Isolation of late complement components by affinity chromatography. II. Purification of the human complement component C6.

We developed a new procedure for the rapid and gentle isolation of the human complement component C6 comparable to that described previously for C9. The procedure is based on affinity chromatography. As a first step, C6 is immunoabsorbed on insolubilized anti-C6 antibodies. These antibodies were derived from C6-defective rabbits (Freiburg strain). C6 was eluted with 3 M thiocyanate, pH 7.2, with a recovery of 15--23% of its hemolytic activity and a more than 270--fold purification. Impurities were removed in a second step by an "anti-impurity" column. The final product yielded a 12% recovery of the hemolytic activity and the purification factor was higher than 1300. The final product was homogeneous in SDS polyacrylamide and immunoelectrophoresis.