Serum interleukin-18 levels are elevated in schizophrenia

Interleukin-18 (IL-18) is a recently discovered proinflammatory cytokine wh ich plays a pivotal role in T helper 1 (Th1) responses. IL-18 is produced b y macrophage-like cells, and inappropriate IL-18 production has been known to be involved in immunological disturbances. Schizophrenia is a common dis ease whose pathogenesis is still unclear; however, an activation of the inf lammatory response system, including the Th1 cytokine response, may be rela ted to the pathophysiology of schizophrenia. We measured the serum IL-18 le vels of 66 schizophrenics and age- and sex-matched control subjects by usin g an ELISA assay. We found significantly increased serum IL-18 levels in th e schizophrenic patients (P = 0.0002). This finding supports the hypothesis that immune activation is involved in the pathophysiology of schizophrenia . (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.