STAT5B^N642H induces transplantable NK-cell leukemia in mice. (A) Schematic overview of the IV transplantation of splenocytes from diseased N642H^NK/NK mice into NSG mice. (B) Survival analysis of NSG mice that received transplantation with splenocytes of diseased N642H^NK/NK mice (numbers 1-4 and 6-8) (n = 7). (C) Quantification of body weight (left), spleen to body weight ratio (middle), and liver to body weight ratio (right) of diseased NSG mice with N642H^NK/NK transplantation and untransplanted controls (n ≥ 4 per group; mean ± standard deviation). (D) Flow cytometric analysis of GFP⁺ cells in different tissues of NSG mice that received transplantation with splenocytes from the different diseased N642H^NK/NK mice (first transplant). (E) Quantification of the leukemia type developed by NSG recipients of diseased N642H^NK/NK splenocytes. (F) Representative images of hematoxylin and eosin stained blood smears from NSG mice that received transplantation with splenocytes from diseased N642H^NK/NK mouse number 7 (left) and number 3 (right). (G) Schematic overview of the IV transplantation of splenocytes from diseased NSG mice with N642H^NK/NK transplantation into another round of NSG recipients or immunocompetent WT (Ly5.1⁺) mice (second transplant). (H) Survival analysis of NSG and Ly5.1 recipients with N642H^NK/NK transplantation (n = 4 per group). Levels of significance were calculated using the unpaired t test (C). ∗P < .05; ∗∗P < .01. WT, wild type.