OBJECTIVETo study the expressions of CD55 and CD59 in patients with hyperlipidemia and the effects of atorvastatin on it, and to identify the possible influential factors.

METHODSWe selected 67 patients with hyperlipidemia, and 24 healthy people matched in terms of age, sex and body weight as control. The expressions of CD55 and CD59 on white blood cells were detected by flow cytometry, and their relationships to blood lipids, complement activation indexes (C(5a), sC(5b-9)), inflammatory factors (high sensitivity C-reactive protein (hsCRP), TNF-alpha, IL-6 were analyzed. 24 patients with hyperlipidemia were treated with atorvastatin for 8-12 weeks and the expressions of CD55 and CD59 were measured before and after atorvastatin therapy.

RESULTSThe mean fluorescence intensity (MFI) of CD55 lymphocytes and monocytes were decreased in patients with hyperlipidemia compared with control (2.07 +/- 0.28 vs 2.29 +/- 0.44 and 3.45 +/- 1.02 vs 4.33 +/- 2.32, P < 0.01 and P < 0.05, respectively). CD55 positive lymphocyte MFI was negatively correlated with waist circumference, waist-hip ratio, hsCRP and C(5a). C(5a) was negatively correlated with the MFIs of CD55 positive lymphocytes, monocytes, granulocytes, and positively with TG and diastolic blood pressure. After atorvastatin therapy, the MFIs of CD59 positive lymphocytes, monocytes and granulocytes increased (4.34 +/- 1.16 vs 3.69 +/- 0.76, 4.52 +/- 1.36 vs 3.91 +/- 0.89, 5.67 +/- 1.72 vs 4.56 +/- 1.03, P < 0.05, < 0.05 and < 0.01 respectively), which were not correlated with changes of blood lipids.

CONCLUSIONSThe expression of CD55 is down-regulated in hyperlipidemia, which might be influenced by obesity, abdominal distribution of adipose tissue and inflammatory status of hyperlipidemia, but not by blood lipids. The expression of CD55 is related with complement activation; The expression of CD59 is up-regulated after atorvastatin treatment independently of blood lipids.