective was to investigate the association between alcohol consumption and incidence of SLE in a data set that has information on both current and pre-diagnostic alcohol consumption. METHODS: We performed an Internet-based case-control study of SLE. Cases were diagnosed within 5 years of the study and met > or =4 American College of Rheumatology criteria for SLE. The control participants were tightly matched to cases on demographic and socio-economic characteristics using a propensity score. Participants completed an online exposure assessment. We used conditional logistic regression analyses to test the association of current and pre-diagnostic alcohol consumption with SLE. RESULTS: The sample comprised 114 cases with SLE and 228 matched controls. Current drinking (>2 days per week) was inversely associated with SLE (OR 0.35, 95% CI 0.13 to 0.98). Having more than two drinks per day was also inversely associated with SLE (OR 0.41, 95% CI 0.18 to 0.93). However, alcohol consumption before SLE diagnosis was not associated with the risk of SLE (p> or =0.4). Analysis of the change in drinking habits showed that people with lupus were more likely to quit drinking before (OR 2.25, 95% CI 0.96 to 5.28) or after (OR 2.38, 95% CI 0.88 to 6.49) being given the SLE diagnosis. CONCLUSIONS: Our results show that alcohol consumption before SLE diagnosis is not associated with the risk for SLE, and that individuals who develop SLE are more likely to quit.

Skin reactivity and local cell recruitment in human atopic and nonatopic subjects by CCL2/MCP-1 and CCL3/MIP-1alpha.

BACKGROUND: Monocyte chemotactic protein (MCP-1/CCL2), the ligand for CCR2 and CCR5, and macrophage inflammatory protein-1alpha (MIP-1alpha/CCL3), the ligand for CCR1 and CCR5, are potent chemo-attractants in vitro and produce lesions in experimental animals, which resemble immediate and delayed-type hypersensitivity (DTH) reactions. CCL3 induces mononuclear cell and granulocyte infiltration in human atopic and nonatopic skin. Whether CCL2 (MCP-1) has comparable activity in man is uncertain as is the capacity of both the chemokines to elicit immediate- and DTH-like reactions in humans. METHODS: Inflammatory cells were counted by immunohistochemistry in 24 and 48-h skin biopsies from atopics and nonatopics after intradermal injection of CCL2 and CCL3. Immediate (15 min) wheals-and-flares and delayed (24 and 48 h) indurations were also recorded. RESULTS: Both chemokines induced immediate- (15 min) and delayed (24 and 48 h) reactions, which were associated with significant infiltrations of CD68+ macrophages, CD3+, CD4+ (but not CD8+) T cells, neutrophils, and eosinophils in biopsies from injection sites. CCL2, but not CCL3, also induced infiltration of basophils. Neither chemokine produced significant changes in the numbers of tryptase+ cutaneous mast cells. There were no differences in the pattern of skin reactivity or the numbers of infiltrating leukocytes in response to CCL2 and CCL3 between atopic and nonatopic subjects. In general, maximal infiltration of inflammatory cells was observed at the 24-h, rather than the 48-h, time point. CONCLUSIONS: CCL2 and CCL3 induce both immediate and delayed skin reactions in atopics and nonatopics, and evoke a similar profile of local T cell/macrophage and granulocyte recruitment which, in general, confirm previous in vitro findings and in vivo experimental animal data.

Effect of inhaled interleukin-5 on eosinophil progenitors in the bronchi and bone marrow of asthmatic and non-asthmatic volunteers.

