WASP and N-WASP-deficient B cells alter the MZ architecture. Immunohistochemistry of spleen sections from WT, WKO, and cDKO mice. (A) FO B cells were visualized with B220, MZ B cells with CD1d, and metallophilic macrophages with MOMA-1 Ab staining. MZ macrophages were visualized with SIGNR1 (B) and MARCO (C) Ab staining. (D) Quantification of MARCO⁺ cells from spleen sections shown in panel C. Each group represents quantification from 3 mice and 3 sections from each mouse. Note the marked reduction of FO B cells, MZ B cells, metallophilic macrophages, and MZ macrophages in cDKO mice. Original magnification was 10×. This experiment is representative of analysis of at least 3 WT, WKO, and cDKO mice.