Studies on hepatic hemopoiesis induced by immunization with syngeneic liver extracts in mice.

After a 9-week immunization period, all the livers in inbred C57BL 6 mice immunized with syngeneic crude liver protein (LSN) in Freund's complete adjuvant showed histological changes mainly in the portal areas. Morphological features and the subsequent in vitro and in vivo data suggested that the principal histological changes were due to extramedullary hemopoiesis and not to autoimmune hepatitis. This is the first description of extramedullary hemopoiesis in studies concerning experimental autoimmune hepatitis. The significance of our findings is, first, that the occurrence of hepatic hemopoiesis induced by the usual immunization method necessitates morphologically distinct evidence of inflammation to be a prerequisite in studies of experimental autoimmune hepatitis. Without this proof, subsequent investigations would be confusing. Second, immunization can be added to a variety of conditions to induce hepatic hemopoiesis. This would provide a convenient and interesting tool for application to further studies of hemopoiesis.