Expression of nicotinic acetylcholine receptor subunits in HEp-2 cells for immunodetection of autoantibody specificities in sera from Myasthenia gravis patients

Issue title: Selected Presentations held at the 34th Conference of the German Society for Clinical Microcirculation and Hemorheology, Regensburg, Germany, 27–28 November, 2015

Guest editors: L. Prantl, E.M. Jung and F. Jung

Article type: Research Article

Authors: George, S.^{a; b} | Noack, M.^a | Vanek, M.^a | Rentzsch, J.^a | Röber, N.^b | Conrad, K.^b | Roggenbuck, D.^{a; c} | Küpper, J.-H.^{a; *}

Affiliations: [a] Faculty of Science, Brandenburg University of Technology Cottbus-Senftenberg, Germany | [b] Institute of Immunology, Medical Faculty of the Technical University of Dresden, Germany | [c] Generic Assays GmbH, Dahlewitz, Germany

Correspondence: [*] Corresponding author: Jan-Heiner Küpper, Faculty of Science, Brandenburg University of Technology, Großenhainer Str. 57, 01968 Senftenberg, Germany. Tel.: +49 357385930; Fax: +49 357385809; E-mail: jan-heiner.kuepper@b-tu.de

Abstract: Myasthenia gravis (MG) is an autoimmune disease characterized by the formation of pathogenic autoantibodies mostly targeting the nicotinic acetylcholine receptor (AChR). The AChR is composed of two alpha subunits and one subunit of each beta, delta and gamma (fetal AChR), or epsilon (adult AChR), respectively. Serological diagnostics is commonly done by radioimmunoassay (RIA). Here we used an indirect immunofluorescence assay with MG patient sera on transiently transfected HEp-2 cells expressing selected components of the AChR. Our data show that already 12 out of 13 MG patient sera showed autoantibody binding to HEp-2 cells transfected to express the alpha subunit solely. Interestingly, 11 out of 13 patient sera reacted positive with cells transfected to reconstitute the complete fetal AChR, but only 6 out of 13 sera showed positive signals with cells expressing the components of adult AChR. Moreover, there was no strict correlation of the serum concentration required to obtain clear-cut fluorescence signals to the antibody titer as measured by RIA. It will be an interesting topic to further investigate if the optimal serum dilution for indirect immunofluorescence as well as the autoantibody binding preferences to defined AChR subunits and to the adult versus the fetal receptor variant could provide additional predictive value in MG diagnostics.

Keywords: Acetylcholine receptor, autoantibodies, cell-based assay, HEp-2 cells, indirect immunofluorescence, multiplex diagnostics, Myasthenia gravis, radioimmunoassay, serological diagnostics

DOI: 10.3233/CH-151999

Journal: Clinical Hemorheology and Microcirculation, vol. 61, no. 2, pp. 385-396, 2015