Cytotoxicity of immunoglobulins from amyotrophic lateral sclerosis patients on a hybrid motoneuron cell line.
Patients with amyotrophic lateral sclerosis possess antibodies (ALS IgGs) that bind to L-type skeletal muscle voltage-gated calcium channels (VGCCs) and inhibit L-type calcium current. To determine whether interaction of ALS IgGs with neuronal VGCCs might influence motoneuron survival, we used a motoneuron-neuroblastoma hybrid (VSC 4.1) cell line expressing binding sites for inhibitors of L-, N-, and P-type VGCCs. Using direct viable cell counts, quantitation of propidium iodide- and fluorescein diacetate-labeled cells, and lactate dehydrogenase release to assess cell survival, we document that ALS IgG kills 40-70% of cAMP-differentiated VSC 4.1 cells within 2 days. ALS IgG-mediated cytotoxicity is dependent on extracellular calcium and is prevented by peptide antagonists of N- or P-type VGCCs but not by dihydropyridine modulators of L-type VGCCs. Preincubating IgG with purified intact L-type VGCC or with isolated VGCC alpha 1 subunit also blocks ALS IgG-mediated cytotoxicity. These results suggest that ALS IgG may directly lead to motoneuron cell death by a mechanism requiring extracellular calcium and mediated by neuronal-type calcium channels.
Smith
R G
RG
Department of Neurology, Baylor College of Medicine, Houston, TX 77030.
Alexianu
M E
ME
Crawford
G
G
Nyormoi
O
O
Stefani
E
E
Appel
S H
SH
D000690:Amyotrophic Lateral Sclerosis / Q000276:immunology*; D000818:Animals; D001323:Autoantibodies / Q000276:immunology*; D002118:Calcium / Q000502:physiology; D015220:Calcium Channels / Q000502:physiology*; D002454:Cell Differentiation; D002460:Cell Line; D003602:Cytotoxicity, Immunologic; D006801:Humans; D051379:Mice; D009046:Motor Neurons / Q000166:cytology / Q000276:immunology*; D051381:Rats
D001323:Autoantibodies; D015220:Calcium Channels; D002118:Calcium