Immunohistochemistry.
Paraffin-embedded spleen sections were deparaffinized in Histoclear (National Diagnostics) and rehydrated in graded ethanol. Sections were antigen retrieved by microwaving in citrate buffer (pH 6.0) for 15 min (LMP1 staining) and 10 min (pStat3 staining). For LMP1 staining, sections were blocked with 1% BSA and 0.1% cold fish skin gelatin followed with streptavidin/biotin block (Vector Labs). Rat IgG anti-LMP1 (clones 8G3 and 1G6, Ascenion) were used at 1:10 dilution from tissue culture supernatants, followed with 8 mug/ml biotinylated mouse F(ab') anti-rat IgG (H+L) pre-adsorbed to mouse serum (Jackson ImmunoResearch) and 2 mug/ml streptavidin-alkaline phosphatase conjugate (Jackson ImmunoResearch). Stains were developed with BCIP/NBT and counterstained in Nuclear Fast Red (Dako). Phospho-Stat3 was detected with 4 mug/ml of pStat3 antibody (Tyr705, Cell Signaling) and detected with anti-rabbit Poly-HRP IHC detection kit (Chemicon). 
