RESUMO
BACKGROUND: The fractional exhaled nitric oxide (FeNO) is a quantitative, noninvasive and safe measure of airways inflammation that may complement the assessment of asthma. Elevations of FeNO have recently been found to correlate with allergic sensitization. Therefore, FeNO may be a useful predictor of atopy in the general population. We sought to determine the diagnostic accuracy of FeNO in predicting atopy in a population-based study. METHODS: We conducted a cross-sectional study in an age- and sex- stratified random sample of 13 to 15 year-olds in two communities in Peru. We asked participants about asthma symptoms, environmental exposures and sociodemographics, and underwent spirometry, assessment of FeNO and an allergy skin test. We used multivariable logistic regression to model the odds of atopy as a function of FeNO, and calculated area-under-the-curves (AUC) to determine the diagnostic accuracy of FeNO as a predictor of atopy. RESULTS: Of 1441 recruited participants, 1119 (83%) completed all evaluations. Mean FeNO was 17.6 ppb (SD=0.6) in atopics and 11.6 ppb (SD=0.8) in non-atopics (p<0.001). In multivariable analyses, a FeNO>20 ppb was associated with an increase in the odds of atopy in non-asthmatics (OR=5.3, 95% CI 3.3 to 8.5) and asthmatics (OR=16.2, 95% CI 3.4 to 77.5). A FeNO>20 ppb was the best predictor for atopy with an AUC of 68% (95% CI 64% to 69%). Stratified by asthma, the AUC was 65% (95% CI 61% to 69%) in non-asthmatics and 82% (95% CI 71% to 91%) in asthmatics. CONCLUSIONS: FeNO had limited accuracy to identify atopy among the general population; however, it may be a useful indicator of atopic phenotype among asthmatics.
Assuntos
Testes Respiratórios/métodos , Hipersensibilidade Imediata/diagnóstico , Hipersensibilidade Imediata/metabolismo , Óxido Nítrico/análise , Adolescente , Biomarcadores/análise , Estudos Transversais , Expiração , Feminino , Humanos , Hipersensibilidade Imediata/epidemiologia , Masculino , Peru/epidemiologia , Prevalência , Reprodutibilidade dos Testes , Medição de Risco , Sensibilidade e EspecificidadeRESUMO
It is unclear if the relationship of total serum IgE with asthma varies with degree of urbanisation. We hypothesised that the relationship of total serum IgE to asthma is more pronounced in an urban versus a rural environment. We enrolled 1441 children aged 13-15 years in a peri-urban shanty town in Lima, Peru (n=725) and 23 villages in rural Tumbes, Peru (n=716). We asked participants about asthma and allergy symptoms, environmental exposures and sociodemographics; and performed spirometry, and exhaled nitric oxide and allergy skin testing. We obtained blood for total serum IgE in 1143 (79%) participants. Geometric means for total serum IgE were higher in Lima versus Tumbes (262 versus 192 kU·L(-1); p<0.001). The odds of asthma increased by factors of 1.6 (95% CI 1.3-2.0) versus 1.4 (95% CI 0.9-2.1) per log unit increase in total serum IgE in Lima versus Tumbes, respectively. Atopy was an effect modifier of the relationship of total serum IgE on asthma. Among atopics and non-atopics, the odds of asthma increased by a factor of 2.0 (95% CI 1.5-2.7) and 1.0 (95% CI 0.7-1.4) per log unit increase in total serum IgE, respectively. Total serum IgE was associated with atopic asthma but not with non-atopic asthma. Urbanisation did not appear to be an effect modifier of this relationship.
