IL-27 Tg mice exhibit an increased number of megakaryocytes and splenomegaly with extramedullary hematopoiesis and shortened survival. (A) Spleen weight of wild-type (n = 31), IL-27 Tg no. 1 (n = 15) and no. 6 (n = 30) mice at 8 to 12 weeks of age was determined. Data are shown as the mean (± SD). * indicates P < .05, compared with wild-type mice. (B) Spleen, BM, and liver tissues of wild-type and IL-27 Tg no. 6 mice at 8 weeks of age were fixed in 10% buffered formalin, sectioned, stained with hematoxylin and eosin, and evaluated microscopically. (C) Survival rate of wild-type (n = 97), IL-27 Tg no. 1 (n = 51) and no. 6 (n = 46) mice was determined. (D) Spleen and BM tissues of wild-type and IL-27 Tg no. 1 mice at 40 weeks of age were fixed in 10% buffered formalin, sectioned, stained with hematoxylin and eosin, and evaluated microscopically. Images were acquired with an Olympus BX50 microscope system and 4×/0.13, 10×/0.30, and 20×/0.50 NA objectives (Olympus, Tokyo, Japan).