beta 2-microglobulin (beta 2-M) was secreted in a dose- and time-dependent manner after interleukin-6 (IL-6) treatment of human hepatoblastoma (HuH-6) and hepatoma cells (HuH-7). Pancreatic secretory trypsin inhibitor, which is one of the acute phase proteins secreted in these cells, was also secreted dose- and time-dependently in HuH-6 cells and dose-dependently in HuH-7 cells. It is conceivable that IL-6 induces the production of beta 2-M as an acute phase protein in the liver.