CX3CR1 is expressed in human airway epithelial cells and is localized to the motile cilia.

<p>HAE cells were grown in an air-liquid interface (ALI) culture system until differentiation was achieved, and imaged by confocal immunofluorescence. (<b>a</b>) Anti-β-tubulin (green) and anti-CX3CR1 (red) immunodetection of the cells seen <i>en face</i> are shown individually and merged (scale bar 10 μm). An xz plane image (XZ Merge) further illustrates the localization of CX3CR1 in motile cilia (scale bar 5 μm). Nuclei, stained with DAPI, are rendered in blue. (<b>b</b>) Immunostaining with isotype control antibodies confirms the specificity of the immunostaining. The merge image and XZ merge image are in planes that cross nuclei to confirm the presence of cells and the absence of non-specific immunostaining. (<b>c</b>) Confocal immunofluorescence images of differentiated HAE cells. Cells were either infected with RSV strain MSA1 (top and bottom rows), or mock infected (middle row). Images were acquired either two hours (left two columns), 1 day (middle two columns), or 3 days (right two columns) after infection or mock infection. CX3CR1 immunofluorescence is shown in (purple) (top two rows), or using an isotype negative control (bottom row). The cells were also stained for nuclei using DAPI (blue). Two representative images are shown for each condition tested. The 2-hour time point images are of an xy plane above the nuclei, intersecting the motile cilia. CX3CR1 immunofluorescence is clearly detected in the cilia of both infected and uninfected cells but is absent in the isotype control samples. The 1-day and 3-day time points are in an xy plane crossing the nuclei, 4.3 μm below the motile cilia.