Circulating levels of clusterin and complement factor H in patients with obstructive sleep apnea.

Obstructive sleep apnea (OSA) activates the complement system; however, the levels of membrane attack complex (MAC) are unaltered suggesting regulatory mechanisms. Our aim was to investigate complement factor H (CFH) and clusterin, two important complement regulators in OSA. We analyzed clusterin and CFH levels in plasma of 86 patients with OSA and 33 control subjects. There was no difference in CFH levels between patients (1099.4/784.6-1570.5/μg/ml) and controls (1051.4/652.0-1615.1/μg/ml, p = 0.72). Clusterin levels were higher in patients with OSA (309.7/217.2-763.2/μg/ml vs 276.1/131.0-424.3/μg/ml, p = 0.048) with a trend for a positive correlation with disease severity (p = 0.073). Increase in clusterin levels may be protective in OSA by blocking the MAC formation.