POSSIBLE ROLE OF HUMAN FOAMY VIRUS IN GRAVES-DISEASE

Human foamy virus (HFV) is a member of the retroviral family of Spumar etrovirinae. In addition to the three retroviral structural genes, gag , pol and env, HFV also contains regulatory sequences, called bel. Foa my viruses have been previously associated with human thyroid disease, notably DeQuervain's thyroiditis. In indirect immunofluorescence test s we have demonstrated the reactivity of the thyroid glands of 7/7 pat ients with Graves' disease and antibodies to HFV gag proteins. No reac tivity was observed with antibodies to pol, env and bel proteins. Nine thyroids of patients with struma parenchymatosa, 4 with follicular ca rcinoma and 2 normal thyroids were negative throughout. From the thyro ids of 5 patients with Hashimoto's disease, 4 were negative and 1 show ed a single small focus of anti-gag antibody reactivity. The uniform i mmunofluorescent staining was restricted to the basal and lateral inte rcellular areas between the thyroid epithelial cells. Extension of the se studies to the retrobulbar tissue of 1 Graves' disease patient with malignant exophthalmus revealed positive staining with anti-gag antib odies of fibroblasts and fat cells but not eye muscles. Furthermore, w e were successful in establishing several T-cell lines derived from th e retrobulbar tissue of this patient. They were CD8+ and proliferated, in contrast to peripheral blood cells, upon cocultivation with autolo gous retroorbital fibroblasts. It remains to be determined whether the se observations are of relevance in the pathogenesis of Graves' diseas e.