The remarkable proliferation of helper T cell subset in response to autologous thyrocytes and intrathyroidal T cells from patients with Graves' disease.

We have studied cellular interactions among thyrocytes, intrathyroidal T cells and peripheral blood T cells from Graves' patients. In the autologous mixed lymphocyte reaction of Graves' patients, CD4+ cells were able to proliferate vigorously against autologous non-T cells, whereas CD8+ cells responded weakly to non-T cell stimulators. Furthermore, the proliferative response of the CD4+ 2H4+ suppressor-inducer T cell subset was increased like that of the CD4+ 2H4- helper T cell subset. In contrast to peripheral blood non-T cell stimulators, thyrocytes and intrathyroidal T cells had the ability to activate the CD4+ 2H4- helper T cell subset but were not able to cause proliferation both of CD4+ 2H4+ suppressor-inducer T cell and CD8+ suppressor/cytotoxic T cell subsets. The marked reduction in proliferative responses of CD4+ 2H4+ cells and CD8+ cells could not be attributed to a difference in kinetics or altered response to variable number of stimulator cells. On the basis of these findings, it is suggested that the concentration of the helper T cell subset may be progressively increased and suppressor circuits may be unable to be activated in thyroid tissues. These abnormalities in cellular interactions may induce the excessive production of autoantibodies.