TNF and schizophrenia: Meta-analyses of 40 studies suggests that interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor growth factor- β (TGF-β) are cytokines associated with acute symptom exacerbation whereas TNF-α, interleukin-12 (IL-12), interferon- γ (IFN-γ), and soluble IL-2 receptor (sIL-2R) levels appear to remain stable in schizophrenia (Miller et al., 2011).