Cell surface fibronectin of mouse peritoneal macrophages

Abstract

Fibronectin (FN) was detected on thioglycollate-induced mouse peritoneal macrophages by binding the 125I-labeled F(ab′) 2 fragment of rabbit anti-human plasma fibronectin. The cell surface fibronectin (sFN) was removed from the surface of the macrophage monolayer by limited trypsinization. After trypsinization, binding of 125I-labeled plasma fibronectin ( 125I-pFN) to the macrophage monolayer was increased, suggesting that the FN receptor covered with sFN was exposed by trypsinization without destroying the receptor activity. The amounts of saturation binding of 125I-pFN to the macrophage monolayers before and after trypsinization were about 2.4 and 6.3 μg per 10 6 cells, respectively, indicating that the macrophage monolayer has the capacity of binding 6.3 μg FN per 10 6 cells, and the FN receptor equivalent to about 4 μg pFN per 10 6 cells is covered with sFN.