Alteration of Serum Levels of Cytokines in Schizophrenic Patients before and after Treatment with Risperidone

Abstract

A growing body of evidence suggests the existence of abnormalities in the immune system of schizophrenic patients. The current study examined serum levels of interleukin (IL) -1β, IL-6, IL-2,interferon(IFN) -γ, and tumor necrosis factor(TNF)-α in schizophrenic patients before and after treatment with risperidone and correlated levels of these cytokines with symptomatology. The study group consisted of 24 schizophrenic patients as defined by Diagnostic and Statistical Manual of Mental Disorders 4th edition (DSM-IV) criteria and 24 healthy controls. Serum cytokine levels were examined using enzyme-linked immunosorbent assay (ELISA). Schizophrenic symptomatology was assessed with the Positive and Negative Syndrome Scale (PANSS) questionnaire. The serum levels of TNF-α, IL-1β and IL-6 were significantly higher in participants before treatment compared with the healthy controls and after treatment (p<0.001). IFN-γ and IL-2 levels were significantly lower in participants after treatment compared with before treatment and the healthy controls (p<0.001). Except for IL-6 (p<0.05), there was no significant difference in the levels of TNF-α and IL-1β between the patients receiving treatment and the healthy subjects. Moreover, there was no significant difference in levels of IFN-γ and IL-2 between patients before treatment and the healthy subjects. There were no significant correlations between the concentration of cytokines studied and the PANSS. Positive intercorrelations between the production of IFN-γ and IL-2 were detected for sums of all groups(r=0.33, p=0.005). Clinical improvement of treated patients was associated with a reduction in the studied cytokines. It seems that changes in the cytokines level may play a significant role in the psychopathology of these patients.