IL21 and graft versus host disease: While CpG-proBs had to be adoptively transferred during the initial phase of GVHD for protection, their effect on the T-cell cytokine profile was observed mostly on day+25, when the expression of CD4+ T-cell-derived cytokines involved in the inflammatory, humoral and fibrotic features of the chronic phase of GVHD, such as TNF-α, IL-21, TGF-β and IL-13, was significantly reduced in mLNs and pLNs of CpG-proB recipients compared to controls with GVHD.