Figure 4. SIgA modulates the acute inflammatory response to NTHi in vivo.
(a,b) Neutrophil and macrophage counts in BAL fluid from 2-month-old WT and pIgR−/− mice 24 h after aerosolization of NTHi lysate (10 mg). Six to eight mice per group; *P<0.01 compared with untreated mice (baseline), **P<0.01 compared with WT mice treated with NTHi (Student's t-test). (c) Dot-blot assay demonstrating protein binding between NTHi lysates and human SIgA from colostrum. (d) Immunofluorescent detection of human SIgA (green) in the lungs of pIgR−/− mouse 1 h after i.t. delivery of SIgA or vehicle (normal saline) (original magnification, × 200). Scale bar, 50 μm. (e,f) Parenchymal neutrophil and macrophage counts 24 h after aerosol delivery of NTHi lysate to 2-month-old pIgR−/− mice pretreated with i.t. SIgA (50 μl of 0.34 mg ml−1 solution) or vehicle (normal saline). Macrophage and neutrophil numbers were quantified by immunostaining for CD68 or NE, respectively. Five to six mice per group; *P<0.05 compared with mice pretreated with saline followed by NTHi (Student's t-test). (g) Western blotting and densitometry for p65 component of NF-κB (normalized to p84) in lung nuclear protein extracts from 2-month-old pIgR−/− mice pretreated with i.t. SIgA or normal saline 1 h before NTHi nebulization and harvested 24 h later. Six mice per group; *P<0.05 (Student's t-test).