Elevated interleukin-18 serum levels in chronic schizophrenia: Association with psychopathology

Background: Schizophrenia is associated with various abnormalities in the immune system including elevated levels of Interleukin-18 (IL-18), a potent inflammatory cytokine in T-helper 1 (Th1) responses. The aim of this study was to assess the clinical significance of serum IL-18 levels in various stages of schizophrenia. Methods: We measured serum IL-18 levels using a sandwich enzyme-linked immunosorbent assay (ELISA) from 78 never-medicated first-episode schizophrenia, 79 medicated chronic schizophrenia and 78 healthy control subjects. The symptoms of schizophrenia were assessed by the Positive and Negative Syndrome Scale (PANSS). Results: The chronic patients had significantly greater serum IL-18 levels than both first-episode patients and controls. Serum IL-18 was also positively correlated with the PANSS general psychopathology subscore in chronic schizophrenic patients. Conclusions: Our results showed elevated IL-18 pathway activity may be involved in the psychopathology of schizophrenia. (C) 2012 Elsevier Ltd. All rights reserved.