High levels of peripheral IL-6, a pro-inflammatory cytokine, have been indicated as a key element of the bipolar disorder (BD) (Lu et al., 2019a), allowing to differentiate BD from major depression with high accuracy (Poletti et al., 2020) and to early detect poor responders to antidepressant treatments (Benedetti et al., 2017). Here, IL6 is linked to Behcet disease.