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Notes: To evaluate the association of various leukocytes with pulmonary resist ance and methacholine responsiveness, we induced pulmonary eosi-nophil-rich inflammation in IgE-sensitized (ovalbumin) Sprague Dawlcy rats. Sensitized rats were challenged with either relevant (OA) or irrele vant antigen by tracheal insufflation a) with no other treatment, b) in conjunction with intravenous Sephadex beads pretrcatment, or c) with antigen coupled covalently to Sepharose heads. About 24 h after antigen challenge, respiratory system resistance (Rrs), response to aerosolized methacholine, and pulmonary histopathology were evaluated. Challenge with OA, insufflation with Sepharose, and treatment with i. v. Sephadex all independently increased inflammatory cell infiltrates, but the combi nation of OA with the other agents did not significantly enhance the inflammatory response over OA alone. Interactive stepwise regression techniques were utilized to identify correlates for Rrs and methacholine responsiveness. Mononuclear cell score was a significant predictor (p 〈 0.1) for Rrs, and insufflation of Sepharose had a significant inde pendent effect on Rrs (p=. 01) above that predicted by mononuclear cell infiltrates. Conversely, eosinophil score and neutrophil score were not significant predictors for Rrs, and challenges with antigen or Sephadex had no significant independent effect on Rrs beyond that predicted from mononuclear cell infiltrates. Eosinophil score was the only significant histological predictor for methacholine responsiveness (p 〈0.001). Chal lenges with Sephadex, antigen and Sepharose did not significantly change methacholine responsiveness independently of the changes asso ciated with eosinophil infiltrates. These findings suggest that mononucle ar cells and eosinophils contribute to increases in airway resistance and responsiveness, respectively, following the induction of pulmonary inflammation by both allergic and non-allergic stimuli.

Notes: Asthma is one of the atopic diseases strongly associated with allergy. High aeroallergen exposure in the immediate postnatal period has been associated with higher risk of sensitization and chronic asthma. It is proposed that following in utero allergen sensitization, postnatal high dose allergen exposure localizes inflammation to the airways. In association with adjuvantizing effects of some virus infections, eosinophils and neutrophils are recruited which contribute to epithelial damage and the initiation of the remodelling process. Eventually, the latter processes lead to sufficient airway narrowing to manifest as the first symptoms of asthma. Thus, the immunopathology of asthma is fully established by the time of first symptoms and future strategies will need to identify those at risk of developing the disease before irreversible changes in the airways are established.

Notes: As part of a larger epidemiological study, 114 children with respiratory symptoms, born between 1978 and 1980, were skin-prick tested to Dermatophagoides pteronyssinus (DP), mixed grass pollens (G) and cat dander (C), and to histamine and saline controls (Bencard, U.K.) using 1 mm prick-lancets (Dome/Hollister-Stier), between July and September 1987 and again in October 1989. A weal ≥ 2 mm to one or more allergens was regarded as a positive result. Each child was tested by the same investigator on each occasion, using similar techniques. Three children were excluded from analysis as they had failed to respond to histamine testing on one of the two occasions. In 1987, of the 111 children analysed, 58 (52%) children were skin-test positive, and 53 (48%) skin-test negative, while in 1989 62 (56%) were positive and 49 (44%) negative. Twelve children (11%) changed status from negative to positive, while eight (7%) changed from positive to negative. For the group as a whole the percentage agreement between the results obtained 2 years apart was 82%. In comparison to previous studies a greater number of subjects in this population than expected changed atopic status. We therefore further examined the data from those who had changed status and classified as borderline those subjects with no difference in weal size of greater than 2 mm for any allergen between 1987 and 1989. Only five children then changed status from negative to positive, none from positive to negative and 15 demonstrated only borderline changes. The coefficients of repeatability for the 106 children who did not change status were 3.37 mm, 2.80 mm and 2.33 mm for D. pteronyssinus, mixed grass pollens and cat dander respectively. The good short-term repeatability of the testing method was demonstrated in a group of 29 similar children; the coefficients of repeatability were 0.38 mm for DP and G, and 0.72 mm for C. These data demonstrate that, in a population of children with respiratory symptoms, skin-prick testing within individuals is highly repeatable over the short term, but poorly repeatable over a 2 year period. However, the percentage agreement in skin-prick test status for the group as a whole was high (82%). While no child became unequivocally skin-test negative having been previously positive, a small number of children changed status from negative to unequivocally positive, suggesting a genuine but small (4%) increase in the prevalence of skin-test positivity in this population.

