Survival and development of lymphomas in WT, Tg/+, and Tg/Tg mice. (A) Kaplan-Meier survival plot of overall survival of mice of the 3 genotypes. There is a statistically significant difference between survival curves (P = .041). Some mice were examined by necropsy when moribund. (B) Histologic and IHC features of spleens from Tg mice. (i) Low-grade splenic MZL showing enlarged MZ with atypical cells expanding into the red pulp (top left). Small follicular lymphocytes are at bottom right. (ii) Higher-grade MZL with centroblast-like cells both outside the marginal sinus (----) and in the follicle. (Inset) Same spleen stained with Ab to PAX5. (iii) High-grade MZL with the spleen almost totally occupied by cells with uniform features of centroblasts. (Inset) Same spleen stained with Ab to B220 emphasizes the almost total effacement of normal architecture by the aberrant B cells. (iv) Non-Tg spleen stained with Ab to human BCL10. (v) BCL10 Tg spleen with expanded MZ stained with Ab to human BCL10. (vi) Same spleen as in panel Bv, showing nuclear and cytoplasmic localization of BCL10. Histologic images were viewed with an Olympus Ax70 microscope (40×/0.75 oil objective lens) and photographed with an Olympus DP71 camera; DP controller software (Version 3.3.1.292) was used for image acquisition. (C) Southern blot hybridization analyses of Ig heavy chain gene organization in DNA prepared from spleens of 5 Tg/+ mice diagnosed with MZL. Locations of size markers and the germline (GL) band are shown on the left.