ANTIGEN PRESENTATION BY THYMOMA EPITHELIAL-CELLS FROM MYASTHENIA-GRAVIS PATIENTS TO POTENTIALLY PATHOGENIC T-CELLS

Thymomas associate strongly with myasthenia gravis (MG). We now show that cultured thymoma epithelial cells can present synthetic acetylcholine receptor (AChR) peptides to HLA-sharing responder T cell lines/clones nearly as efficiently as blood mononuclear cells. Responses depended strictly on the specific antigen added. Processing of longer recombinant AChR polypeptides was clearly less efficient than by blood mononuclear cells, and was selectively abolished by preculture with chloroquine. The T cell responses depended on the presence of LFA-3 on the thymoma cells. This study demonstrates that thymoma epithelial cells have the capacity to stimulate T cells and perhaps, therefore, to autosensitize against AChR in vivo.