BACKGROUND: Asthma is characterized by increases in mature eosinophils and their progenitors within the bronchus and bone marrow. IL-5 plays a key role in eosinophil development in the bone marrow and at the site of allergic inflammation. We therefore studied the effects of nebulized IL-5 on eosinophils, their progenitors and in situ haemopoiesis within the airway and bone marrow. METHODS: Nine atopic asthmatics and 10 non-atopic non-asthmatic control volunteers inhaled 10 microg of IL-5 or placebo via a nebulizer in a double-blind, randomized, cross-over study. Bronchoscopy, bone marrow aspiration and peripheral blood sampling were performed 24 h after nebulization. Four weeks later, volunteers inhaled the alternative solution and underwent a repeat bronchoscopy and bone marrow aspiration. RESULTS: Inhalation of IL-5 significantly decreased CD34(+)/IL-5Ralpha mRNA(+) cells within the bronchial mucosa and the percentage of CD34(+) cells that were CCR3(+) within the bone marrow of atopic asthmatic, but not control, volunteers. Inhalation of IL-5 also induced a significant increase in bronchial mucosal eosinophils in the non-atopic non-asthmatic control volunteers, but not in the asthmatics. IL-5 had no effect on spirometry or airways hyper-reactivity in either group. CONCLUSIONS: Inhaled IL-5 modulated eosinophil progenitor numbers in both the airways and bone marrow of asthmatics and induced local eosinophilia in non-asthmatics.

Airway expression of calcitonin gene-related peptide in T-cell peptide-induced late asthmatic reactions in atopics.

BACKGROUND: The mechanisms of late asthmatic reactions provoked in atopic asthmatics by allergen-derived T-cell peptide epitopes remain unclear. Previous studies showed no changes in airway eosinophils or mast cell products after peptide challenge. In the present study our aim was to measure calcitonin gene-related peptide (CGRP), neurokinin (NK)-A, and substance P (SP) in bronchoalveolar lavage fluid and bronchial biopsies (BB) after inhalation of allergen-derived T-cell peptide epitopes since these neuropeptides (NP) had not previously been evaluated in this chronic asthma model. METHODS: Bronchoscopy, with BB and bronchoalveolar lavage (BAL), was performed in 24 cat-allergic subjects 6 h after inhalation of Fel d 1-derived peptides. Neuropeptides were measured in BAL by enzyme-linked immunosorbent assay and CGRP expression in the airways was assessed by immunohistochemistry and confocal microscopy. RESULTS: Twelve subjects (termed 'responders') developed isolated late reactions. Calcitonin gene-related peptide, but not NK-A or SP, was significantly elevated in BAL in responders only. Biopsy studies showed that in virtually all responders peptide challenge induced marked increases in CGRP immunoreactivity in bronchial epithelial cells, infiltrating submucosal cells and in association with airway smooth muscle. Double immunostaining indicated that CGRP colocalized predominantly to CD3+/CD4+ and CD68+ submucosal inflammatory cells. CONCLUSION: Calcitonin gene-related peptide, a potent vasodilator, is markedly up-regulated in the airways of atopic asthmatics during late-phase reactions provoked by inhalation of allergen-derived T-cell peptides.

An extract of Timothy-grass pollen used as sublingual immunotherapy for summer hay fever.

Grazax is a lyophilisate of an extract of Timothy-grass pollen (Phleum pratense) administered by the sublingual route to induce desensitization (or hyposensitization) to grass pollen in subjects with hay fever. Since allergen avoidance measures are limited in hay fever sufferers, present treatment, at least in the United Kingdom, is almost always by symptomatic medication. The effectiveness of symptomatic treatment in hay fever is variable and depends on patient compliance and the judicious prescribing of antihistamines and anti-inflammatory preparations either alone or in combination. Desensitization (hyposensitization or specific immunotherapy) by subcutaneous injection has been shown to be very efficacious and is used for patients who do not adequately respond to drug treatment. A rare side effect of desensitizing injections is anaphylaxis, and so use is limited to specialized centers. For these reasons there has been considerable interest in specific immunotherapy by the sublingual route. Grazax has recently been approved in the United Kingdom. It is commenced at least four months prior to the expected start of the grass pollen season and in line with injection immunotherapy treatment will be recommended for a period of three years with annual reviews to assess patient outcomes. Grazax grass allergen tablets are well tolerated in patients with grass pollen allergy with most adverse events being mild local reactions. There have been no instances of anaphylaxis. In randomized double-blind placebo controlled trials Grazax reduces symptoms and medication scores in adults with hay fever. The long-term effects of Grazax are currently being investigated.

100 years of 'Allergy': can von Pirquet's word be rescued?

