Characterization of the isolated primary nasal cells at different digestion times. A Double immunofluorescence staining of CD163 (red) in combination with Sn or vimentin or cytokeratin (green) in cells isolated after 24 h, 48 h, and 72 h digestion. CD163+ macrophages of various sizes are indicated with different arrows; yellow arrows (~25 µm), cyan arrows (~16 µm), and white arrows (~10 µm). Scale bar: 25 µm. B Percentage of positive cells from each time point are presented. Statistical significance was determined by two-way ANOVA followed by Tukey’s post hoc test (*p < 0.05, **p < 0.01). All data are expressed as mean value of three experiments ± SD. C Flow cytometric analysis of the primary nasal cells collected after 72 h digestion.