Helmar C. Lehmann

Background and purpose It is not known whether the route of administration affects the mechanisms of action of therapeutic immunoglobulin in chronic inflammatory demyelinating polyneuropathy (CIDP). The aim of this study, therefore, was to compare the immunomodulatory effects of intravenous (IVIg) and subcutaneous immunoglobulin (SCIg) in patients with CIDP and in IVIg‐treated common variable immunodeficiency (CVID) patients. Methods Serum and peripheral blood mononuclear cell samples were obtained from 30 CIDP patients receiving IVIg, 10 CIDP patients receiving SCIg, and 15 patients with CVID receiving IVIg. Samples and clinical data were obtained prior to IVIg/SCIg and at 3 days, 7 days, and, in CIDP patients receiving IVIg, 21 days post‐administration. Serum cytokines were assessed by Luminex‐based multiplex assay and enzyme‐linked immunosorbent assay. Immune cells were characterized by flow cytometry. Results Immune cell profiles of CIDP and CVID patients differed in frequencies of myeloid dendritic cells and cytotoxic natural killer cells. During treatment with IVIg or SCIg in CIDP patients, cellular immunomarkers were largely similar. CIDP patients receiving IVIg had higher macrophage inflammatory protein (MIP)‐1α ( p = 0.01), interleukin (IL)‐4 ( p = 0.04), and IL‐33 ( p = 0.04) levels than SCIg recipients. IVIg treatment more broadly modulated cytokines in CIDP than SCIg treatment. Conclusions Our study demonstrates that the modulation of cellular immunomarkers in CIDP is independent of the application route of therapeutic immunoglobulin. Minor differences were observed between CIDP and CVID patients. In contrast, cytokines were differentially modulated by IVIg and SCIg in CIDP.