Spontaneous inflammatory disease in Wdr1 mutant mice. (A) Hematoxylin and eosin–stained ear sections showing the epidermal hyperplasia and leukocytic infiltration characteristic of inflamed ears, with the cartilaginous scaffold of the ear indicated (black arrow). To illustrate the scale of the ongoing inflammatory process, wild-type and rd/rd images were taken at 200 × and 100 × magnification, respectively. (B) Peripheral blood neutrophil numbers are elevated in Wdr1^rd/rd mice compared with wild-type littermates. Individual male (■^+/+, □ rd/rd) and female (● ⁺/⁺, ○ rd/rd) mice are shown. (C) Anti-Gr1 immunohistochemistry on frozen sections of ear demonstrating the presence of large numbers of neutrophils within the lesion. (D) Anti-F4/80 immunohistochemistry demonstrating that macrophages are also present within the inflammatory lesion. Isotype controls for both Gr1 and F4/80 exhibited no staining (data not shown). (E,F) Peripheral blood platelet (E) and neutrophil (F) numbers in lethally irradiated recipients of wild-type or Wdr1^rd/rd bone marrow (■⁺/⁺, □ rd/rd). The CD45.1/CD45.2 leukocyte polymorphism system was used to distinguish donor from recipient hematopoiesis. Donor engraftment levels, as measured by contribution to peripheral blood leukocytes, were more than 90% in each recipient; n = 8 recipient mice per donor genotype. Data shown in (E,F) represent the mean plus or minus a standard deviation.