2008; Dowlati et al. 2010; Duivis et al. 2013; Loftis et al. 2013a). Blockade of TNF-α is being evaluated both preclinically and clinically as a possible treatment for depression, and levels of TNF-α may also help predict antidepressant treatment response (Rethorst et al. 2013; Krügel et al. 2013; Raison et al. 2013). Here, TNF is linked to major depressive disorder.