Kenneth Anderson

Quantifying serum antibody in bird fanciers' hypersensitivity pneumonitis

BackgroundDetecting serum antibody against inhaled antigens is an important diagnostic adjunct for hypersensitivity pneumonitis (HP). We sought to validate a quantitative fluorimetric assay testing serum from bird fanciers.MethodsAntibody activity was assessed in bird fanciers and control subjects using various avian antigens and serological methods, and the titer was compared with symptoms of HP.ResultsIgG antibody against pigeon serum antigens, quantified by fluorimetry, provided a good discriminator of disease. Levels below 10 mg/L were insignificant, and increasing titers were associated with disease. The assay was unaffected by total IgG, autoantibodies and antibody to dietary hens egg antigens. Antigens from pigeon serum seem sufficient to recognize immune sensitivity to most common pet avian species. Decreasing antibody titers confirmed antigen avoidance.ConclusionIncreasing antibody titer reflected the likelihood of HP, and decreasing titers confirmed antigen avoidance. Quantifying antibody was rapid and the increased sensitivity will improve the rate of false-negative reporting and obviate the need for invasive diagnostic procedures. Automated fluorimetry provides a method for the international standardization of HP serology thereby improving quality control and improving its suitability as a diagnostic adjunct.

Randomised controlled trial of azithromycin in smokers with asthma

To the Editor: Smokers with asthma have poor symptom control, accelerated decline in lung function and an attenuated response to corticosteroids compared to nonsmokers with asthma [1]. There is an unmet need for alternative or additional drugs for smokers with asthma who are unable to stop smoking [2]. Macrolide antibiotics have anti-inflammatory activity [3] and in clinical studies there is good evidence for efficacy in the treatment of diffuse pan-bronchiolitis and cystic fibrosis, as well as in preventing chronic rejection after lung transplantation [4, 5]. In asthma, chronic treatment is associated with a reduction in bronchial hyperreactivity in mild-to-moderate asthma [6] and in exacerbation rates in non-eosinophilic severe asthma [7]. To date, no studies have examined the efficacy of macrolide antibiotics exclusively in current smokers with asthma. A randomised double-blind parallel-group trial compared azithromycin, 250 mg per day, with placebo for 12 weeks. All subjects were aged 18–70 years, were current smokers (≥5 pack-years history) with chronic asthma (>1 year duration; defined by international criteria [8]) and had to be free of exacerbation and respiratory tract infection for a minimum 6-week period prior to randomisation. A baseline visit was performed following a 4-week run-in period on inhaled corticosteroid (ICS) therapy equivalent to 400 μg beclometasone ± a long-acting β2-agonist (LABA). Ethical approval was obtained and all subjects provided written informed consent. Study visits were performed at 4, 8 and 12 weeks. Clinic visit peak expiratory flow (PEF) after 12 weeks treatment was the primary outcome measure. A sample size of 68 …

Extrinsic and intrinsic determinants of the host response in environmental lung disease

The development of lung disorders of environmental origin depends on a host response and the circumstances of exposure to noxious inhalable material. Climate, geography, culture, level of physical activity and the quality of indoor and outdoor air are important extrinsic variables. Host susceptibility is influenced by variable mechanisms which comprise plumonary defence. Few of these mechanisms are fully understood and most require more precise definition.