A macrophage surface component related to fibronectin is involved in the response to migration inhibitory factor

Abstract

Guinea pig peritoneal exudate cells release a substance upon incubation with hypotonie buffer or 6 M urea which (1) augments the response of normal macrophages to migration inhibitory factor, and (2) restores the response of trypsinized macrophages to migration inhibitory factor. Adsorption of peritoneal exudate cell extract with antibodies to guinea pig plasma fibronectin results in a loss of both the MIF-response-enhancing and restoring activity. These results indicate that both activities are associated with a macrophage surface component serologically related to plasma fibronectin. Furthermore, preincubation of macrophages with plasma fibronectin abrogates the enhancement of the MIF response caused by peritoneal exudate cell extracts. This suggests that the active component and plasma fibronectin compete for a common binding site. It is likely that this substance plays a regulatory role in the macrophage response to migration inhibitory factor.