Assuntos
Asma/sangue , Imunoglobulina E/sangue , Urbanização , Adolescente , Asma/epidemiologia , Estudos Transversais , Exposição Ambiental , Feminino , Humanos , Hipersensibilidade/metabolismo , Inflamação/metabolismo , Masculino , Óxido Nítrico/metabolismo , Razão de Chances , Peru/epidemiologia , Fatores de Risco , Testes Cutâneos , Classe SocialRESUMO
OBJECTIVE: To examine the relation between mouse allergen exposure and asthma in Puerto Rican children. METHODS: Mus m 1, Der p 1, Bla g 2, and Fel d 1 allergens were measured in dust samples from homes of Puerto Rican children with (cases) and without (controls) asthma in Hartford, CT (nâ=â449) and San Juan (SJ), Puerto Rico (nâ=â678). Linear or logistic regression was used for the multivariate analysis of mouse allergen (Mus m 1) and lung function (FEV(1) and FEV(1)/FVC) and allergy (total IgE and skin test reactivity (STR) to ≥1 allergen) measures. RESULTS: Homes in SJ had lower mouse allergen levels than those in Hartford. In multivariate analyses, mouse allergen was associated with higher FEV(1) in cases in Hartford (+70.6 ml, 95% confidence interval (CI)â=â8.6-132.7 ml, Pâ=â0.03) and SJ (+45.1 ml, 95% CIâ=â -0.5 to 90.6 ml, Pâ=â0.05). In multivariate analyses of controls, mouse allergen was inversely associated with STR to ≥1 allergen in non-sensitized children (odds ratio [OR] for each log-unit increment in Mus m 1â=â0.7, 95% CIâ=â0.5-0.9, P<0.01). In a multivariate analysis including all children at both study sites, each log-increment in mouse allergen was positively associated with FEV(1) (+28.3 ml, 95% CIâ=â1.4-55.2 ml, Pâ=â0.04) and inversely associated with STR to ≥1 allergen (OR for each log-unit increment in Mus m 1â=â0.8, 95% CIâ=â0.6-0.9, P<0.01). CONCLUSIONS: Mouse allergen is associated with a higher FEV(1) and lower odds of STR to ≥1 allergen in Puerto Rican children. This may be explained by the allergen itself or correlated microbial exposures.
Assuntos
Alérgenos/imunologia , Asma/imunologia , Asma/fisiopatologia , Pulmão/imunologia , Pulmão/fisiopatologia , Animais , Asma/epidemiologia , Estudos de Casos e Controles , Criança , Cidades/estatística & dados numéricos , Poeira/imunologia , Humanos , Pulmão/fisiologia , Masculino , Camundongos , Análise Multivariada , Porto Rico/epidemiologiaRESUMO
BACKGROUND: Necator americanus Ancylostoma-secreted protein 2 (Na-ASP-2) is secreted by infective hookworm larvae on entry into human hosts. Vaccination of laboratory animals with recombinant Na-ASP-2 provides significant protection against challenge infections. In endemic areas antibodies to Na-ASP-2 are associated with reduced risk of heavy N americanus infections. OBJECTIVE: To assess the safety and immunogenicity of recombinant Na-ASP-2 adjuvanted with Alhydrogel in healthy Brazilian adults previously infected with N americanus. METHODS: Participants were randomized to receive Na-ASP-2 or hepatitis B vaccine. Major IgG and IgE epitopes of the Na-ASP-2 molecule were mapped by using sera from these same subjects. Seroepidemiologic studies in adults and children residing in hookworm-endemic areas were conducted to assess the prevalence of IgE responses to Na-ASP-2. RESULTS: Vaccination with a single dose of Na-ASP-2 resulted in generalized urticarial reactions in several volunteers. These reactions were associated with pre-existing Na-ASP-2-specific IgE likely induced by previous hookworm infection. Surveys revealed that a significant proportion of the population in hookworm-endemic areas had increased levels of IgE to Na-ASP-2. Epitope mapping demonstrated sites on the Na-ASP-2 molecule that are uniquely or jointly recognized by IgG and IgE antibodies. CONCLUSION: Infection with N americanus induces increased levels of total and specific IgE to Na-ASP-2 that result in generalized urticaria on vaccination with recombinant Na-ASP-2. These data advance knowledge of vaccine development for helminths given their propensity to induce strong T(H)2 responses. Study data highlight the important differences between the immune responses to natural helminth infection and to vaccination with a recombinant helminth antigen.
