Defective B cell memory and autoantibodies in subjects of cardiac transplantation in infancy (169.27)

Abstract

Abstract Aberrant functions of T cells and B cells may impair B cell memory and are thought to allow development of autoantibodies. Rarely, B cell memory defects and/or autoimmunity can be traced to specific mutations; however, in most cases which properties of T cells and B cells cause deficient B cell responses and/or autoimmunity are unclear. To answer these questions we studied child recipients of cardiac transplantation during infancy who, owing to removal of the thymus and T cell depletion at the time of surgery, have a greatly reduced T cell receptor repertoire diversity. We found these children to have impaired memory IgG antibody responses to polypeptide vaccines compared to controls, even though they appeared to mount IgM responses. These results suggest that the defective T cell compartment in recipients of cardiac transplantation in infancy impairs B cell memory and/or isotype class- switching. Remarkably, despite these defects and despite ongoing treatment with immunosuppressive drugs, 6 of the 9 subjects studied produced anti-ssDNA and rheumatoid factor antibodies as early as of 2 years of age. These findings suggest that the diversity of T cells and/or the availability of recent thymic emigrants are needed to generate B cell memory and prevent autoimmunity.