Specific uptake and transport of SIgA across murine and human FAE.

<p>(a) Mouse SIgA-Cy3 incubated for 60 min in a ligated intestinal loop containing a PP was taken up by M cells. Co-localization was observed with both UEA-1-FITC (a1) and GP2-FITC (a2) (<i>n</i> = 3). (b) Colocalization of SIgA-Cy3 with the Dectin-1 receptor stained in green with a specific mAb in the FAE overlying the PP (<i>n</i> = 2). (c) No entry of SIgA-Cy3 occurred in Dectin-1 KO mice (<i>n</i> = 2). (d–f) Images obtained from patient biopsy samples taken from the distal duodenum. V, villi. Biopsies were immunolabeled with human GFP-IgA2 and Dectin-1-PE (d) or Siglec-5-PE (e) at room temperature for 2 h. Conspicuous co-localization between GFP-IgA2 and Dectin-1-PE or Siglec-5-PE was observed (<i>n</i> = 2). (f) Negative controls were stained with secondary Abs alone (<i>n</i> = 2). On all pictures, dotted lines delineate the FAE separating the intestinal lumen and the lymphoid tissue (side view).