[Correlation between pathogenesis of myasthenia gravis and thymus mature dendritic cells]

To investigate the correlation between onset of myasthenia gravis (MG) and the changes of the number and distribution of thymus mature dendritic cells (mDC).

The specimens of thymus were obtained during operation from 39 MG patients who hadn't received immunosuppressive therapy before thymectomy and 19 sex- and age-matched patients who underwent cardiosurgery as controls. Immunohistochemistry with antibody against DC-LAMP, specific surface marker of DC, was used to examine the number and distribution of thymus mDCs.

(1) mDCs were restricted in the medulla and cortex-medulla junctional zone of thymus in the control group; while were irregularly distributed in the cortex, medulla, and stroma in the MG group. (2) mDCs presented a roughly uniform distribution in the medulla of thymus in the control group, while clustering distribution was more often in the MG group, especially dense around the germinal center. (3) The relative ratio and numbers of mDCs per average field of vision in the positive areas of the MG group were (10.9% +/- 2.2%) and (50 +/- 9), both significantly higher than those of the control group [(8.5% +/- 1.5%) and (41 +/- 7) respectively, both P < 0.05].

The number and ratio of the thymus mDCs in MG are high, high, and the distribution abnormal. mDC actively may be actively involved in the pathogenesis of MG.