Antigens associated with N- and L-type calcium channels in Lambert-Eaton myasthenic syndrome.
In Lambert-Eaton myasthenic syndrome neurotransmitter release is reduced by an autoimmune response directed against the calcium channel complex of the nerve terminal. Autoantibodies were detected by immunoprecipitation assays using solubilized receptors labeled with ligands selective for N-type (125I-omega conotoxin GVIA) and L-type ([3H]PN200-110) calcium channels. Sera with a high antibody titer (> 3 nM) against rat brain N-type channels contained autoantibodies that immunoprecipitated neuronal and muscle L-type channels. These IgG fractions stained a 55-kDa protein in immunoblots of purified skeletal muscle dihydropyridine receptor, suggesting that they contain autoantibodies against the beta subunit of the calcium channel. A distinct antibody population in the same fractions reacted with a nerve terminal 65-kDa protein that is unrelated to the beta subunit and displays properties similar to those of synaptotagmin.
el Far
O
O
INSERM U374, Institut Jean Roche, Faculté de Medécine Secteur Nord, Marseille, France.
Marquèze
B
B
Leveque
C
C
Martin-Moutôt
N
N
Lang
B
B
Newsom-Davis
J
J
Yoshida
A
A
Takahashi
M
M
Seagar
M J
MJ
D000818:Animals; D001323:Autoantibodies / Q000032:analysis; D001324:Autoantigens / Q000276:immunology*; D001921:Brain / Q000378:metabolism; D015220:Calcium Channels / Q000145:classification / Q000276:immunology*; D020746:Calcium Channels, L-Type; D007074:Immunoglobulin G / Q000032:analysis; D017275:Isradipine / Q000378:metabolism; D015624:Lambert-Eaton Myasthenic Syndrome / Q000276:immunology* / Q000378:metabolism*; D009124:Muscle Proteins / Q000276:immunology; D018482:Muscle, Skeletal / Q000378:metabolism; D009411:Nerve Endings / Q000276:immunology; D009474:Neurons / Q000378:metabolism; D011233:Precipitin Tests; D051381:Rats
D001323:Autoantibodies; D001324:Autoantigens; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D007074:Immunoglobulin G; D009124:Muscle Proteins; C053157:omega-conotoxin receptor; D017275:Isradipine