Spleen and BM aplasia in IFN-γRKO hosts. (A) Picture showing the spleen of a normal B6 mouse and the spleens of wt and IFN-γRKO recipients on day 15 after transplantation. (B) Histologic scoring (0-4) of spleen GVHD based on criteria displayed in Supplemental Table S1 (3 mice per group). (C) Spleen cellularity at 3 time points (days 4, 8, and 15), in wt, IFN-γRKO as well as in syngeneic (C3H.SW) hosts. (D) Numbers of CD8⁺, CD4⁺, CD11b⁺, and CD19⁺ cells in the spleen of wt and IFN-γRKO recipients on day 15. (B-D) Histograms represent the mean and SD of at least 3 mice per group from 3 distinct experiments. (E) IFN-γ levels in BM supernatants harvested on days 4 (d4) and 8 (d8) after transplantation. (F) BM cellularity on day 15 after transplantation in syngeneic and allogeneic recipients. Absolute number of cells per BM sample obtained from 1 tibia and 1 femur. (G) Absolute numbers of donor Lin⁺ and LSK cells in wt and IFN-γRKO hosts. (E-G) Histograms represent the mean and SD of at least 3 mice per group from 1 representative experiment out of 2. Statistically significant differences between wt and IFN-γRKO hosts are shown. *P < .05, **P < .01, ***P < .001.