[Effective method of simultaneous isolation from human serum of highly purified factors B and D of the alternative pathway of complement activation].

A simple method for isolation from human serum of the complement alternative pathway factor B, in a yield over 40% and purity over 80% with respect to protein, has been developed. Such a high yield was reached due to rejection of ammonium sulphate fractionation and employment of only two chromatographic stages: on CM-Sephadex C-50 and on DEAE-Sepharose CL-6B. An additional chromatography on QAE-Sephadex A-50 provides factor B of 100% purity but with a loss of some amount of protein (yield approximately 20%). One of the fractions, obtained at the first stage of factor B purification, contained also factor D. After rechromatography on CM-Sephadex C-50 and gel filtration on Sephadex G-75 it afforded factor D in yield more than 60% and purity above 100%.