Summary It is 100 years since Clemens von Pirquet wrote his classic paper introducing the term 'allergy'. Although the word is no longer used in the way he intended, his concept of 'changed reactivity' laid the foundation for the modern science of immunology.

Induction of interleukin-10 and suppressor of cytokine signalling-3 gene expression following peptide immunotherapy.

BACKGROUND: Allergen-derived (T cell epitope) peptides may be safer for immunotherapy than native allergen, as they do not cross-link immunoglobulin (Ig)E. However, HLA polymorphism results in multiple potential epitopes. Synthetic peptides of phospholipase (PL) A(2) were selected for a peptide vaccine, on the basis of binding affinity for commonly expressed HLA-DR molecules. OBJECTIVE: To evaluate treatment with an HLA-DR-based PLA(2) peptide vaccine in subjects with mild honeybee allergy in an open, controlled study. METHODS: Twelve volunteers with allergy to bee venom received nine intradermal injections of PLA(2) peptides, with six untreated subjects serving as controls. Outcome was assessed by the size of the late-phase cutaneous reaction to allergen, peripheral blood mononuclear cell (PBMC) proliferation, cytokine release, and expression of genes associated with immune regulation. RESULTS: Subjects receiving peptides showed a decrease in the magnitude of the late-phase cutaneous reaction to bee venom compared with controls (P=0.03). The proliferation of venom-stimulated PBMCs decreased in treated subjects compared with controls (P=0.01). Peptide treatment reduced the production of IL-13 by PLA(2)-stimulated PBMCs (P<0.01) and IFN-gamma (P<0.01), and increased the production of IL-10 (P=0.02). Transcription of the suppressor of cytokine signalling (Socs)3 gene was significantly increased following therapy. A transient, but modest, increase in allergen-specific IgG was also observed. CONCLUSION: HLA-DR-based T cell epitopes modify surrogate markers associated with successful immunotherapy and induction of immune regulation, supporting the concept that this form of treatment may be efficacious in human allergic disease.

The effect of Fel d 1-derived T-cell peptides on upper and lower airway outcome measurements in cat-allergic subjects.

BACKGROUND: We previously showed that overlapping Fel d 1-derived T-cell peptides inhibited surrogate markers of allergy (i.e. early and late-phase skin reactions and T-cell function) in cat allergic subjects. The present pilot study was designed to determine whether this treatment affected clinically relevant outcome measurements such as the allergen-induced nasal and bronchial reactions, and asthma/rhinitis quality of life (QOL). METHODS: Sixteen cat-allergic asthmatic subjects who gave a dual (early and late) asthmatic response (DAR) to inhaled cat allergen were randomly assigned to receive either Fel d 1 peptides (approximately 300 mug in increasing, divided doses) or placebo (8 active : 8 placebo). Twelve single early responders (SER) were also studied in an open fashion design. Allergen-induced bronchial and nasal measurements as well as the QOL was measured at baseline, 4-8 weeks (follow-up 1 (FU1)) and 3-4 months (FU2). RESULTS: In the active, but not placebo, group there were significant decreases in the late asthmatic reaction (LAR) to whole cat dander (P = 0.03) at FU2 but with no between group difference. There were also significant improvements in asthma quality of life (QOL) scores [asthma-activity limitation (P = 0.014); rhinitis-sleep (P = 0.024), non-nose/non-eye symptoms (P = 0.031), nasal problems (P = 0.015)]. In the open study Fel d 1 peptide treatment resulted in significant decreases in number of sneezes (P = 0.05), weight of nasal secretions (P = 0.04) and nasal blockage (P = 0.01) following allergen challenge. CONCLUSIONS: Multiple, short, overlapping Fel d 1 T-cell peptides have potential for inhibiting upper and lower airway outcome measurements in cat allergic patients. Larger, dose-ranging, studies are required before firm conclusions on clinical efficacy of peptide allergen therapy can be made.

Cat allergen peptide immunotherapy reduces CD4(+) T cell responses to cat allergen but does not alter suppression by CD4(+) CD25(+) T cells: a double-blind placebo-controlled study.

