IL-1β and cleaved caspase-1 are found at high levels in human tissues of patients developing acute GvHD. (A) The presence of cleaved caspase-1 was determined in PBMCs from patients undergoing allo-HCT after stimulation with LPS (50 ng/ml) for 6 h. GvHD severity is indicated above the individual patient sample. (B) The amount of cleaved caspase-1 was determined by immunohistochemistry of intestinal biopsies derived from patients with or without GvHD. The cleaved caspase-1–positive cells were quantified by counting positive cells per high power field (HPF). (C) The amount of IL-1β was determined in freshly isolated PBMCs from healthy volunteers or patients undergoing allo-HCT and correlated with the incidence of acute GvHD. The left panel represents a representative flow cytometry plot; the diagram on the right shows the quantification for all individuals. Each data point represents an individual (n = 14–17 per group). (D) Immunohistochemical staining for IL-1β was performed on intestinal biopsies and correlated with the severity of acute GvHD. One representative sample is shown. (E) Immunohistochemical staining for IL-17A was performed on intestinal biopsies and correlated with the severity of acute GvHD. One representative sample is shown. **, P < 0.005; *, P < 0.05.