A general method for affinity purification of complement component C3b using factor H-sepharose.

Complement component C3b has been purified from human, rabbit and bovine serum by affinity chromatography on human factor H-Sepharose after preliminary fractionation by poly(ethylene glycol) and DEAE-Sepharose. The yields are high (35--40%) and the whole process is rapid (3 days). Binding of C3b to factor H-Sepharose is equimolar, has a sharp optimum pH at 7.6 and is quite sensitive to ionic strength.