The autoimmune lymphoproliferative syndrome: an experiment of nature involving lymphocyte apoptosis.

Autoimmune lymphproliferative syndrome (ALPS) is a human disorder that has been characterized in the past two decades at both a functional and a genetic level. The underlying basis for this disorder is a defect in lymphocyte apoptosis that alters immune homeostasis resulting in an expansion of a normally rare circulating lymphocyte, the alpha beta double negative T cell. The abnormality in Fas mediated apoptosis underlying ALPS serves as a risk factor for autoimmunity involving blood cells and the development of lymphoma. There remain patients with a diagnosis of ALPS but without a defined genetic defect and current investigations are focusing on fully characterizing this patient subgroup.