[Modulation of experimental myasthenia gravis by IVIg]

Myasthenia Gravis (MG) is an autoimmune disease mediated by antibodies directed against the acetylcholine receptor (AChR). Treatment by IVIg is effective in acute forms of myasthenia gravis. In order to determine the in vivo effects of the various fractions of human immunoglobulins, we used an experimental model of myasthenia gravis in SCID mice. To this end, thymic cells from MG patients are transferred to these mice according to a well defined protocol. When establishing of the model, we noticed the appearance of anti-AChR antibodies and the loss of AChR expression at the muscle level. After treatment with IVIgG or IVIgM, the mice displayed a lower anti-AChR antibody titer compared to control mice (albumin treated) and the loss of the AChR number at the muscle was significantly reduced. These results obtained from one MG patient indicate that the human immunoglobulin preparations induce significant effects on pathogenic parameters in the SCID mouse model. Therefore this model is interesting to approach the mechanisms of action of human immunoglobulins and deserves further investigation.