Specificities of antibodies to acetylcholine receptors.

Antisera to acetylcholine receptor purified from the electric organs of Torpedo and Electrophorus were highly species specific, but showed limited cross-reaction with receptors from all mammalian species tested. Antisera to receptor purified from rat muscle cross-reacted extensively with receptor from the muscles of other mammals. Antibodies to receptor from Electrophorus cross-reacting with receptor from Torpedo were affinity purified. Subsequently these showed increased cross-reaction with receptor from mammalian muscle. Sera from patients with myasthenia gravis reacted best with receptor from human muscle, but such sera also cross-reacted with receptor from other mammals, especially squirrel monkeys. These sera cross-reacted slightly with receptor from Torpedo, but not detectably with receptor from Electrophorus,