ESTABLISHMENT AND CHARACTERIZATION OF AN ANTIHUMAN THYROTROPIN (TSH) RECEPTOR-SPECIFIC CD4(+) T-CELL LINE FROM A PATIENT WITH GRAVES-DISEASE - EVIDENCE FOR MULTIPLE T-CELL EPITOPES ON THE TSH RECEPTOR INCLUDING THE TRANSMEMBRANE DOMAIN

From the peripheral lymphocytes of a. patient with Graves' disease, we established a T cell. line using its reaction to a pool of 49 synthetic peptides corresponding to the entire human thyrotropin receptor (TSHR) sequence, This T cell line showed a specific response to the pool of peptides in a microproliferation assay (stimulation index: 4.8), Flow cytometry analysis revealed that the cell surface markers were CD4(+)CD8(-), T cell receptor (TcR) alpha beta(+), and TcR gamma delta(-). To investigate T cell epitopes on TSHR, the 49 synthetic peptides were divided into 6 groups, and the responses of the T cell line to each group were tested, The T cell line reacted well against three groups: the N-terminal (amino acids 31-169) and C-terminal (338-420) regions of the extracellular domain and the N-terminal half (441-661) of the transmembrane domain of the receptor, This suggests a multiplicity of T cell epitopes on the TSHR, and was further supported by analysis of TcR gene expression in the cell line that showed the expression of 5 V alpha genes: V alpha-1, 2, 10, 20, and w25, In conclusion,the results of the present study indicated multiple T cell epitopes on the TSHR molecule including the transmembrane domain.