Cultured hepatocytes from mouse strains expressing high and low levels of the fourth component of complement differ in rate of synthesis of the protein.

Primary hepatocyte cultures prepared from the livers of inbred strains of mice show different rates of synthesis for the fourth component of complement (C4). The relative amounts of C4 synthesized by hepatocyte cultures correspond to the relative plasma levels of C4 among strains, a trait determined by the S region of the H-2 major histocompatibility complex. There is no evidence for increased intracellular catabolism of C4 in hepatocyte cultures from a strain with a low level of plasma C4. Processing and secretion of C4 proceed very slowly in vitro relative to other hepatocyte proteins.