Mj. Kornstein et al., ACETYLCHOLINE-RECEPTOR ALPHA-SUBUNIT AND MYOGENIN MESSENGER-RNAS IN THYMUS AND THYMOMAS, The American journal of pathology, 146(6), 1995, pp. 1320-1324
Myasthenia gravis is an autoimmune disorder characterized in most case
s by serological antibody against the acetylcholine receptor (AChR). E
vidence for intrathymic localization of AChR suggests that the thymus
has an important role in the pathogenesis of this disorder. Using reve
rse transcription followed by the polymerase chain reaction, we have d
emonstrated AChR alpha-subunit mRNA in thymuses and thymomas from pati
ents with and without myasthenia gravis. We have also studied the expr
ession of myogenin which is known to be involved in the regulation of
AChR expression. By using the reverse transcription polymerase chain r
eaction, we found myogenin mRNAs in all of the thymuses and thymomas.
Thus, both AChR alpha-subunit and myogenin mRNA are present In all of
these specimens. By immunohistochemistry, myoid cells (desmin and myog
lobin positive) were present in all (four of four) thymuses studied an
d in two of five thymomas. Thus, in thymomas, nonmyoid cells might exp
ress both AChR and myogenin. These results indicate that cells within
the thymus and thymoma express AChR and its regulatory protein myogeni
n and that such cells, under certain conditions, might play a role in
the triggering of myasthenia gravis.