Transplantation of myasthenia gravis thymus to SCID mice

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.

The Role of Thymomas in the Development of Myasthenia Gravis

Thymic pathology occurs in 80-90% of myasthenia gravis patients. Significant associations between different thymic alterations and clinical findings are discussed. To highlight peculiarities in thymoma-associated myasthenia gravis, we briefly review myasthenia gravis associated with thymic lymphofollicular hyperplasia (TFH) and thymic atrophy.

Therapy in neuromuscular disease

The therapy of myasthenia gravis and inflammatory myopathy are discussed in detail in this article. The discussion of these two disorders illustrates the extraordinary progress that has been achieved in the therapy of neuromuscular disease.

Normal human immunoglobulin suppresses experimental myasthenia gravis in SCID mice

Serum IgM has been shown to participate in the control of IgG autoreactivity in healthy subjects. We have recently shown that an immunoglobulin preparation of pooled normal human IgM (IVIgM) contains anti-idiotypic antibodies against disease-associated IgG autoantibodies in autoimmune patients and protects rats from experimental autoimmunity. The aim of the present study was to asses the in vitro and in vivo immunomodulatory effects of IVIgM in comparison with IgG, in SCID mice reconstituted with thymic cells from a myasthenia gravis patient. Non-leaky SCID mice were injected i.p. with 60 x 10(6) thymic cells from a patient with myasthenia gravis and 1 day later boosted with 10(6) irradiated acetylcholine receptor (AchR)-expressing TE671 cells. On days 14, 21 and 28, mice were treated with IVIgM or with equimolar amounts of human serum albumin. The level of anti-AchR antibodies in the sera of three out of four IgM-treated animals was less than 1 nM. Further, there was a significant decrease in the loss of endplate AchR on the diaphragms of IgM-treated SCID mice. These findings indicate that pooled normal IgM exerts an immunoregulatory role in experimental myasthenia gravis, and suggests that IgM may be considered as an alternative approach in the therapy of autommune diseases.

The use of SCID mice in biotechnology and as a model for human disease

The use of SCID (severe combined immunodeficient) mice in medical research and biotechnology has increased tremendously in recent years. This review outlines the major characteristics of these animals and the impediments that they pose to the engraftment of human cells and tissues. The development of our SCID mice pretreatment protocol (anti-asialo GM1 antisera and radiation) is described, and the results of xenotransplantation studies of human cells and tissues in these pretreated animals are outlined. Wherever possible, data from transplantation studies (of human tissues and cells) in pretreated and nonpretreated animals are compared. The potential of our pretreated SCID mice for medical research and biotechnology is discussed.