Spontaneous autoimmune thyroiditis in the BUF rat

The immunological basis of autoimmune disease

Organ-specific diseases often involve cell surface antigens which when functionally characterized prove to have some receptor function. Certain restricted parts of the molecule are autoantigenic but the response to these epitopes is similar to that provoked by foreign antigens with respect to diversity of class, clonality and probably idiotypy. The mechanisms controlling the response to components on the surface of the body's cells are not fully understood but might be circumvented by polyclonal activators or by the development of T suppressor dysfunction. The latter could occur through a generalized defect in T suppressor cells, which would account for the association of autoimmune diseases in given individual subjects. Alternatively, or in addition (since genetic studies suggest multifactorial influences), the suppressor defect could be antigen specific. Our studies in chickens with spontaneous autoimmune thyroiditis show that normal antigen is obligatory for both the development and maintenance of autoantibody production and that it is possible that some abnormality or change in the presentation of the autoantigen (rather than its structure) is concerned in the initiation process.

Subchronic toxicity of pentostatin in Wistar rats

Pentostatin, an adenosine deaminase inhibitor, has been approved for the treatment of refractory hairy cell leukemia. In a preclinical toxicity study, Wistar rats were administered 0, 1, 10, 25, and 50 mg/kg (0, 6, 60, 150, and 300 mg/m2, respectively) pentostatin intravenously once a week for 26 wk (1.5-75-fold above the therapeutic dose in humans). Lymphoplasmacytic thyroiditis was present in 20% of females given 25 mg/kg and in 20 and 47% of males and females given 50 mg/kg, respectively. Thyroiditis was still present 4 wk following drug withdrawal. Thyroiditis was characterized by glandular enlargement, follicular epithelial hyperplasia and degeneration, colloid depletion, and interstitial infiltrates of lymphocytes and plasma cells. Drug-related changes in other tissues included lymphoid depletion of T-cell regions of thymus, spleen, and lymph nodes; bronchiolization of alveolar ducts with accumulation of mucus and foamy macrophages; testicular atrophy with sperm granulomas; dermoepidermal lymphocytic infiltrates with ulceration and alopecia; and hepatocytomegaly.