Cellular immunity impaired in schizophrenia
MedWire News: Patients with schizophrenia show a significant reduction in interferon (IFN)-γ and tumor necrosis factor (TNF)-α gene expression compared with mentally healthy controls, indicative of compromised Type 1 cellular immunity, research shows.
The finding is consistent with the hypothesis that immune activation plays a role in the pathogenesis of some symptoms of schizophrenia, say Oliver Freudenreich (Massachusetts General Hospital, Boston, USA) and colleagues in the journal Psychiatry Research.
The researchers explain that an intact Type 1 response is necessary for the control of many viral and intracellular parasitic infections. Impaired Type 1 immune responses could in theory cause neurologic damage through certain infections, both in utero and later in life. Toxoplasma gondii serum antibodies in schizophrenia patients compared with controls.
Support for the role of a dysregulated immune system in schizophrenia also comes from trials of anti-inflammatory agents, which have been reported to have therapeutic benefit.
To investigate further, the researchers took peripheral blood samples from 15 patients with schizophrenia and 15 age- and gender-matched mentally healthy controls. They used quantitative reverse-transcription polymerase chain reaction to measure the messenger(m)RNA expression of four cytokines involved in modulation of cellular immunity: IFN-γ, TNF-α, interleukin (IL)-2, and IL-10.
The researchers report that there was a significant 25-fold reduction in expression of IFN-γ in patients with schizophrenia compared with mentally healthy controls.
There was also a modest but significant two-fold reduction in TNF-α expression in patients with schizophrenia compared with controls.
By contrast there was no difference in IL-2 or IL-10 expression between the groups, suggesting that Type 2 (humoral) immunity is probably preserved in schizophrenia, say the researchers.
“This study highlights the feasibility of using mRNA expression analysis in peripheral blood cells as a means to characterize the activation state of the immune system in schizophrenia and other mental illnesses,” Freudenreich et al comment.
“Impaired cellular immunity regardless of etiology would have functional relevance for the control of infections in schizophrenia.”
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By Andrew Czyzewski