However, it is clear that the clinical manifestations of HLH are due to hyperactivation of CD8+ T lymphocytes and macrophages; proliferation, ectopic migration, and infiltration of these cells into various organs; hypercytokinemia with persistently elevated levels of multiple proinflammatory cytokines resulting in progressive organ dysfunction that may lead to death. The gene discussed is CD8A; the disease is hemophagocytic syndrome.