Ninhydrin sweat test: a simple method for detecting antibodies neutralizing botulinum toxin type A.
Approximately 5% of patients with cervical dystonia receiving repeated botulinum neurotoxin A (BoNT/A) injections develop secondary loss of treatment benefit. Currently available tests to directly detect neutralizing BoNT/A antibodies (BoNT/A-AB) are either expensive or time consuming. To establish a simple, clinically useful test for antibody detection, we adapted the ninhydrin sweat test (NST). Eighteen dystonic patients with secondary nonresponse and clinically suspected BoNT/A-AB formation were tested for BoNT/A-AB in the mouse diaphragm test (MDT). In addition, the size of the anhidrotic area was determined by the NST 21 days after an intradermal dose of 10 U Dysport into the hypothenar region of the left palm. In nine patients, positive BoNT-AB titers were found in the MDT. There was a significant correlation between the BoNT/A-AB titers and the anhidrotic area (Spearman's rho = -0.9, P < 0.0001). Both tests provided comparably good results with respect to qualitative antibody detection. In the clinical situation of secondary nonresponse to BoNT/A therapy, the economical NST may be a helpful tool to detect neutralizing BoNT/A-AB.
Department of Neurology, Division of Neurorehabilitation, University of Vienna, Austria. bernhard.voller@meduniwien.ac.at
Bernhard
B
Voller
Ekaterina
E
Moraru
Eduard
E
Auff
Michael
M
Benesch
Werner
W
Poewe
Jörg
J
Wissel
Jörg
J
Müller
Tanja
T
Entner
Hans
H
Bigalke
Peter
P
Schnider
D000328:Adult; D000818:Animals; D000906:Antibodies / Q000032:analysis* / Q000097:blood / Q000494:pharmacology; D000937:Antigen-Antibody Reactions; D019274:Botulinum Toxins, Type A / Q000276:immunology* / Q000627:therapeutic use; D020821:Dystonic Disorders / Q000188:drug therapy / Q000276:immunology*; D005260:Female; D006225:Hand / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000276:immunology / Q000627:therapeutic use; D009469:Neuromuscular Junction / Q000187:drug effects; D009555:Ninhydrin / Q000737:chemistry*; D013542:Sweat / Q000737:chemistry / Q000276:immunology*
D000906:Antibodies; D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A; D009555:Ninhydrin