Thyroid autoantigen-induced lymphocyte proliferation in Graves' disease and Hashimoto's thyroiditis

Further progress in understanding T-cell interactions in autoimmune thyroid disease would be possible if T-cell lines and clones could be established. We have therefore examined peripheral blood lymphocyte proliferation in response to a variety of thyroid antigens in Graves' disease and Hashimoto's thyroiditis. A number of different culture conditions were used but in all cases the frequency and magnitude of positive responses were low, the maximum stimulation found for any individual culture with antigen being less than 4-fold above background proliferation. In addition we have examined the blastogenic response of Graves' lymphocytes from thyroid, cervical lymph node and thymus. Positive responses were again found but the stimulation produced by antigen was only 3-fold above background. These results are compatible with recent findings in experimental autoimmune thyroiditis and suggest either that very few antigen-specific T cells are involved in the autoimmune process or that antigen-specific cells exist which can suppress the proliferative response in vitro. It therefore seems unlikely that randomly collected peripheral blood T cells from patients with autoimmune thyroid disease can be sufficiently stimulated by thyroid autoantigens to establish lines or clones without additional manoeuvres such as fractionation into subsets.