| Abstract: | Experimental autoimmune thyroiditis could be produced in SMA, C3H/He and C57BL mice by repeated injection at intervals of 30 days of syngeneic thyroid extract mixed with the capsular polysaccharide of Klebsiella pneumoniae (CPS-K) as a powerful adjuvant. The sequence of the development of autoimmune thyroiditis was histologically followed using SMA strain of mice, in which the thyroid lesions were most marked. A single injection of the thyroid extract mixed with CPS-K induced interstitial infiltration of small lymphocytes and other mononuclear cells, and follicular architecture was partially damaged. At early times (5 to 12 days) after the secondary injection of the material, there were aggregation of polymorphonuclear neutrophilic leukocytes with formation of microabscesses in the follicles and hyaline degeneration of small vessels in the thyroid glands, suggesting that this stage of the thyroid lesions was expression of an Arthus reaction. The maximal severity of the thyroid lesions was reached at 30 days after the secondary injection. At this time, the thyroid lesions consisted of extensive infiltration of small lymphocytes, plasma cells and other mononuclear cells with complete loss of follicular architecture and mild proliferation of fibrous connective tissues. Even at 200 days after the secondary injection, there was no evidence of spontaneous regression and resolution of the thyroid lesions. Based on the histological findings, it seems likely that in our system cell-mediated immunity plays a dominant role in initiation and maintenance of thyroiditis and humoral antibodies do so in its aggravation. |
