Pathomechanism of GVHD including neovascularization. APC, antigen-presenting cell; CTL, cytotoxic T lymphocyte; IFN, interferon; IL, interleukin; LPS, lipopolysaccharide; Mϕ, macrophage; Th1, T helper 1 cell; TNF, tumor necrosis factor. Modified and reprinted with permission from Elsevier (The Lancet, 2009, 373, 1550-1561).⁶