Binding of iodine 125 alpha-bungarotoxin to the thymus of mice
F. Ohshima, K. Kondo and T. Tsubaki
alpha-Bungarotoxin is known to bind with nicotinic acetylcholine receptors
of skeletal muscle. Binding of iodine 125-labeled alpha bungarotoxin to the
murine thymus, muscle, and liver was estimated. The toxin was bound to the
muscle. The thymus was also capable of binding a considerable amount of the
toxin, and the binding was obviously blocked by tubocurarine chloride.
Binding to the liver, an organ containing no nicotinic acetylcholine
receptor, was very slight. These results may indicate the presence of
nicotinic acetylcholine receptors in the thymus, which could have
implications in the pathogenesis of myasthenia gravis. Degenerating myoid
cells and their receptors may represent autoantigens that induce an
immunological cross-reaction with the receptors of skeletal muscles, giving
rise to myasthenia gravis.
