FAS and chronic graft versus host disease: While CD27 and Fas were initially elevated in both oGVHD patients (molecules which were undetectable in control subjects), TRAIL-R2 was only detectable in the acute oGVHD case (and not in the chronic GVHD patient, nor in the investigated control subjects), with TRAIL being initially reduced in the acute oGVHD case when compared to the chronic oGVHD case or controls.