TRANSCRIPTIONAL ACTIVATION OF THE FACTOR-VIII GENE IN LIVER-CELL LINES BY INTERLEUKIN-6

Circulating factor VIII (fVIII) levels increase during inflammation su ggesting that fVIII synthesis or secretion is stimulated during acute inflammation. To examine the mechanisms underlying this increase in ci rculating factor VIII, we have developed a sensitive and reliable semi quantitative assay for fVIII mRNA utilising competitive reverse transc riptase-polymerase chain reaction (RT-PCR, and used this to study two human liver cell lines, Hep-G2 and Chang Liver cells. These cells were cultured under basal conditions or following treatment with interleuk in-1, -2 and 6 (IL-1, -2, and -6). Following 18h culture with IL-6 (ma ximum concentration 40U/ml), these levels had risen 6 and 9 fold respe ctively, with no concomitant rise in control RNA levels. The dose resp onses for both cell types were similar, with an ED50 of 11 U/ml. The t ime course of this response was also similar in both cell lines with t he increase in Nm mRNA first reaching significance by 3 h, and reachin g maximum levels by 12 h. IL-1 and IL-2 had no effect at any of the do ses studied. This study provides the first evidence for regulated expr ession of fVIII in human cell lines, and suggests that increased plasm a Nm levels during the acute phase response may be due to increased ex pression of fVLII mRNA.