Lymphocytotoxins and immunologic unresponsiveness

A 14-year-old boy with a lifelong history of recurrnet infections and debilitating bronchiectasis was found to lack any evidence of humoral or cellular immunity. His serum contained a high titer of IgM antibody to the heavy chain of IgG and this antibody was also cytotoxic for peripheral lymphocytes. Complement-dependent lymphocytotoxicity could be blocked by IgG or Fc fragment. In this patient, immunosuppression may have been due to an autoantibody against both autologous IgG and lymphocyte plasma membrane.