Effect of blood microfilters on complement activity in human plasma.

While many devices that come into direct contact with patients' blood have been shown to be safe with respect to their effects on the cellular components and coagulation system of blood, many have not been examined with respect to their potential to activate the complement system. We present evidence that suggests that a combination of nylon plus polypropylene, and a combination of polyester plus polypropylene, found in blood microfilters used to protect patients from gaseous and particulate embolism during cardiopulmonary bypass, produce significant (p less than 0.01, p less than 0.05, respectively) C3a generation during incubation in heparinized plasma. Filter mesh composed of nylon plus polypropylene produced significantly more (p less than 0.01) C3a than the polyester plus polypropylene combination.