IL1B and depressive disorder: Specifically, we aimed to investigate first, how IL1β assays in plasma or lysates compare in their ability to discriminate between depressed MDD patients and controls, as well as between future responders and non-responders; second, whether depression severity correlates with plasma or lysate IL1β levels; and finally, we sought to assess whether longitudinal changes in IL1β concentrations derived from plasma or lysates would differ in their ability to reflect patients' response status.