<b><i>Background:</i></b> Schizophrenia is a disease of the nervous system, and immune system disorders can affect its pathogenesis. Activation of microglia, proinflammatory cytokines, disruption of the blood-brain barrier due to inflammation, activation of autoreactive B cells, and consequently the production of autoantibodies against system antigens are among the immune processes involved in neurological diseases. Interleukin-32 (IL-32) is a proinflammatory cytokine that is essential in activating innate and adaptive immune responses. This study aimed to measure the serum level of IL-32 as well as the frequency of autoantibody positivity against several nervous system antigens in patients with schizophrenia. <b><i>Material and Methods:</i></b> This study was conducted on 40 patients with schizophrenia and 40 healthy individuals in the control group. Serum IL-32 levels were measured by ELISA. The frequency of autoantibodies against Hu, Ri, Yo, Tr, CV2, amphiphysin, SOX1, Zic4, ITPR1, CARP, glutamic acid decarboxylase GAD, recoverin, titin, and ganglioside antigens was measured by the indirect immunofluorescence method. <b><i>Results:</i></b> Serum IL-32 levels in patients with schizophrenia were significantly higher compared to the control group. The frequency of autoantibodies against GAD and RI antigens in patients with schizophrenia was significantly higher than in the control group. Autoantibodies were positive in 8 patients for GAD antigen and 5 patients for RI antigen. Autoantibodies were also positive in 2 patients for CV2, 1 patient for Hu, and 1 patient for CARP. Negative results were reported for other antigens. <b><i>Conclusion:</i></b> Our findings suggest that elevated the serum IL-32 level and autoantibodies against GAD and RI antigens may be a reflection of immune system dysregulation in patients with schizophrenia.

Schizophrenia (SCZ) is a debilitating mental disorder with various causes involving complex interactions between genetic factors and environmental agents. The immune system plays a vital role in the pathology and function of the nervous system. Interleukin 35 (IL-35) is a regulatory and anti-inflammatory cytokine that can prevent autoimmune and inflammatory diseases. This study aimed to investigate the role of autoantibodies against some central nervous system (CNS) antigens and IL-35 serum levels in patients with Schizophrenia. This case-control study involved 80 participants. The serum levels of IL-35 were measured by enzyme-linked immunosorbent assay and the autoantibodies in the CNS by indirect immunofluorescence assay (IFA). The serum levels of IL-35 were decreased in patient groups compared to healthy subjects. Autoantibodies against N-methyl-D-aspartate receptor (NMDAR) and myelin-associated glycoprotein (MAG) were positive in 15% (6/40) and 7.5% (3/40), respectively; however, no antibodies against myelin, aquaporin-4 (AQP4), myelin oligodendrocyte glycoprotein (MOG), We found that decreased serum IL-35 levels and the existence autoantibodies against NMDAR antigen may contribute to the pathogenesis of SCZ.