Properdin: preparation from plasma fraction I of the Cohn method.

Pillemer et al. (I) have shown that normal human and other mammalian serums contain a trace protein which has been called properdin. Properdin, in conjunction with complement and YIg++, participates in the natural defense mechanism of blood (2). Pillemer et al. (1) have described a method for preparing properdin from serum. This method employs zymosan to adsorb the properdin, the trace protein being eluted with high ionic strength (p = 0.6) saline. This method has been modified by Pennell et al. (3), starting with plasma obtained from either acid-citratedextrose or resin-collected blood. Rothstein and Pennell (4) have reported the purification of properdin from Fraction I eliminating the use of zymosan. Pondman and Prins (5) have obtained purified properdin from serum utilizing ion-exchange techniques. In an effort to prepare large quantities of purified properdin for clinical evaluation, a number of fractions obtained from the Cohn cold ethanol process (6) were investigated. During our work with these fractions, we were informed by the Protein Foundation Laboratories that they had found properdin activity in Cohn’s Fraction I. This observation was confirmed here and Fraction I has indeed proven to be a rich source of properdin (7). In these laboratories a glycine-citrate buffer extraction step is employed to purify the fibrinogen in Fraction I. Considerable properdin activity was found in this extract and when purified by the methods described in this paper, the glycine-citrate buffer extract yielded high potency properdin.