Hydrogen Peroxide Dismutation by Immunoglobulins G from Patients with Schizophrenia

The mechanisms underlying the recently discovered catalase activity of immunoglobulin G (IgG) in patients with schizophrenia remain unclear. Using a series of rigorous criteria, it has been demonstrated that this activity is an intrinsic property of antibodies themselves. The present study shows that classical catalase inhibitors also suppress the catalase activity of IgG. Specifically, inhibitor analysis revealed a dose-dependent reduction in the IgG catalase activity following addition of sodium azide (IC₅₀ = 140 μM) and 3-aminotriazole (IC₅₀ = 16.06 μM), suggesting that the catalytic mechanism of IgG shares similarities with that of classical catalase and may be due to the ability of antibodies to bind metalloporphyrin complexes, including heme. IgG catalase activity in patients with schizophrenia during therapeutic remission was significantly reduced, being fourfold lower than in healthy controls (p = 0.0004) and twofold lower than in patients during disease exacerbation (p = 0.002). A moderate positive correlation was observed between the total Positive and Negative Syndrome Scale (PANSS) score and IgG catalase activity (R = 0.32, p = 0.01). Therefore, IgG catalase activity in patients with schizophrenia depends on the disease clinical state and may contribute to the regulation of reactive oxygen species (ROS) metabolism and the severity of oxidative stress in affected individuals.