Objective       To identify differentially expressed plasma proteins between euthymic bipolar disorder (BD) patients and healthy controls

and to find BD-associated proteins independent of mood episode.       Methods       Plasma samples from 12 euthymic BD patients and 20 healthy controls were immunodepleted of 7 high-abundance proteins

subjected to proteome-wide expression profiling by two-dimensional electrophoresis (2-DE)

and analyzed by MALDI-TOF/TOF. Proteomic results were validated by immunoblotting and analyzed with MetaCore software.       Results       2-DE analysi

s of euthymic BD patients and healthy controls found 45 differently expressed protein spots

and 27 mutually exclusive proteins were identified using MALDI-TOF/TOF. MetaCore analysis demonstrated that the functions of the altered proteins were mainly involved in immune response. The proteomic results of Apo A1 and A2M were validated by Western blotting and had significant difference (

P

<

0.05).       Conclusion       Differentially expressed proteins are found in plasma samples from euthymic BD patients compared to healthy controls

indicating that perturbations of lipid metabolism and immune response may be involved in the pathophysiology of BD.