Sterilizable autoantigen immobilized column platform for broad-spectrum removal of pathogenic autoantibodies in autoimmune diseases.

Blood purification using immunoadsorbent columns is a therapeutic strategy for removing pathogenic autoantibodies in autoimmune diseases. Currently available columns have limitations: Trp/Phe columns offer cost-effectiveness and sterilizability, but lack antigen specificity and have limited capacity to remove diverse pathogenic autoantibodies; whereas Protein A/peptide/anti-human IgG columns target all antibodies, regardless of pathogenicity, limiting specificity, and often require sterile production due to low stability under sterilization conditions, except for peptide ligands. Full-length autoantigen-immobilized immunoadsorbent columns have great potential to specifically adsorb targeted autoantibodies, because autoantibodies recognize diverse epitopes that vary among individuals. However, it is challenging to prepare biologically active autoantigens on a large scale and maintain the quality of antigen-immobilized columns after sterilization. This study introduced a novel approach for preparing sterilizable antigen-immobilized columns that target autoantibodies, excluding those with conformational epitope specificity. Two type I transmembrane protein-coding extracellular domains associated with autoimmunity and their rabbit antisera were used as models. Recombinant human contactin-associated protein-like 2 (Caspr2) and muscle-specific tyrosine-protein kinase receptor (MuSK) were expressed as bacterial inclusion bodies. These compounds were solubilized and purified using Cys-specific chemical cationization. Columns immobilized with water-soluble S-cationized Caspr2 or MuSK effectively captured specific antibodies from rabbit antisera against each antigen, retaining their capacity after standard sterilization. This approach offers a promising solution for developing immunoadsorbent columns with enhanced specificity and sterilizability and is applicable to various autoantibody-related disorders.