Oxidative stress as a potential causal factor for autoimmune hemolytic anemia and systemic lupus erythematosus

Figure 1 Oxidative stress and antioxidative/redox systems in red blood cells. A part of oxygenized hemoglobin (Hb-O₂) is autoxidized to methemoglobin (MetHb) and releases superoxide (O₂^-.), which may cause oxidative damage to RBCs. MetHb can be reduced back to Hb by methemoglobin reductase in NADPH-dependent manner. G6PD, a rate-determining enzyme in the pentose phosphate pathway, is involved in the production of NADPH that supports antioxid/redox systems as well as methemoglobin reduction by donating redox potential. G6PD deficiency affects entire antioxidative/redox systems, which can consequently accelerate the destruction of RBCs and lead to anemia. RBCs: Red blood cells. NADPH: Triphosphopyridine nucleotide.