Analysis of susceptibility of NOD mice to spontaneous and experimentally induced thyroiditis

Beside diabetes, non-obese diabetic (NOD) mice develop sporadic lymphoid infiltration of the thyroid gland, mimicking Hashimoto's thyroiditis. We have examined the prevalence of those manifestations in NOD mice, the influence of the major histocompatibility complex (MHC) and the association with autoantibodies. The incidence at 1 year is of 14.3% in wild-type NOD mice versus 19.6% in congenic NOD.H2(k) mice. The moderate, but statistically significant difference, based on the analysis of 161 NOD and 169 NOD.H2(k) mice, suggests that MHC genes partially control spontaneous NOD thyroiditis. Autoantibodies against thyroglobulin (Tg) are mouse specific and their presence correlates closely with thyroiditis. The strong correlation between cellular and humoral anomalies therefore resembles Hashimoto's thyroiditis. NOD and NOD.H2(k) mice actively immunized against Tg develop severe chronic lesions with epithelium necrosis and interstitial tissue fibrosis. Most interestingly, those lesions do not regress spontaneously as in CBA/J mice. Paradoxically, the response to Tg of lymph node cells from NOD mice is weaker both in proliferation and cytokine production. The defect is most evident for interferon-gamma-producing T cells and is reflected in the marked deficit in IgG2a antibodies. Thus a moderate anti-Tg response seems to favor chronicity of thyroiditis. In conclusion, NOD and NOD.H2(k) mice offer a unique opportunity of analyzing the factors leading to immune chronicity in a genetic context which promotes autoimmune endocrino-pathies.