IL6R and graft versus host disease: Among the transplanted mice, the half-life was shorter in recipients of Cd4Cre–Il6rfl/fl grafts as compared with recipients of Il6r–/– (Cre+) grafts (t1/2 1.6 days vs. 2.1 days), and the difference was maintained even when GVHD was attenuated by the administration of cyclosporine A (CSA) (t1/2 1.7 days) (Figure 3G and Supplemental Figure 3A), a standard GVHD prophylaxis agent in clinical BMT.