Splenic and renal histology. Sections showing ROS in NZB/W spleen tissue 2 hours after administration of (a) vehicle or (b) Bz-423 (×100). Increased staining was observed in b compared with a, demonstrating the ROS response. (c and d) Representative histology from 9.5-month-old mice, obtained after terminating longitudinal study. Spleen sections (×50) are shown from control (c) and Bz-423 (d) mice stained for B cells with anti-B220 (brown). (e and f) GCs (×400) from control (e) and Bz-423 (f) mice were identified by staining with Alexa 594–conjugated anti-B220 (red), and fragmented DNA (TUNEL, green) was detected by indirect immunofluorescence. GC B cells were distinguished by the intensity and location of the B220 staining relative to the splenic follicle architecture and confirmed by staining of serial sections with peanut agglutinin. (g and h) Kidney sections (×400) from control (g) and Bz-423 (h) mice stained with periodic acid-Schiff, showing representative glomeruli. (i and j) Kidney sections (×400) from control (i) and Bz-423 (j) mice, visualized with FITC-conjugated anti-Ig.