With these efforts, we can continuously monitor the dynamic change of immune status (not only plasma IFN-γ, IL-4, Il-10, IL-12 levels, but also the Th1, and Th2 frequencies within total CD4+ T cells simultaneously) and then to establish the relationship between kinetics of immune status and the clinical activity of both acute and chronic GVHD. This evidence concerns the gene IL4 and chronic graft versus host disease.