BACKGROUND: We have previously described both modification of allergen immunotherapy using peptide fragments, and reduced regulation of allergen stimulated T cells by CD4(+) CD25(+) T cells from allergic donors when compared with nonallergic controls. It has been suggested that allergen immunotherapy induces regulatory T cell activity: we hypothesized that allergen peptide immunotherapy might increase suppressive activity of CD4(+) CD25(+) T cells. OBJECTIVE: To examine cat allergen-stimulated CD4 T cell responses and their suppression by CD4(+) CD25(+) T cells before and after cat allergen peptide immunotherapy in a double-blind placebo-controlled study. METHODS: Peripheral blood was obtained and stored before and after peptide immunotherapy or placebo treatment. CD4(+) and CD4(+) CD25(+) were then isolated by immunomagnetic beads and cultured with allergen in vitro. RESULTS: Comparing cells from blood taken before with that after peptide immunotherapy there was a significant reduction in both proliferation and IL-13 production by allergen-stimulated CD4+ T cells, whereas no change was seen after placebo. CD4(+) CD25(+) T cells suppressed both proliferation and IL-13 production by CD4(+) CD25(-) T cells before and after therapy but peptide therapy was not associated with any change in suppressive activity of these cells. CONCLUSION: Allergen peptide immunotherapy alters T cell response to allergen through mechanisms other than changes in CD4(+) CD25(+) T cell suppression.

Interactions between eotaxin, histamine and mast cells in early microvascular events associated with eosinophil recruitment to the site of allergic skin reactions in humans.

BACKGROUND: The mechanism whereby allergen induces eotaxin expression at the site of allergic inflammation is incompletely understood. Structural cells, including endothelial cells, are a major source of eotaxin. OBJECTIVE: We have investigated, in vivo and in vitro, the relationship between mast cell activation and the expression of eotaxin (eotaxin 1) by endothelial cells. METHODS: The effects of intradermal allergen challenge and histamine injection on eotaxin mRNA and protein generation were studied in atopic subjects using immunofluorescence, immunohistochemistry and in situ hybridization. Histamine-induced expression of eotaxin mRNA and protein by endothelial cells was also measured, as was histamine-induced eosinophil adhesion to cultured endothelial cells. RESULTS: A rapid increase in degranulating cutaneous mast cells, together with a concomitant increase in eosinophils, was observed 60 min after allergen challenge. This was accompanied by the appearance of immunoreactive eotaxin that peaked at 1 h around blood vessels and at 3 h within the tissue. Intradermal histamine injection produced an increase in the number of eotaxin+ cells in the tissues, which was maximal at the 3-h time-point. In vitro, endothelial cells produced eotaxin mRNA and protein product in a dose- and time-dependent fashion following incubation with histamine, an effect that was blocked by levocetirizine. Pre-incubation of endothelial cells with histamine also induced a significant increase in eosinophil adherence, an effect that was inhibited with an anti-eotaxin blocking monoclonal antibody. CONCLUSION: The antigen-induced expression of eotaxin by endothelial cells and the adherence and subsequent migration of eosinophils from the microvasculature to the tissues are rapid events partially under the control of histamine released from degranulating mast cells.

Intravenous anti-IL-5 monoclonal antibody reduces eosinophils and tenascin deposition in allergen-challenged human atopic skin.

Anti-IL-5 monoclonal antibody (mepolizumab) reduces baseline bronchial mucosal eosinophils and deposition of extracellular matrix proteins in the reticular basement membrane in mild asthma. Here we report the effect of anti-IL-5, in the same patients, on allergen-induced eosinophil accumulation, tenascin deposition (as a marker of repair and remodelling) and the magnitude of the late-phase allergic cutaneous reaction. Skin biopsies were performed in 24 atopic subjects at allergen- and diluent-injected sites before 6 and 48 h after, three infusions of a humanized, monoclonal antibody against IL-5 (mepolizumab) using a randomized double-blind, placebo-controlled design. Anti-IL-5 significantly inhibited eosinophil infiltration in 6 h and 48 h skin biopsies as well as the numbers of tenascin immunoreactive cells at 48 h. In contrast, anti-IL-5 had no significant effect on the size of the 6 or 48 h late-phase cutaneous allergic reaction. This study (a) suggests that eosinophils are unlikely to cause the redness, swelling, and induration characteristic of the peak (6 h) late-phase cutaneous allergic reaction and (b) shows that decreases in tenascin positive cells at 48 h correlates with reduction of eosinophils, so providing further evidence of involvement in remodelling processes associated with allergic inflammation.

