Investigation of serum cytokine levels and cytokine production in whole blood cultures of paranoid schizophrenic patients

There is some evidence that the pathophysiology of schizophrenia is related to changes in the innate and adaptive immune systems. In an attempt to define a potential immunological dysfunction in schizophrenia, we measured the serum levels of several cytokines in the sera of 24 patients with paranoid schizophrenia and investigated the cytokine production in whole blood assays after stimulation in vitro with virus (Newcastle d isease), phytohemagglutinin (PHA) or bacterial lipopolysaccharide (LPS) and compared them with healthy, normal controls. A significant increase of interleukin 6 (IL-6), IL-8 and interferon γ (IFN-γ) levels, but a de- c reased IL-10 level were observed in the sera of patients with schizophrenia. No significant changes in the serum l evels of IL-2, IL-4, IFN-α and tumor necrosis factor α (TNF-α) were detected in these patients. When cytokine p roduction in vitro was examined, a significant defect in PHA-induced IL-2, IL-4 and IFN-γ , and in virus-induced IFN-α production, but no significant alterations in LPS-induced IL-6, IL-10 and TNF-α production were observed. In summary, increased serum levels of some cytokines such as IL-6, IL-8 and IFN-γ indicate an activation of the inflammatory response i n schizophrenia, while the in vitro assay indicates significant changes in the Th1 (decreased production of IL-2 and IFN-γ ) and Th2 (decreased production of IL-4) cell system responses. The role of the defective IFN -α production in the r egulation of the imbalance between Th1 and Th2 cell system responses is suggested.