Cover: In situ phenotypic characterization of human mucosal APC subsets. Multicolor immunofluorscence staining for: (k) HLA-DR (green) or CD1c (k) (red), and laminin (g) RFD-7 (green) and CD14 (red); (h-j) Cd1c (red) and CD68, CD1a, or CD11c (green) in cryosections of normal nasal mucosa. (d-f) Paired immunostaining for HLA-DR (green) and CD68 (red) in whole-mount preparation of normal nasal mucosa; the image is a Z-projection of 18 superimposed optical sections (total depth 15 µm) from a field of lamina propria. A CD68-HLA-DR cell (f, arrow). (l-n) Paired immunostaining for CD11c (red) and CD2 (green) in cryosection of normal nasal mucosa. (m and n) Two consecutive optical sections (0.8-µm steps) of intraepithelial cells. (l) A superimposed image of five consecutive optical sections including m and n. Coexpression of markers is shown by yellow (some indicated by arrows). (g-i) Note similar distribution on epithelium and lamina propria of double positive cells for most markers except for less CD14+ cells in the epithelium (g) and lack of CD1a+ cells in the lamina propria (i). Broken line indicates the epithelial basement membrane and asterisk indicates the luminal side. Scale bars: g-k, 30µm; e, 15µm; and l, 10µm. For more information see article by Jahnsen and colleagues beginning on p. 31.