Selected IgG rapidly induces Lambert–Eaton myasthenic syndrome in mice: Complement independence and EMG abnormalities
Version of Record online: 13 OCT 2004
Copyright © 1988 John Wiley & Sons, Inc.
Muscle & Nerve
Volume 11, Issue 11, pages 1133–1145, November 1988
How to Cite
Lambert, E. H. and Lennon, V. A. (1988), Selected IgG rapidly induces Lambert–Eaton myasthenic syndrome in mice: Complement independence and EMG abnormalities. Muscle Nerve, 11: 1133–1145. doi: 10.1002/mus.880111105
- Issue online: 13 OCT 2004
- Version of Record online: 13 OCT 2004
- Manuscript Accepted: 9 DEC 1987
Antibodies in individual patients with the Lambert–Eaton myasthenic syndrome (LES) differ in their reactivity with mouse motor nerve terminals. Of 26 LES patients' sera injected a single time into mice, 3 caused a highly significant reduction in stimulus-dependent quantal release (m) of acetylcholine (ACh) (to 6, 33, and 42 quanta per impulse at 1 Hz, respectively; mean for 10 control sera, 100 quanta at 1 Hz). The most potent serum (LES-A) was fully effective in mice deficient in complement component C5 and in mice depleted of complement components C3C9 by cobra venom factor. A single i.v. injection of serum reduced m in direct proportion to log dose. Responses to K+ depolarization and increasing concentrations of Ca2+ were like those observed in human LES.
With LES-A serum, or its IgG, m was reduced near maximally in 1 day and plateaued in 3–4 days. Recovery began after day 8; m was in the normal range by day 20–30. Electromyographic (EMG) abnormalities were not seen until m fell below 40 quanta per impulse at 1 Hz. Below 10 quanta, clinical signs of weakness appeared, and the EMG abnormalities were those classically associated with LES: a marked reduction of compound muscle action potential to a single nerve stimulus in rested muscle, a further decrement during stimulation at slow rates, but marked facilitation during rapid repetitive stimulation.