IL6 and schizophrenia: Thus, the aim of the present study was to investigate the associations of proinflammatory cytokines, including IL-1β, IL-6, TNF-α, and IL-10, a suppressive cytokine, and brain-derived neurotrophic factor (BDNF) with the Kyn pathway, which might be related to the symptomatology of schizophrenia patients.