Engraftment of myasthenia gravis thymocytes into severe combined immunodeficiency (SCID) mice

To study the human immune system, thymocytes from myasthenia gravis (MG) patients were transferred into the peritoneal cavity of severe combined immunodeficiency (SCID) mice, which caused the mice to produce human IgG and IgM. The injected thymocytes were then recovered from the peritoneal cavities of MG-SCID mice. The recovered thymocytes were CD3+ or CD20+ human cells expressing the MHC class II molecule. AChR-specific T cell lines were also recovered from peritoneal cells of the mice. These cells were made up of helper T (CD3+ CD4+ CD8- CD20- HLA-DR+), suppressor T (CD3+ CD4- CD8+ CD20- HLA-DR+), and probably NK cells (CD3- CD4- CD8- CD20- HLA-DR+). Therefore, the functional human T and B cells survived in the SCID mice for a long period. SCID mice may provide a unique tool in the study of human cell immunity by creating more congenial physiological conditions than conventional culture systems, and by providing an animal model of the human immune system.