Background and Objectives: There is no
biomarker to predict
lithium response. This study used CellPrint™ enhanced flow cytometry to study 28
proteins representing a spectrum of cellular pathways in monocytes and CD4+ lymphocytes before and after
lithium treatment in patients with
bipolar disorder (BD). Materials and Methods: Symptomatic patients with BD type I or II received
lithium (serum level ≥ 0.6 mEq/L) for 16 weeks. Patients were assessed with standard rating scales and divided into two groups, responders (≥50% improvement from baseline) and non-responders. Twenty-eight intracellular
proteins in CD4+ lymphocytes and monocytes were analyzed with CellPrint™, an enhanced flow cytometry procedure. Data were analyzed for differences in
protein expression levels. Results: The intent-to-treat sample included 13
lithium-responders (12 blood samples before treatment and 9
after treatment) and 11
lithium-non-responders (11 blood samples before treatment and 4
after treatment). No significant differences in expression between the groups was observed prior to
lithium treatment.
After treatment, the majority of analytes increased expression in responders and decreased expression in non-responders. Significant increases were seen for PDEB4 and NR3C1 in responders. A significant decrease was seen for NR3C1 in non-responders. Conclusions:
Lithium induced divergent directionality of
protein expression depending on the whether the patient was a responder or non-responder, elucidating molecular characteristics of
lithium responsiveness. A subsequent study with a larger sample size is warranted.