The production of anti-IgG2a autoantibody in the 129/Sv mouse: onset in the lymph nodes draining the intestinal tract and prevention by neonatal thymectomy.

The histological distribution of anti-IgG-secreting cells was studied by measuring the amount of anti-IgG autoantibodies produced in vitro by cells isolated from various lymphoid organs. Before 20 wk, the production of anti-IgG autoantibody in 129/Sv mice from our Institute predominated in the mesenteric and caudal lymph nodes, which both drain the intestinal tract. After 20 wk, the production extended to the spleen and bone marrow. At that time no production was detected in the mediastinal, lumbar, and inguinal lymph nodes. A similar distribution of anti-IgG-secreting cells was observed in 25-wk-old 129/J mice from the Jackson Laboratory. These data indicate that anti-IgG autoimmunity in the 129 primarily results from a local immune response, probably induced by a specific stimulus of intestinal origin. Neonatal thymectomy prevented the production of anti-IgG, demonstrating that the mesenteric anti-IgG production did not result from the direct stimulation of B lymphocytes by endotoxin-like polyclonal activators. It was found that the anti-IgG produced in vitro had the same narrow specificity against IgG2a as its serum counterpart, indicating that this specificity resulted from the selective stimulation of anti-IgG2a-secreting cells rather than from in vivo consumption of anti-IgG antibodies recognizing other IgG subclasses.