Analysis of peripheral immune activation in schizophrenia using quantitative reverse-transcription polymerase chain reaction (RT-PCR).

Immune system abnormalities in schizophrenia include a shift from a Type 1 (cellular) to a Type 2 (humoral) immune response. To characterize the activation status of the immune system in schizophrenia, we examined the pattern of gene expression in peripheral blood cells for three Th1 cytokines (interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), interleukin-2 (IL-2)), and one Th2 cytokine (interleukin-10 (IL-10)). In a cross-sectional study, we used quantitative reverse-transcription polymerase chain reaction (RT-PCR) to compare the mRNA levels of IFN-gamma, TNF-alpha, IL-2, and IL-10 in peripheral blood mononuclear cells (PBMCs) between 15 schizophrenia patients and 15 matched healthy controls. Expression of IFN-gamma and TNF-alpha was significantly reduced in patients with schizophrenia compared with normal controls. No differences in IL-2 and IL-10 gene expression were observed. These results are consistent with impaired Type 1 cellular immunity in schizophrenia. While the data illustrate the potential utility of mRNA-based approaches for the identification and analysis of immune biomarkers for neuropsychiatric disorders, correlation of gene expression with direct measures of cytokine concentrations is required. Copyright (c) 2008 Elsevier Ireland Ltd. All rights reserved.