Figure 1: Presence of P. acnes in mouse prostate-infiltrating macrophages. (a) Inflamed dorsal prostate gland 2 weeks after infection with P. acnes. Glandular lumen contains primarily macrophages as indicated by IHC for F4/80 macrophage marker. (b) Adjacent section stained with an anti-P. acnes antibody. Note dense accumulation of P. acnes cells in macrophages within glandular lumen. (c) Enlarged view of boxed area in (b). Single P. acnes cells can be visualized within prostate-infiltrating macrophages (arrow). (d) Additional image of P. acnes cells (arrows) in prostate-infiltrating macrophage as indicated by IHC with anti-P. acnes antibody.