Influence of human myasthenia gravis thymus on the differentiation of human cord blood stem cells in SCID mice.

The normal thymus contributes to T lymphocytes differentiation and induction of tolerance to self-antigens. Myasthenia gravis (MG) is characterized by abnormal thymic hyperplasia. To assess the potential influence of MG-thymus on the differentiation of T lymphocytes differentiation, we used the MG-thymus transplanted severe combined immunodeficiency (SCID) mice model to evaluate the human cord blood stem cells differentiation. Thymus fragments from MG patient and human cord blood stem cells were transplanted into SCID mice successively. SCID mice were observed to develop sustained human T lymphocytes and a functional anti-tumor immune. The levels of various T cell subsets in SCID mice with MG-thymus were different from that of control group. Among that, the frequency of CD4(+)CD25(+) T cells was significant lower in SCID mice with MG-thymus. The deficiency of CD4(+)CD25(+) T cells seens to contribute to the pathogenesis of MG.