All components of the immune system, i.e. autoantibodies, cytokines, the complement system, phagocytes, B and T lymphocytes including cytotoxic CD8 + T cells and CD4 + T regulatory cells (Tregs), and NK cells are important players in the pathogenesis of AIHA, and all change with age. The gene discussed is CD4; the disease is autoimmune hemolytic anemia.