Immunoadsorbent apheresis eliminates pathogenic IgG in childhood lupus nephritis

BACKGROUND: It is suggested that the highly cation-charged fraction of the IgG and IgG3 subclasses may play a pathogenic role in lupus nephritis. In contrast, immunoadsorbent therapy using a sodium dextransulfate fixed cellulose gel column-low invasive selective immunoadsorbent apheresis therapy (SDSC-IAT) has been applied to lupus nephritis with favorable results. However, elimination using pathogenic IgG by SDSC-IAT has never been investigated. METHOD: Two patients with diffuse proliferative lupus nephritis were treated using SDSC-IAT concomitant with immunosuppressive therapy. The eluates from the SDSC, and the patients' serum obtained before and just after SDSC-IAT were subjected to an IgG charge analysis using isoelectric focusing and immunoblotting, and also to laser nephelometry assay, which is used for measuring IgG subclass concentration. Indirect immunofluorescence staining was performed to detect IgG subclass deposition in the glomerulus. RESULTS: Both of the patients had an immediate decrease in anti-double-strand DNA antibody and in the circulating immune complex with a following clinical improvement. Repeated biopsies demonstrated improvement of glomerular lesions with a marked reduction of IgG and C3 deposition. The IgG of the SDSC eluates consisted of highly cation charged (isoelectric points: 9-10) fractions. In addition, IgG3 was specifically removed from the patients' serum using an SDSC among the IgG subclasses. The subclass of deposited IgG in the glomeruli showed IgG3 predominance. CONCLUSION: SDSC-IAT specifically removed the highly cation charged fractions of IgG and IgG3 from the patients' serum and the elimination of these fractions may have resulted in clinical improvement.