Study on B cell subsets producing ongan-specific autoantibodies

CD5^+B细胞和CD5^-B细胞存在于B细胞亚群中。我们之前发现CD5^+B细胞在自身免疫性甲状腺疾病以及其他自身免疫性疾病中增加。Graves病甲状腺功能亢进时CD5^+B细胞数量比甲状腺功能正常时增加更多，并与血清甲状腺激素或甲状腺自身抗体水平相关。因此，我们研究了哪种B细胞亚群产生甲状腺自身抗体，以及甲状腺激素是否会增加CD5^+B细胞。我们使用细胞分选器（FACStar）从自身免疫性甲状腺疾病患者外周血单个核细胞中分离出CD5^+B细胞和CD5^-B细胞。每个B细胞亚群与B细胞和T细胞有丝分裂原刺激下辐照的自体淋巴细胞为饲养细胞培养7 d。然后，我们用ELISPOT法明确了CD5-B细胞产生igg类甲状腺过氧化物酶抗体和甲状腺球蛋白抗体。然而，我们没有发现产生tsh受体抗体的B细胞亚群。有趣的是，igm类甲状腺自身抗体是由CD5^+B和CD5^-B细胞产生的。另一方面，我们给C57BL/6J小鼠注射甲状腺素或PTU 1-6个月，使小鼠甲状腺功能亢进或减退。双色流式细胞术检测脾淋巴细胞亚群。甲状腺功能亢进小鼠NK细胞和T细胞增加，甲状腺功能低下小鼠CD5^-B细胞增加。CD5^+B细胞不随血清甲状腺激素水平变化。此外，由于桥本病加重，破坏性甲状腺毒症患者的CD5^+B细胞减少，尽管血清甲状腺激素水平升高。这些数据提示CD5^+B细胞可能影响CD5^-B细胞产生甲状腺抗体，并且CD5^+B细胞的增加可能是Graves病发病的基础。

CD5^+B cells and CD5^-B cells are present in a B cell subpopulation. We previously found that CD5^+B cells are increased in autoimmune thyroid disease as well as in other autoimmune diseases. The number of CD5^+B cells is increased more in the hyperthyroid state than in the euthyroid state in Graves' disease, and is correlated with the serum levels of thyroid hormones or thyroid autoantibodies. Therefore, we examined which subset of B cells produces thyroid autoantibodies, and whether thyroid hormones may increase CD5^+B cells.We separated CD5^+B cells and CD5^-B cells from peripheral blood mononuclear cells from patients with autoimmune thyroid disease by using a cell sorter (FACStar). Each subset of B cells was cultured for 7 days with feeder cells of irradiated autologous lymphocytes in stimulation with B and T cell mitogens. Then, we clarified that CD5-B cells produce IgG-class of thyroid-peroxidase antibodies and of thyroglobulin antibodies by using ELISPOT assay. However, we did not identify a B cell subset producing TSH-receptor antibodies. Interestingly, IgM-class of thyroid autoantibodies was produced by both CD5^+B and CD5^-B cells.On the other hand, we administrated thyroxine or PTU to C57BL/6J mice for 1-6 months to make hyper- or hypothyroid mice. Splenic lymphocyte subsets were examined by two-clour flow cytomotry. NK cells and T cells were increased in hyperthyroid mice, and CD5^-B cells were increased in hypothyroid mice. CD5^+B cells were did not change with the serum levels of thyroid hormone. Furthermore, CD5^+B cells decreased in patients with destructive thyrotoxicosis due to the aggravation of Hashimoto's disease, even though the serum levels of thyroid hormones increased.These data suggest that CD5^+B cells may affect the production of thyroid-antibodies by CD5^-B cells, and that the increase of CD5^+B cells might be fundamental in the pathogenosis of Graves' disease.