[Effect of intrathyroidal lymphocytes of Graves' disease patients on xenograft thyroid tissue in the athymic nude mouse].

In this study we investigated the functional and morphological properties of xenotransplanted human thyroid tissue in nude mice following systemic application of intrathyroidal lymphocyte preparations from patients with Graves' disease (GD) and non-toxic nodular goiter (NTG). Thyroid tissue samples from 17 NTG-patients were transplanted into athymic nude mice for a period of 4-5 weeks. Aliquots of lymphocyte preparations from both peripheral blood samples (PBL) and thyroid tissue (ITL) of 13 patients with GD and 12 patients with NTG were analyzed by flow-cytometry (CD3, CD4, CD8, CD56) and injected (i.v.) into transplanted nude mice. Animals injected with saline solution served as a control. After 48 h transplants were harvested and histological (H&E) as well as immunohistological evaluation was performed (MHCII, IgG, IgM). Control animals and mice treated with both PBL and ITL from NTG patients showed regular thyroid tissue without lymphocytic infiltrates or local expression of human immunoglobulins. Application of PBL and ITL of GD patients caused scant to moderate lymphocytic infiltrates with detection of human immunoglobulin production. Injection of GD-ITL was accompanied by a significantly higher proportion of intrathyroidal CD3+ lymphocytes and MHCII expression of adjacent thyroid epithelium as compared to injection of GD-PBL preparations. Our results demonstrate that GD-lymphocytes of both peripheral but especially intrathyroidal origin migrate specifically to human thyroid transplants in the nude mouse model, survive for at least two days, secrete immunoglobulins and induce MHCII expression.