Lymphocyte locomotion in experimental allergic thyroiditis

Experimental allergic thyroiditis was produced in rats by immunization with homologous thyroglobulin (Tg). The mechanisms of lymphocyte accumulation of the thyroid lesion were analyzed by using this experimental model. The sensitized lymph node cells were cultured with Tg. After 72 hr, the cell-free supernatant was found to contain a chemotactic factor for sensitized lymphocytes. Lymph node lymphocytes from animals immunized 3 weeks previously were the best source of such sensitized lymphocytes while the cells at the latter stage could not produce the factor. The culture supernatant was applied to a Sephadex G-100 gel filtration column. The results indicate that the molecular weight of the factor is around 12,400. Among lymph node lymphocytes, nylon-wool column nonadherent lymphocytes were the most responsive; adherent lymphocytes were not responsive. Thyroglobulin itself did not chemoattract lymphocytes obtained from rats immunized with Tg. This phenomenon was in contrast to macrophage chemotaxis in the same model in which macrophage itself can move toward Tg. In any event, these results seem to indicate that a chemotactic lymphokine may be playing an important role in the pathogenesis of lymphocyte accumulation of the thyroid lesion.