[Spontaneous Hashimoto-like thyroiditis in cats]. / Spontane Hashimoto-artige Thyreoiditis im Modell der Katze.

A breeding line of domestic cats spontaneously developing symptoms of hypothyroidism between the 40th and 60th day of life (fur changes, loss of appetite, growth retardation), elevated levels of antibodies against microsomal structures and thyroglobulin, and lymphocytic thyroid infiltration has been recently established at our facility. Aim of our studies was to examine the effect of high iodine ingestion or prophylactic thyroid hormone therapy on functional and morphological characteristics of this Hashimoto-like thyroiditis in cat. From birth to day 80 of life cats were treated with iodine (n = 9; 0.1 mg/l) or thyroxin (n = 13; 2.0 micrograms/ kg/d) respectively. Untreated animals served as controls (n = 12). Cat-serum was tested for thyroid function (TT3, TT4). After 8 weeks the thyroid tissue was submitted to routine histological processing (H&E) and the inflammatory activity was scored. Additionally immunohistological staining was performed for MIB-1, IgG, IgM and MHCII expression. Both untreated hypothyroid (UHC) as well as iodine-treated (IC) cats revealed a significantly higher degree of thyroid inflammation and higher tissue levels of IgM as the thyroxin-substituted animals (TC). Epithelial proliferation decreased significantly in the IC and TC groups as compared to the untreated controls. No significant differences regarding IgG production and HLAII expression were detectable. Early thyroid hormone therapy significantly decreases both incidence and activity of autoimmune thyroiditis in cats as measured by inflammatory infiltration, IgM production and epithelial proliferation. Animals with excess iodide intake, however, show an aggravation of the autoimmune inflammatory activity.

[Effect of intrathyroidal lymphocytes of Graves' disease patients on xenograft thyroid tissue in the athymic nude mouse]. / Einfluss intrathyreoidaler Lymphozyten von Basedow-Patienten auf xenotransplantiertes Schilddrüsengewebe in der thymusaplastischen Nacktmaus.

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.