In myasthenia gravis (MG) an autoimmune response against muscle acetylcholine receptor (AChR) occurs. Embryonic muscle AChR contains a y subunit, substituted in adult muscle by a homologous e subunit. Antibodies and CD4 + cells specific for embryonic AChR have been demonstrated in MG patients.We identified sequence segments of the human y subunit forming epitopes recognized by four embryonic AChR-specific CD4' T cell lines, propagated from MG patients' blood by stimulation with synthetic peptides corresponding to the human -y subunit sequence. Each line had an individual epitope repertoire, but two 20-residue sequence regions were recognized by three lines of different HLA haplotype. Most T epitope sequences were highly diverged between the y and the other AChR subunits, confirming the specificity of the T cells for embryonic AChR. These T cells may have been sensitized against AChR expressed by a tissue other than innervated skeletal muscle, possibly the thymus, which expresses an embryonic muscle AChR-like protein, containing a y subunit. Several sequence segments forming T epitopes are similar to regions of microbial and /or mammalian proteins unrelated to the AChR. These findings are consistent with the possibility that T cell cross-reactivity between unrelated proteins ("molecular mimicry"), proposed as a cause of autoimmune responses, is not a rare event. (J. Clin. Invest. 1992Invest. . 90:1558Invest. -1567
We tested the response of CD4' cells and/or total lymphocytes from the blood of 22 myasthenic patients and 10 healthy controls to overlapping synthetic peptides, 20 residues long, to screen the sequence of the y and 5 subunits of human muscle acetylcholine receptor (AChR). The oy subunit is part of the AChR expressed in embryonic muscle and is substituted in the AChRs of most adult muscles by an e subunit. The 5 subunit is present in both embryonic and adult AChRs. Adult extrinsic ocular muscles, which are preferentially and sometimes uniquely affected by myasthenic symptoms, and thymus, which has a still obscure but important role in the pathogenesis of myasthenia gravis, express the embryonic 'y subunit. AntiAChR CD4+ responses were more easily detected after CD8+ depletion. All responders recognized epitopes on both the y and a subunits and had severe symptoms. In four patients the CD4 + cell response was tested twice, when the symptoms were severe and during a period of remission. Consistently, the response was only detectable, or larger, when the patients were severely affected. (J. Clin. Invest. 1993. 92:1055-1067
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.