Objectives: To study the ex vivo interleukin (IL)-1β and IL-6 production of monocytes in bipolar disorder (BD) patients in the absence/presence of lithium.
Methods: Monocytes of outpatients with DSM-IV BD (n = 80, of whom 64 were lithium-treated) and of healthy control subjects (n = 59) were cultured in vitro and exposed (24 h) or not exposed to lipopolysaccharide (LPS) and/or graded concentrations of lithium chloride (LiCl). IL-1β and IL-6 production was assessed by enzyme-linked immunosorbent assay (ELISA) (supernatants).
Results: Monocytes stimulated by LPS from non-lithium-treated bipolar patients were characterized by an abnormal IL-1β/IL-6 production ratio, i.e., low IL-1β and high IL-6 production. Lithium treatment increased IL-1β and decreased IL-6 production and thus restored the aberrant ratio. In vitro exposure of monocytes to LiCl did not have the same effects as lithium treatment: the procedure decreased IL-1β production and had minimal effects on IL-6 production.
Conclusions: Blood monocytes have an altered proinflammatory status in BD. Lithium treatment restores this altered status. Short-term in vitro exposure of monocytes to lithium has other effects than lithium treatment.