Detection of complement activity by using a polysaccharide-protected membrane

The complement system of mammalian blood is a nonspecific part of the immune system involved in a number of disease conditions. We report the observation of pore creation caused by its activation in blood applied to the front gel layer of a bilayer membrane formed from dioleoylphosphatidyl choline and protected by a polysaccharide gel. The pores were detected by measuring the DC conductivity between nonblocking Ag/AgCl electrodes. The thickness of the protective gel was approximately 100 mu m, and the complement response was seen within 3 min after application of activator. The lifetime of such membranes is limited only by hydrolysis of the phospholipid constituting the membrane. This easily prepared system is suitable for examining the kinetics of complement component interactions with inhibitors. (C) 2000 Elsevier Science Inc. All rights reserved.