PAF and PAF-like oxidized phospholipids hydrolysed by platelet-activating factor 
(PAF) acetylhydrolase (AH) are potent lipid mediators involved in inflammation 
and atherosclerosis. Apolipoprotein (apo) E-containing high-density lipoprotein 
(HDL) has antioxidant, anti-inflammatory and anti-atherogenic properties. The 
study investigated apoE-containing HDL-associated PAF-AH (HDL-PAF-AH) and total 
(apoE-containing+apoE-poor) HDL-PAF-AH activities as well as malondialdehyde 
(MDA) concentration in 291 patients with polycystic ovary syndrome (PCOS) using 
the Rotterdam consensus criteria and 281 control women. Compared with the 
control women, patients with hyperandrogenism+oligo/anovulation+polycystic 
ovaries (PCO) or hyperandrogenism+PCO had lower total, apoE-containing and 
apoE-poor HDL-PAF-AH activities, while those with oligo/anovulation+PCO showed 
decreased total and apoE-poor HDL-PAF-AH activities. Other factors including 
insulin resistance and obesity in PCOS had the adverse effects associated with 
the HDL-PAF-AH activities. Serum MDA concentration was associated with PCOS, 
hyperandrogenism, insulin resistance and hypertriglyceridaemia in patients with 
PCOS. Decreased total and apoE-containing HDL-PAF-AH activities and increased 
serum MDA concentration may contribute to the pathogenesis of PCOS and 
potentially link to related complications responsible for oxidative stress and 
inflammation such as an increased risk for type 2 diabetes mellitus and/or 
future cardiovascular diseases in PCOS patients.