ABSTRACT
A) Etiology aGVHD is a consequence of donor T cells recognizing host antigens as for
eign. It results from an afferent phase of T lymphocyte stimulation (antigen presentation, T cell activation and T cell proliferation) and efferent phase of T cell and secondary effector cell response (cytokine secretion, cytotoxic T cells, natural killer cells). The essential factors necessary for aGVHD are: 1) immunologically competent donor T cells, 2) histoincompatibility between donor and host, 3) inability of host to reject donor lymphocytes.
