Immunohistochemical staining of MnSOD protein in normal human lymphoid tissues and DLBCL patient samples. The top row of photomicrographs shows immunohistochemical staining for MnSOD protein (brown) in normal spleen, lymph node, and a reactive lymph node (antigen stimulated). The bottom row shows staining in 2 different patient samples selected to represent, from left to right, low and high MnSOD staining. These images are from different tissue samples on the same tissue array slide (original magnification, × 400). The third panel (far right) in the bottom row is a higher magnification (original magnification, × 1000) view of the high MnSOD-staining tumor sample shown in the middle panel of the bottom row. The large atypical cells clearly show a cytoplasmic staining pattern. Images were viewed on a Nikon Labphot 2 microscope using 40×/0.65 and 100×/1.25 oil-immersion objective lenses (Nikon, Melville, NY). Images were acquired with a SPOT RT Color 2.2.0 camera (Diagnostic Instruments, Sterling Heights, MI) and Spot Advanced 4.0.9 software for Windows. Cover slips were mounted on the slides using Pro-Texx Mounting Medium (VWR International, West Chester, PA).