Cyclosporin A, apoptosis of BAL T-cells and expression of Bcl-2 in asthmatics.

The late asthmatic reaction is characterised by elevated numbers of interleukin-4/interleukin-5/CD4-positive T-helper cells type 2 in bronchoalveolar lavage fluid (BALF). Cyclosporin A (CsA) is known to inhibit T-cell proliferation, induce apoptosis of CD4-positive T-cells and downregulate cytokine gene expression. It was assessed whether CsA-induced inhibition of the late asthmatic reaction was associated with apoptosis of BALF T-lymphocytes and other cell types, as well as expression of the antiapoptotic protein B-cell leukaemia/lymphoma 2 gene product (Bcl-2). BALF cells were obtained from asthmatics at baseline and 24 h after allergen-inhalation challenge following prior administration of CsA (n=13) or placebo (n=11). The number of apoptotic CD3-positive T-lymphocytes increased in the CsA but not the placebo group. The numbers of Bcl-2-positive cells were significantly reduced in the CsA but not the placebo group. The majority of Bcl-2-positive cells were CD3-positive T-lymphocytes. The beneficial effect of cyclosporin A in asthma may be related to its inhibitory effect on the late asthmatic reaction via induction of T-cell apoptosis and decreased B-cell leukaemia/lymphoma 2 gene product levels.

Effect of T-cell peptides derived from Fel d 1 on allergic reactions and cytokine production in patients sensitive to cats: a randomised controlled trial.

BACKGROUND: Some patients with asthma who are allergic to cats and are injected intradermally with short, overlapping, T-cell peptides derived from Fel d 1 develop late asthmatic reactions to the peptides, which are associated with a reduction in late-phase skin reactions induced by whole allergens and bronchial hyporesponsiveness to the peptides on the second injection. We aimed to ascertain the effect of multiple injections on the magnitude of the early and late phase skin reactions to intact allergens. METHODS: After a 9-week run-in period, we randomly assigned patients with asthma and allergies to cats to receive either Fel d 1 peptides (90 microg in increasing divided doses) or placebo. The primary outcome was late-phase cutaneous reactions to whole cat dander. Outcomes were measured at baseline, 4-8 weeks, and 3-9 months. Analysis was by intention to treat. FINDINGS: 16 patients were randomly assigned to the peptides, and eight to placebo. All patients completed the course of injections. Four of the 16 patients on Fel d 1 peptides had initial late asthmatic reactions, but could be desensitised to the higher dose of peptide. Patients in the peptide group but not the placebo group had a significant reduction in the size of their late reaction to whole cat dander between baseline and both follow-ups, but the difference between groups was not significant (first follow-up, difference -422.8 mm(2) [95% CI -1115.0 to 269.4], p=0.43; second follow-up -1180.8 mm(2) [-2216.8 to -144.8], p=0.058). The size of the late reaction to Fel d 1 significantly differed between treatment groups at both follow-ups. At second follow-up, the size of the early reaction to Fel D 1, but not to whole cat dander was significantly reduced in those on peptides compared with those on placebo. The concentration of interferon gamma and of interleukin 4 and 13, and the amount of proliferation, significantly decreased between baseline and second follow-up, and the concentration of interleukin 10 was significantly higher in patients on peptides, however, none of these values differed significantly between groups. Patients on peptides had a significantly greater decrease in the concentration of interferon gamma and interleukin 13, and in the amount of proliferation between baseline and first follow-up than did those on placebo. INTERPRETATION: Several, short, overlapping Fel d 1 T-cell peptides have potential in treatment of cat allergy.