KITLG and psychotic disorder: We examined serum levels of cytokines and growth factors, namely BDNF, chemokine (C-C motif) ligand (CCL)-2, CRP, IFN-γ, insulin-like growth factor binding protein (IGFBP2), IL-6, platelet-derived growth factor (PDGF), stem cell factor (SCF) and TNF-α in groups with different liability for psychosis, with and without the experiences of childhood trauma.