Independent Effects of Interleukin‐6 (IL‐6) and Interleukin‐1 (IL‐1) on Accumulation of Specific mRNA for Fibrinogen and for Serum Amyloid A in Human Hepatoma (HepG2) Cellsa

HepG2 cells grown to confluence in modified F12 medium with 5% fetal calf serum exhibit constitutive expression of specific mRNA both for the gamma chain of fibrinogen ' (fibr) and for serum amyloid A (SAA; PA,,)' as determined by Northern blot analysis (FIGURES 1 and 2).The latter message ( -0.7 kb), previously undescribed in this cell line, is present despite the reported absence of secreted SAA in HepG2 spent m e d i ~m .~ Expression of both mRNAs persists in cells incubated in serum-free (1% BSA) medium.Purified human leukocyte interleukin-6 ( IL-6)4 induces a dosage-dependent enhanced accumulation of fibr mRNA (FIGURES 1 and 2).Human interleukin-lp, purified4 or recombinant, strongly reduces the basal accumulation of this message.The two agonists together produce an intermediate response.In contrast, SAA mRNA remains constant or is somewhat decreased by IL-6, and is increased modestly by IL-