PDGFRA point mutations show increased lymphadenopathy compared with the FIP1L1-PDGFRA fusion in a syngeneic transplantation model. (A) H650Q and R748G are transforming in vivo. Kaplan-Meier plot shows survival of C3H/HeJ mice injected with 1.2 × 106 cells of 32D cell lines retrovirally expressing PDGFRA wt (n = 29), H650Q (n = 4), R748G (n = 15), and FIP1L1-PDGFRA (n = 5). (B) Diseased mice show significant enlargement of the spleen. Mice were killed on day 22 after injection for analysis. The numbers below the photographs depict spleen weight. (C-D) Lymph node and spleen weight of injected mice. Moribund or dead mice were analyzed for spleen and lymph node weight, controls were analyzed at various time points (range days 22-57; PDGFRA wt n = 17; H650Q n = 14; R748G n = 14; FIP1L1-PDGFRA n = 10). Included are untreated mice and mice treated with water by oral gavage. No statistical difference was observed between the 2 control groups (untreated vs water-treated) with the exception of R748G mice, because of 3 outliers which harbored greatly enlarged lymph nodes but marginally significantly smaller spleens. Statistical significance was tested with the nonparametric Mann-Whitney U test. (E) Hematopoietic and lymphatic organs show invasion of GFP-positive 32D cells. Bone marrow (BM), spleen (Spl), lymph nodes (LN), and peripheral blood cells (PB) were analyzed by flow cytometry for the presence of GFP-positive 32D cells. Depicted gates and percent values represent GFP-positive cells. Shown is 1 mouse of each group, analyzed 22 days after injection. (F) Histologic analysis of spleen, liver, and BM on day 22 after injection was performed after HE (hematoxylin/eosin) or NACE (Naphthyl acetate (chloro-)esterase) staining and showed infiltrates in the perivascular regions of the liver (arrows), a disturbed follicular structure of the spleen and remarkable reduction of NACE-positive cells in BM. Spleen and liver slides are depicted at ×10 magnification, BM at ×100.
