Expression of alpha-3, alpha-5, and beta-4 neuronal acetylcholine receptor subunit transcripts in normal and myasthenia gravis thymus. Identification of thymocytes expressing the alpha-3 transcripts.

We used amplification of reverse transcribed RNA to investigate the thymic transcription of genes encoding for subunits of neuronal acetylcholine receptors (AcChR). All thymic tissues investigated, which include normal thymi, myasthenic hypertrophic thymi, and both myasthenic and nonmyasthenic thymomas, express transcripts encoding for the alpha-3, the alpha-5, and the beta-4 subunits of AcChR. The thymic transcription of at least three different genes encoding for neuronal AcChR subunits suggests there is expression of neuronal AcChR in thymus. Amplification of reverse transcribed RNA and Northern blotting of thymic and peripheral immunocytes showed that thymocytes but not peripheral lymphocytes express alpha-3 AcChR subunit transcripts. This finding suggests that within the T cell lineage there is transcriptional regulation of the alpha-3 AcChR gene.