AbstractCross-linked cellulose microspheres (CL-CMs) were successfully prepared using an inverse crosslinking suspension method from a cellulose solution with sodium hydroxide/urea aqueous solution as a solvent and epichlorohydrin as the crosslinker. The effects of epichlorohydrin content on the appearance and dispersity, average pore volume, moisture content, and wet real density of CL-CMs were studied. The microspheres presented a good spherical shape and porous surface structure. After activation with NaIO4, the recombinant protein A was immobilized onto the surface of CL-CMs to form an immunoadsorbent. Adsorbents containing various amounts of protein A were applied to adsorb immunoglobulin G (IgG) from human plasma. The maximum IgG adsorption capacities with static adsorption and dynamic adsorption were 23 and 13 mg, respectively, per gram of CL-CMs carrying 6.8 mg of recombinant protein A. Therefore, CL-CMs immobilized with recombinant protein A have great potential for application in the field of blood purification.