Lymphoma development in IgH^P5ki mutant mice. (A) Kaplan-Meier survival curves. The survival of IgH^P5ki/+ mice (n = 153) and IgH^P5ki/P5ki mice (n = 46) was followed over time. Lymphomas were detected in all dead IgH^P5ki/P5ki mice, which were subjected to macroscopic or histologic analysis. Because we were unable to analyze 36% of the IgH^P5ki/P5ki mice at death, we conclude that at least 64% of all homozygous mutant mice died due to lymphoma development. (B-D) Gross aspect of the thymus (B), spleen (C), and lymph nodes (D) of the moribund IgH^P5ki/P5ki (ki/ki) tumor mouse 11 and a wild-type (+/+) littermate. (E-G) Disrupted architecture of the thymus in the IgH^P5ki/P5ki tumor mouse 11. Histologic sections of the thymus from a wild-type mouse (E) and the IgH^P5ki/P5ki tumor mouse (F-G) were stained with eosin and hematoxylin. The cytologic details of the tumor cells are shown at higher magnification in panel G. CO indicates cortex; ME, medulla. (H-K) Infiltration of the lung (H), liver (I), and kidney (J) by lymphoma cells in the diseased IgH^P5ki/P5ki tumor mouse 11.