Membrane pore size and filtration selectivity in cryoglobulinemic plasma fractionation

Efficiency of albumin (Alb) and immunoglobulin G (IgG) separation from cryoprecipitable proteins (CPP) and IgM was compared between a membrane plasma fractionator with a mean pore diameter (MPD) of 0.1 micron, surface area of 0.65 m2, and a new large pore diameter filter with a MPD of 4.3 microns, and surface area of 0.14 m2. In five in vitro tests at 4 degrees C using polyclonal cryoglobulinemic (CG) plasma from a patient treated by plasma exchange (PE), the large pore filter retained only 22% of the mass of Alb, and a comparable amount of CPP and IgM, as compared to the plasma fractionator, at a fraction of its total retention capacity. The new filter can replace PE in treatment of polyclonal CG.