Schematic of the experimental approach to blood donor characteristics, matching, monocyte and MDMs culture, and stimulation conditions. A peripheral blood sample was simultaneously obtained from age-and race-matched subjects in pairs, one female and one male, either healthy or asthmatic between 8:00 AM and 10:00 AM on day 21 of the menstrual cycle of each female subject. Blood mononuclear cells (PBMC) were isolated by gradient separation and monocytes were enriched by adhesion. Serum from each subject was collected for monocyte-to-MDM culture after heat inactivation (autologous serum). Enriched monocytes were either stimulated with IL-4 or IL-13 for 24 h prior to mRNA collection or cultured in 10% autologous serum and 25 ng/mL of rmM-CSF for 7 days (monocyte-to-MDM culture), MDMs were stimulated with IL-4 or IL-13 for 24 h followed by mRNA collection.