C4B and depressive disorder: Although the serum HDL-CH value in patients was not significantly different from the serum value of HDL-CH in healthy controls, a negative correlation of HDL-CH with CDI score and of non-atherogenic L-HDL-3 subfraction with a CDI score as well as a positive correlation of supposedly atherogenic I-HDL6 subfraction with CDI before omega-3 FA supplementation points to a hypothesis of a potential role of HDL subfractions in the pathophysiology of depressive disorder.