IL6 and bipolar disorder: In the study comparing serum levels of inflammation-related cytokines in bipolar patients during manic and depressive episodes, the authors showed a significant increase in IL6 levels during a depressive episode, but in mania, the IL6 level was under the sensitivity range of antibodies, suggesting different, phase-specific cytokine expression patterns in bipolar disorder (Ortiz-Domínguez et al. 2007).