Autoantibodies in complex regional pain syndrome bind to a differentiation-dependent neuronal surface autoantigen Danielle Kohr a , Marlene Tschernatsch a , Katrin Schmitz a , Pratibha Singh a , Manfred Kaps a , Karl-Herbert Schäfer e , Martin Diener c , Janina Mathies a , Oliver Matz a , Wolfgang Kummer g , Christian Maihöfner f , Thorsten Fritz b , Frank Birklein d , Franz Blaes a, * a Dept. of Neurology, Justus-Liebig-University, Am Steg 14, 35392 Giessen, Germany b Dept. of Anesthesiology, Justus-Liebig-University, Giessen, Germany c Dept. of Veterinary Physiology, Justus-Liebig-University, Giessen, Germany d Dept. of Neurology, Johannes-Gutenberg-University Mainz, Germany e Dept. of Biotechnology, University of Applied Sciences, Kaiserslautern, Germany f Dep. of Neurology, University Hospital Erlangen, Erlangen, Germany g Dept. of Anatomy and Cell Biology, Justus-Liebig-University, Giessen, Germany article info Article history: Received 27 December 2008 Received in revised form 3 March 2009 Accepted 10 March 2009 Keywords: Complex regional pain syndrome Autoantibodies Antineuronal Autoimmunity Autonomic nervous system Immune system abstract Complex regional pain syndrome, which is characterised by pain and trophic disturbances, develops fre- quently after peripheral limb trauma. There is an increasing evidence of an involvement of the immune system in CRPS, and recently we showed that CRPS patients have autoantibodies against nervous system structures [6]. Therefore we tested the sera of CRPS patients, neuropathy patients and healthy volunteers for surface-binding autoantibodies to primary cultures of autonomic neurons and differentiated neuro- blastoma cell lines using flow cytometry. Thirteen of 30 CRPS patients, but none of 30 healthy controls and only one of the 20 neuropathy sera had specific surface binding to autonomic neurons (p < 0.001). The majority of the sera reacted with both sympathetic and myenteric plexus neurons. Interestingly, 6/30 CRPS sera showed binding to undifferentiated SH-SY5Y neuroblastoma cells. However, differentia- tion of SH-SY5Y into a cholinergic phenotype induced a surface antigen, which is recognised by 60% of CRPS sera (18/30), but not by controls (p < 0.001). Our data show that about 30–40% of CRPS patients have surface-binding autoantibodies against an inducible autonomic nervous system autoantigen. These data support an autoimmune hypothesis in CRPS patients. Further studies must elucidate origin and function of these autoantibodies in CRPS. Ó 2009 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved. 1. Introduction Complex regional pain syndromes (CRPS) may develop particu- larly after peripheral limb trauma, either without (CRPS 1) or with clinically evident peripheral nerve lesions (CRPS 2). The main clin- ical symptoms are pain and hyperalgesia, vasomotor, sudomotor and trophic changes on the affected extremity. In addition, motor symptoms are usually present from the beginning [1,34], and may progress with ongoing duration [32]. Studies on the pathophysiology of CRPS revealed that there are two major mechanisms responsible for the clinical signs of acute CRPS: Exaggerated inflammation after trauma [19], in particular the neurogenic inflammatory component [22,38]; and dysfunction of the sympathetic nervous system [36]. Recent evidence led one focus of research on the involvement of the immune system in CRPS pathogenesis. Some studies revealed that HLA alleles DQ1 [20], DR13 [33], DR15 [25] and the centro- meric regions of the HLA class 1 antigens [30] were linked to CRPS. Furthermore, acute CRPS cases can be sufficiently treated using systemic corticosteroids [7,9]. Accordingly, in a recent study we have been able to demonstrate autoantibodies specifically target- ing autonomic (e.g. sympathetic) nervous system structures [6]. These autoantibodies, which were detected by immunofluores- cence, have been directed against intracellular antigens of sympa- thetic ganglia neurons. Additionally, Goebel et al. could also demonstrate increased binding of CRPS sera to various peripheral and central nervous system structures [12]. However, the underly- ing antigens and pathophysiological role are yet unknown. In well- characterised autoantibody-mediated neuroimmunological dis- eases, such as myasthenia gravis or Lambert–Eaton myasthenic syndrome, pathogenically relevant autoantibodies are directed against surface structures (review in [21]). 0304-3959/$36.00 Ó 2009 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.pain.2009.03.009 * Corresponding author. Tel.: +49 641 9945357; fax: +49 641 9945449. E-mail address: franz.blaes@neuro.med.uni-giesen.de (F. Blaes). www.elsevier.com/locate/pain PAIN Ò 143 (2009) 246–251