Cell cycle progression of pro-T cells and pre-T cells is impaired during GVHD.

Acute (C) or chronic (D) GVHD was induced in unirradiated B6D2F₁ mice. Untransplanted (A) or syngeneically transplanted (B) B6D2F₁ mice served as controls. TN thymocytes were analyzed at 2 weeks after transplantation for the surface expression of CD44 and CD25 and for the incorporation of BrdU into cellular DNA. Numbers depicted in each quadrant of the dot plot represent mean frequencies (%) of the respective populations. (E, F) Frequencies (%; mean ± SEM) and absolute cell numbers (×10⁻³) of cycling cells among TN thymocytes was assessed by flow cytometry of thymuses from untransplanted (▨) or syngeneically transplanted (□) B6D2F₁mice and from mice with acute (▪) and chronic () GVHD, respectively. The graph represents pooled data from 2 independent experiments; 3 to 5 mice were analyzed for each group.^*P < .01 versus mice with chronic GVHD and syngeneic controls, respectively. ^†P < .02 versus syngeneic controls (ANOVA).