Background: Dendritic cells (DC) are key regulators of the immune system, which is compromised in patients with bipolar disorder. We sought to study monocyte-derived DC in bipolar disorder. Methods: Monocytes purified from blood collected from DSM-IV bipolar disorder outpatients (n = 53, 12 without lithium treatment) and healthy individuals (n = 34) were differentiated into DC via standard granulocyte-macrophpage colony-stimulating factor/interleukin-4 culture (with/without 1, 5, and 10 mmol/L lithium chloride). The DC were analyzed for DC-specific and functional markers and for T-cell stimulatory potency. Results: Monocytes of bipolar patients showed a mild hampering in their differentiation into fully active DC, showing a weak residual expression of the monocyte marker CD14 and a relatively low potency to stimulate autologous T cells. Lithium treatment abolished this mild defect, and monocyte-derived DC of treated bipolar patients showed signs of activation (i.e., an up-regulated potency to stimulate autologous T cells and a higher expression of the DC-specific marker CD1a). This activated phenotype contrasted with the suppressed phenotype of monocyte-derived DC exposed to lithium in vitro (10 mmol/L) during culture. Conclusions: Dendritic cells show mild aberrancies in bipolar disorder that are fully restored to even activation after in vivo lithium treatment.

Bipolar disorder, Dendritic cells, Lithium, Monocytes,
Biological Psychiatry
Department of Immunology

Knijff, E.M, Ruwhof, C, de Wit, H.J, Kupka, R.W, Vonk, R, Akkerhuis, G.W, … Drexhage, H.A. (2006). Monocyte-derived dendritic cells in bipolar disorder. Biological Psychiatry, 59(4), 317–326. doi:10.1016/j.biopsych.2005.06.041