SENSITIZATION OF T-LYMPHOCYTES TO THYROGLOBULIN AND THYROPEROXIDASE IN AUTOIMMUNE THYROID-DISEASES

To investigate T-cell sensitization to thyroid autoantigens in autoimm une thyroid discase (AITD), purified soluble human thyroglobulin (Tg) and thyroid peroxidase (TPO) were used. Peripheral blood mononuclear c ells (PBMC) as well as CD8-depleted, CD4-enriched PBMC (''selected'' P BMC) from 9 patients with Graves' disease (GD), 13 Hashimoto's thyroid itis (HT) and 10 healthy subjects, were cultured for 6 days with or wi thout varying concentrations (0.1, 1.0 and 5.0 mug/ml, respectively) o f Tg or TPO and their responses were evaluated using the 3H-thymidine incorporation assay. Total PBMC as well as selected PBMC from GD and H T responded to both TPO and Tg, but normal PBMC did not. This inductio n was more marked in ''selected'' PBMC; on the other hand, CD8 depleti on did not permit normal PBMC to respond to either antigen. However, r eactivity of selected AITD PBMC to Tg differed from that of TPO. Two w ay analysis of variance showed that the proliferative response was sig nificantly greater with Tg than with TPO, (again particularly notable with the ''selected'' PBMC) in both GD and HT. There was no difference between control and AITD preparations when an irrelevant (renal micro somal) antigen was employed. Taken together with our previous report t hat CD4 cells were induced by TPO even when cultured with CD8 cells, i t is evident that suppressor CD8 cells do play a role in CD4 cells fro m proliferating against Tg and TPO; however their function alone or in combination with suppressor-inducer CD4 cells is partially disturbed, so that T cell sensitization to Tg and TPO can be identified in the A ITD PBMC.