Induction of rat α2‐macroglobulin in vivo and in hepatocyte primary cultures: synergistic action of glucocorticoids and a Kupffer cell‐derived factor

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Abstract
Turpentine injection into rats elicits enhanced secretion of acute phase proteins inducing α2-macroglobulin (α2M). Hypophysectomized rats, however, do not respond in this way unless dexamethasone is given together with turpentine. On the other hand, dexamethasone injection alone did not result in an induction of α2M synthesis. When a medium of Kupffer cell cultures was added to hepatocytes, a dose-dependent stimulation of α2M synthesis of up to 4-fold after 10–12 h was observed. However, the presence of low concentrations (10−9 M) of dexamethasone was essential for the stimulatory effect. We conclude that the acute phase induction of α2M in hepatocytes requires the synergistic action of glucocorticoids and a non-dialysable factor secreted by Kupffer cells.