Inhibition of T cell proliferation specific for acetylcholine receptor epitopes related to myasthenia gravis with antibody to T cell receptor or with competitive synthetic polymers.

Long-term T cell lines and clones of C3H.SW origin specific to synthetic peptides representing immunogenic epitopes of the human aetylcholine receptor alpha-subunit were established. Using these lines and clones, it was possible to characterize the T cell recognition process of myasthenic epitopes. Testing a panel of N-and/or C-terminal truncated peptides it could be demonstrated that the deletion of the two C-terminal amino acids of peptides p195-212 and p259-271 resulted in a loss or reduction of the stimulatory capacity of the peptides towards the specific T cell lines. In contrast, no substantial effect on the stimulation of the line could be observed by shortening peptide p195-212 by up to five amino acids at the N-terminal end. The proliferation of T cell lines and clones specific to peptide p195-212 was inhibited by a mAb directed against the V beta 8 region of the T cell receptor. Furthermore, it was possible to block the peptide-specific proliferative responses of the lines and clones by the I-Ab restricted synthetic polypeptide (T, G)-A--L but not by the I-Ak restricted polypeptide antigen (H,G)-A--L. Similarly, p195-212 inhibited the proliferative response of the TCSW259-271 T cell line and p259-271 inhibited the specific proliferative response of the TCSW195-212 line. Moreover, the C-terminal shortened peptides inhibited significantly the in vitro stimulation of the T cell lines by the immunogenic peptides p195-212 and p259-271. The inhibition by the synthetic peptides or by (T,G)-A--L may be due to competitive blockade of the MHC binding site for the T cell line stimulating AChR peptides.