Different Patterns of Autoantibody Secretion by Peripheral Blood Mononuclear Cells in Autoimmune Nodopathies

Abstract

Background and ObjectivesAutoimmune nodopathies with antibodies against the paranodal proteins show a distinct phenotype of a severe sensorimotor neuropathy. In some patients, complete remission can be achieved after treatment with rituximab whereas others show a chronic course. For optimal planning of treatment, predicting the course of disease and therapeutic response is crucial. MethodsWe stimulated peripheral blood mononuclear cells in vitro to find out whether secretion of specific autoantibodies may be a predictor of the course of disease and response to rituximab. ResultsThree patterns could be identified: In most patients with anti-Neurofascin-155-, anti-Contactin-1-, and anti-Caspr1-IgG4 autoantibodies, in vitro production of autoantibodies was detected, indicating autoantigen-specific memory B cells and short-lived plasma cells/ plasmablasts as the major source of autoantibodies. These patients generally showed a good response to rituximab. In a subgroup of patients with anti-Neurofascin-155-IgG4 autoantibodies and insufficient response to rituximab, no in vitro autoantibody production was found despite high serum titers, indicating autoantibody secretion by long-lived plasma cells outside the peripheral blood. In the patients with anti-pan-Neurofascin autoantibodies-all with a monophasic course of disease-no in vitro autoantibody production could be measured, suggesting a lack of autoantigen-specific memory B cells. In some of them, autoantibody production by unstimulated cells was detectable, presumably corresponding to high amounts of autoantigen-specific plasmablasts-well in line with a severe but monophasic course of disease. DiscussionOur data suggest that different B-cell responses may occur in autoimmune nodopathies and may serve as markers of courses of disease and response to rituximab.