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.