Post-hematopoietic stem cell transplantion immune-mediated cytopenias

摘要

Immune dysregulation is a common consequence following allogeneic stem cell transplantation (SCT). In addition to the well-known immuno-logical reactions of graft-versus-host (GVH) and host-versus-graft reactivity, resulting in GVH disease (GVHD) and graft rejection, respectively, the development of multiple autoimmune phenomena such as thyroiditis or myasthenia gravis has been reported [1,2]. Although cases of passive transfer of donor autoimmunity, such as myasthenia gravis [3], diabetes mellitus [4], hyper-thyroidism [5] and autoimmune thrombocy-topenic purpura [6], have been well documented, it seems that the vast majority of autoimmune-mediated disorders are the direct consequence of the severe post-transplant immune dysfunction [7]. In fact, many of the manifestations of chronic GVHD are mimicking autoimmune diseases such as scleroderma or primary biliary cirrhosis, and it is not surprising that many of the observed autoimmune phenomena are associated with it [8]. In general, the pathogenesis of autoimmunity is multifactorial and includes genetic, infectious and possibly environmental factors. Although the same factors can play a role in autoimmunity following allogeneic SCT, dysfunction of central and peripheral tolerance mechanisms seem to be the most significant contributors. Thymic damage due to age, prior chemoradiotherapy or GVHD can lead to impaired negative selection and to the emergence of autoreactive T-cell clones [9,10].