Notes: Recent in vitro studies suggest that IgE production in adults is co-ordinately regulated by negative signals from γIFN-producing CD4+ T-helper-1 (TH-1) and positive signals from IL-4 producing (TH-2) T-cells. Additionally, seroepidemiological evidence has pinpointed infancy as the period of maximum lifetime risk for T-cell sensitization to ubiquitous environmental antigens. The present study sought to elucidate the relationship between these observations, by examination of CD4+ T-cell function in normal children and those genetically at‘high risk’ for atopy, spanning the age range (up to 4 years) in which IgE responses to environmental allergens is typically manifest. Immunocompetent T-cell precursor frequencies (determined by cloning at limiting dilution) were markedly reduced in ‘high risk’ children relative to normals (0.53.0.29 vs 0.26.0.19; P= 0.0025). Consistent with reports from other laboratories employing bulk T-cell culture techniques, the γIFN producing capacity of CD4+ T-cell clones from both groups of children were markedly reduced relative to adults, and was lowest in the high risk group (P〈0.02). IL-4 production by CD4+ T-cell clones from the normal children was within the adult range, but again was significantly lower in the high risk group (P〈0.00005). This indicates that initial immune responses to environmental allergens in early childhood occur against a background of maturational ‘deficiency’ in CD4+ T-cell function, and suggests the possibility that variations in the rate of postnatal maturation of T-cell competence may be a contributing factor in the development of differing patterns of immunological responsiveness to environmental allergens.

Notes: Background Mast cell chymase has the potential to be an important mediator of inflammation and remodelling in the asthmatic lung. Previous studies have examined association between promoter polymorphism of the chymase gene (CMA1) and allergic phenotypes but the significance of this polymorphism is unclear. We have examined association of a CMA1 variant in relation to asthma in a large UK Caucasian family cohort.Methods A polymorphism of the CMA1 gene promoter (−1903G/A) was genotyped in 341 asthmatic families and in 184 non-asthmatic adults recruited from the UK PCR-RFLP based genotyping. Association with asthma diagnosis, atopy, specific and total IgE, and atopy and asthma severity was examined.Results Case–control studies did not reveal a significant difference in allele frequency between asthmatics and controls. A significant association was found between CMA1 genotypes and total IgE levels in subjects with self-reported eczema that remained significant after correction for multiple testing (median total serum IgE GG 297 kU/L, GA 144 kU/L, AA 48.4 kU/L, Pc=0.0032).Conclusion These data suggest that CMA1 promoter polymorphism does not contribute to asthma susceptibility or severity but may be involved in regulating IgE levels in patients with eczema.

Notes: Background  IL-4 by binding to its receptor (IL-4R) is essential for the development of airway inflammation present in asthma, through the induction of IgE synthesis in B cells and differentiation of T cells to a Th2 phenotype.Objective  To investigate the role of four common polymorphisms in the IL-4 (IL4-34CT and IL4-589CT) and IL-4Rα chain (IL4RAI50V and IL4RAQ576R) genes in conferring susceptibility to the development of atopy and/or asthma.Methods  Two polymorphisms in the IL-4 gene promoter, IL4-34CT and IL4-589CT, and two polymorphisms in the IL-4Rα chain gene, IL4RAI50V and IL4RAQ576R, have been genotyped using PCR-based methods in 341 asthmatic families and in 184 non-asthmatic adults recruited from the south of England.Results  Case–control analysis did not reveal differences in the distribution of the four polymorphisms between asthmatics and controls. However, the transmission disequilibrium test showed that the IL4-589 T allele was preferentially transmitted to asthmatic children (P=0.036) and that the IL4RAQ576 was preferentially transmitted to children with atopic asthma (P=0.018). Haplotype analysis showed a strong association between the IL4-34T/-589T haplotype and asthma per se (P=0.041), and a strong association between the IL4RA I50/Q576 haplotype and atopic asthma (P=0.006).Conclusion  Our data suggest that polymorphisms in the IL-4 and IL-4Rα chain genes might play a role both conferring susceptibility to and modulating severity of atopy and asthma.

Notes: Background 5-Lipoxygenase (5-LO) and 5-lipoxygenase-activating protein (FLAP) are essential for cysteinyl-leukotriene (cys-LT) production, critical mediators in asthma.Objective We sought to identify novel promoter polymorphisms within the FLAP (ALOX5AP) gene promoter and test the role of these and the previously identified 5-LO (ALOX5) Sp1 promoter polymorphism in asthma susceptibility.Methods To assess genetic association with asthma phenotypes, we genotyped 341 Caucasian families (containing two asthmatic siblings) and non-asthmatic control subjects (n=184). Genetic association was determined by case–control and transmission disequilibrium test (TDT) analyses. To determine the functional role of polymorphisms on basal transcription, we generated ALOX5AP-promoter-luciferase constructs and transiently transfected human HeLa cells.Results A novel G/A substitution at –336 bp and a poly(A) repeat (n=19 or 23) at position −169 to −146 bp were identified in the ALOX5AP promoter. Genotyping found the −336 A and poly(A19) alleles at frequencies of q=0.06 and 0.12, respectively. No ALOX5AP allele was associated with asthma or asthma-related phenotypes in case–control or TDT analyses. ALOX5AP-promoter-luciferase analyses did not support a functional role of the −336 or poly(A) polymorphism in determining basal transcription. The ALOX5 Sp1 polymorphism was predominantly homozygous wild-type 5/5 (frequency q=0.70) and heterozygous 4/5 (q=0.23) genotypes and no allele was associated with asthma or asthma-related phenotypes.Conclusion Taken together, these data do not support a significant role for these polymorphisms in genetic susceptibility to asthma in the Caucasian population.