Fig. 5

In vitro quantitation by ELISA tests of polymeric immunoglobulin receptor (pIgR) (secretory component) in the supernatants and cell lysate of normal primary human bronchial epithelial cells (16HBE) treated with lipopolysaccharide (LPS, 10 μg/ml), hydrogen peroxide (H₂O₂, 100 μM) and IL-8, 10 ng/ml). In the supernatant, LPS stimulation significantly increased pIgR protein release at 4 and 24 h after stimulation (a). IL-8 stimulation significantly increased pIgR protein release at 4 h, followed by a decrease at 12 and 24 h (c). Stimulation by H₂O₂ significantly decreased pIgR release at 12 h (b). In the cell lysate, LPS had no effect on pIgR expression at any time point or concentration studied (d). IL-8 stimulation significantly increased pIgR expression at 4 h after treatment (f). H₂O₂ significantly reduced pIgR concentrations at 4 h after treatment in the cell lysates of 16HBE cells (e)