IL6 and major depressive disorder: Taken together, our findings support the notion that CBT influences peripheral IL-6 in individuals with depression and represents a point of commonality with other antidepressant treatment modalities (e.g., antidepressants).<h4>Systematic review registration</h4>https://doi.org/10.17605/osf.io/tr9yh, identifier: 10.17605/osf.io/tr9yh.