IL-1β expression and quantification in the lung. Immunohistochemical expression of IL-1β was detected using anti-IL-1β antibody in the lung sections from controls (A-B), one day (C-D) exposed rats without and with E. coli LPS challenge respectively, five day exposed rats without E. coli LPS challenge (E) and with E. coli LPS challenge (picture not shown). IL-1β expession in the airway epithelium (arrows, A-E) is shown. F. Quantification of IL-1β protein using ELISA shows increased concentrations in rats that received E. coli LPS compared to respective groups of rats that did not receive E. coli LPS (Figure 4, P < 0.001). Original magnification A-F: ×400 and micrometer bar = 50 μm.