Assuntos
Antígenos de Helmintos/efeitos adversos , Proteínas de Helminto/efeitos adversos , Necator americanus/imunologia , Necatoríase/prevenção & controle , Urticária/epidemiologia , Vacinas Sintéticas/efeitos adversos , Adolescente , Adulto , Animais , Antígenos de Helmintos/administração & dosagem , Antígenos de Helmintos/imunologia , Brasil/epidemiologia , Mapeamento de Epitopos , Feminino , Proteínas de Helminto/administração & dosagem , Proteínas de Helminto/imunologia , Humanos , Imunoglobulina E/sangue , Imunoglobulina G/sangue , Masculino , Pessoa de Meia-Idade , Necatoríase/epidemiologia , Necatoríase/imunologia , Estudos Soroepidemiológicos , Resultado do Tratamento , Urticária/etiologia , Vacinação/efeitos adversos , Vacinas Sintéticas/administração & dosagem , Vacinas Sintéticas/imunologia , Adulto JovemRESUMO
Several proteins of rubber latex have been recognized as allergens causing immediate hypersensitivity in humans. In this study, a bottom fraction membrane (BFM) protein preparation from Hevea brasiliensis trees grown in southern Thailand was used to detect specific IgE in four groups of serum samples. The first group included 170 samples of latex glove factory workers (LGWs); group 2 consisted of the sera of 35 health care workers (HCWs) who were repeatedly exposed to powdered latex gloves; groups 3 and 4 were 31 positive and 22 negative sera, respectively, obtained from Johns Hopkins University School of Medicine, Baltimore, USA, tested for IgE to latex allergen. It was found that 56/170 (33%), 5/35 (14%), 11/31 (35.5%) and 1/22 (4.5%) samples of the LGWs, HCWs, CAP+ and CAP- groups had significant IgE to the BFM proteins, respectively. However, of all subjects only one subject of group 1 had experienced allergic morbidity consisting of eczema, conjunctivitis and asthma. The IgE of this subject bound to a 55 kDa component in the rubber latex BFM preparation. Thus, this protein may be regarded as a novel, although minor, latex allergen. Further investigation is needed to characterize the component and to pinpoint its allergenic role.
Assuntos
Alérgenos/imunologia , Hevea , Hipersensibilidade ao Látex/imunologia , Proteínas de Plantas/imunologia , Alérgenos/isolamento & purificação , Fracionamento Celular , Luvas Protetoras/efeitos adversos , Setor de Assistência à Saúde , Pessoal de Saúde , Humanos , Interações Hidrofóbicas e Hidrofílicas , Imunoglobulina E/sangue , Hipersensibilidade ao Látex/sangue , Membranas , Exposição Ocupacional , Proteínas de Plantas/isolamento & purificação , Borracha/efeitos adversosRESUMO
Recurring reports of a highly allergenic 42-46-kDa protein in Hevea brasiliensis latex appeared to have been resolved with the discovery of a 43-kDa allergenic latex protein that was a homologue to patatin. However, the low to moderate prevalence of sensitization to the protein, designated Hev b 7, among latex-allergic patients could not adequately explain the frequent observations of the 42-46-kDa allergen. This led to the hypothesis that another, more allergenic protein of a similar molecular mass existed in Hevea latex. We report the isolation and purification of a 42.98-kDa latex glycoprotein showing homology to the early nodule-specific protein (ENSP) of the legumes Medicago sativa, Medicago truncatula, and Glycine max. The protein is allergenic, being recognized by immunoglobulin E (IgE) in sera from latex-allergic patients. The IgE epitope resides on the carbohydrate moiety of the protein, and the presence of a similar carbohydrate component on potato tuber patatin enables the latter to inhibit IgE binding to the ENSP homologue. The cDNA encoding the ENSP homologue was isolated by reverse transcription-PCR and cloned. The protein predicted from the cDNA sequence has 391 amino acids, the first 26 of which constitute a putative signal peptide. The deduced molecular mass of the mature protein is 40.40 kDa, while its isoelectric point is estimated at 5.0. The discrepancy between the predicted and observed molecular mass might be due to glycosylation, for which three N-sites on the protein are predicted. The purified protein showed lipase and esterase activities and may be involved in plant defense.