Allergic asthmatic, allergy only, asthma only (no allergy), and non-allergic non-asthmatic (control) subjects underwent bronchoscopy with instillation of saline, lipopolysaccharide (LPS), and house dust mite antigen in separate subsegmental bronchi. Bronchoalveolar lavage (BAL) fluid was collected four hours later (three samples per subject). Inflammatory cells from each specimen were isolated and RNA was extracted for microarray analysis. Keywords: gene expression arrays (two-dye: sample against common 'universal' reference RNA)
Overall design
There are four main phenotypic groups: 1. control (no allergy or asthma) 2. allergy only (no asthma) 3. asthma only (no allergy) 4. allergy and asthma and three exposures: saline, house dust mite antigen (HDM), and LPS.
Samples from the different exposures were all collected at the same time: four hours after instillation. The hybridizations were carried out in two main 'batches': samples in batch 1 were processed in mid 2004, samples in batch 2 about a year later in 2005. There is a clear 'batch effect': differences between expression profiles from the two batches (likely caused by technical differences between hybridization and scanning methods). This should be considered when analyzing the data.
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