2.5. Column chromatography and nylon prefilter
Protein solutions spiked with aggregate were processed and applied to
liquid column chromatography conducted using an AKTA avant 25 or an AKTA
pure 25 (GE Healthcare) with the following types of chromatography
resins. For mAb solutions, mixed-mode AEX1
(weak AEX of primary amine in
combination with weak HIC of butyl group; Cellufine MAX IB), mixed-mode
AEX2 (strong AEX with quaternary amine and phenyl group in combination
with strong HIC; Capto adhere, GE Healthcare) and normal AEX (Cellufine
MAX Q-h) were used. For plasma IgG solutions, mixed-mode AEX1 and normal
AEX were used along with modified CEX1 (cross-linked cellulose with
dextran sulfate; Cellufine MAX DexS-HbP), and modified CEX2 (sulfated
cellulose; Cellufine Sulfate). All Cellufine resins were supplied by JNC
Corporation.
Additionally, nylon prefilter Virosart Max Minisart (5
cm2 surface area, Sartorius), which is considered to
be effective for removing aggregates, was used as a treatment for
aggregate-spiked mAb solution.