Day 2 at the reduction stage of acute respiratory illness. (A) Comparative analysis of the acute respiratory illness-associated genes of D2 with respect to D6 indicated a core of n = 33 genes across all study groups (box). Complete gene lists generated for each comparison are outlined in Table S1 in Additional file 2. (B) Hierarchical clustering analysis of the D6 versus D2 microarray expression of the core-D2 genes. (C) Quantitative real-time PCR confirmation of select core-D2 gene expression. Horizontal line depicts mean. Number of matched D2 and D6 samples from each group used for quantitative real-time PCR assays are indicated below. (D) Influence of medication use on core-D2 gene expression for all asthmatics. Horizontal line depicts mean. CXCL11/9, Chemokine (C-X-C motif) ligands; CCL2, Chemokine (C-C motif) ligand; D2, day 2; D6, day 6; GCN, fold change in normalized gene copy number; ICS, inhaled corticosteroids; NS, nasal steroids.