WASp-null CD11c⁺ DCs are able to redistribute from red pulp and the marginal zone of the white pulp to the T-cell zone after challenge with STAg or LPS, although some DCs remain in the marginal zone. Spleens from control sv129 (WT) and WASp-null mice were challenged with PBS, STAg, and LPS and analyzed 6 hours after injection. The sections were stained for CD11c (brown) and CD19 (pink) to delineate the follicles in the white pulp and analyzed. (A) The splenic microarchitecture in the WASp-null mice (bottom row) was observed to be somewhat disfigured compared with control mice (top row). At low power, “nests” of DCs in T-cell areas are clearly visible in both mice (scale bar represents 400 μm). (B) Higher-power images indicate the presence of CD11c⁺ cells exclusively in T-cell areas (arrow) in normal spleen (top row) after challenge with STAg or LPS. However, in WASp-null spleen (bottom row) a proportion of CD11c⁺ cells is retained in the marginal zone (highlighted in boxed areas) (scale bar represents 200 μm). The STAg challenge data shown are representative of 3 experiments, and LPS challenge data represent 1 experiment with triplicate samples.