Isolation of Properdin From Human Plasma.

Abstract

The zymosan technique of isolation of properdin from human serum reported by Pillemer et al (1954) was successfully applied to human plasma, collected over ion exchange resins (IRC-50 or Dowex-50) or in ACD (acid-citrate-dextrose) solution. Refinements in the technique were introduced. The temperature of incubation for adsorption of properdin on zymosan was changed from 17[degree]C to 25[degree]C. The adjustment of the plasma pH to 6.9 is accomplished by use of an acetate buffer, pH 4, ionic strength 0.2, instead of 1 N HCl. This can also be done by layering the surface of the plasma with CO2. The volume of solution employed for elution of properdin from zymosan is now 1/8 plasma volume, instead of 1/2 plasma volume. It was found that properdin activity can be precipitated from the eluate by 25 m[image] Zn++ glycinate at pH 7.1-7.5. The precipitate is dissolved in a small volume of 0.25 [image] ethylenedlaminetetraacetate (EDTA) and then dialyzed, dialysis volume and time being greatly reduced. Even though recovery of properdin activity is reduced with increased age of the plasma, due to disappearance of necessary cofactors, enough activity can be recovered from outdated plasma to make the approach plausible. Preliminary results indicate the presence of properdin in Cohn Plasma Fraction I, using the cold-ethanol method 6 of Cohn et al. Direct fractionation of properdin without the use of zymosan appears probable.