The IgG subclass distribution of thyroglobulin antibody synthesized in culture.

Thyroglobulin autoantibodies synthesized by Hashimoto lymphocytes in culture and present in serum have been analysed in terms of their IgG subclass distribution. The autoantibodies produced in vitro were frequently IgG4 or IgG1, whether pokeweed mitogen or Epstein-Barr virus was used to stimulate the cultures, and the subclass distribution of these thyroglobulin antibodies was similar to that observed in the patients' serum. It appears therefore that the antibodies synthesized in vitro in response to polyclonal B-cell activators resemble those produced in vivo, and it seems likely that both pokeweed mitogen and Epstein-Barr virus influence the same B-cell precursors of autoantibody-synthesizing cells, albeit by different mechanisms.