In the light of studies reporting that serum levels of IFN-γ and in vitro IFN-γ production after stimulation were lower in samples obtained from unmedicated schizophrenia patients vs. healthy controls (173, 174), a pilot study was undetaken in two treatment-resistant schizophrenia patients in which IFN-γ-1b was administered subcutaneously and psychopathology was assessed weekly with the PANSS (175). This evidence concerns the gene IFNG and schizophrenia.